TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
A1 - Meyer, Andreas
T1 - Poly(butylene terephthalate): About condensation, cyclization, degradation and elimination reactions in the solid state, and the role of smooth crystal surfaces
N2 - Three commercial poly(butylene terephthalate) (PBT) samples - Pocan B1300 (B13), Pocan B1600 (B16), and Addigy P 1210 (AP121) - served as the starting materials for the annealing experiments, which were conducted with and without the addition of esterification and transesterification catalysts. The catalysts used were Sn(II) 2-ethylhexanoate (SnOct₂), Zr(IV) acetylacetonate, and 4-toluene sulfonic acid (TSA). Temperatures varied between 150 and 210 °C. The PBT samples were characterized using differential scanning calorimetry (DSC), gel permeation chromatography (GPC), small-angle X-ray scattering (SAXS), and matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry. The MALDI mass spectra of all three samples differed greatly but displayed mass peaks of cycles. Similar results were produced by annealing with SnOct₂ or Zr(acac)₄, which favored the formation of even-numbered cycles within the mass range below m/z 5000, along with slow degradation. TSA favored a more intensive degradation without the formation of cycles or even with the destruction of cycles. PBT chains with two carboxylic (COOH) end groups were the most stable species under all circumstances. The origin of the extremely high melting point of AP121 (241–242 °C) can be explained by the smoothing of crystallite surfaces via transesterification. The results suggest that combining MALDI mass spectrometry and SAXS measurements provides a new way to better understand the solid-state chemistry of PBT and related polyesters.
KW - MALDI-TOF MS
KW - Polybutylene Terephthalate
KW - Crystallization
KW - solid state
KW - cyclization
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652844
DO - https://doi.org/10.1016/j.polymdegradstab.2025.111862
SN - 0141-3910
VL - 245
SP - 1
EP - 11
PB - Elsevier Ltd.
AN - OPUS4-65284
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dalgic, Mete‐Sungur
A1 - Kumar, Sourabh
A1 - Weidner, Steffen
T1 - Quantitative Analysis of Polymers by MALDI‐TOF Mass Spectrometry: Correlation Between Signal Intensity and Arm Number
N2 - The signal intensities of linear and star‐shaped poly(L‐lactides) (PLA) and poly (ethylene oxides) (PEO) were compared to determine the influence of the number of arms on the ionization in matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry. In this study, a variety of blends were prepared and investigated, including binary and ternary combinations of linear and star‐shaped polymers with similar molecular masses. The focus was on examining their intensity ratios. In equimolar binary PLA blends, polymer stars were observed to exhibit higher intensities than their linear counterparts. This result was supported by experiments with equimolar ternary PLA blends, which clearly demonstrated an intensity dependence on the number of polymer arms. It was observed that four‐arm PLA exhibited higher intensities than three‐arm PLA. A similar trend was observed in investigations involving acetylated polymer end groups, suggesting that differences in ionization are primarily influenced by polymer architecture rather than end groups. In order to validate this assumption, the binding energies for [polymer‐K] + adduct ions utilizing the most stable geometry obtained from GOAT (Global Optimizer Algorithm) were calculated, revealing that star‐shaped lower mass oligomers have slightly higher binding energies.
KW - MALDI-TOF MS
KW - Starlike polymers
KW - Quantification
KW - Topology
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653401
DO - https://doi.org/10.1002/jms.70023
SN - 1076-5174
VL - 61
IS - 1
SP - 1
EP - 12
PB - John Wiley & Sons Ltd.
AN - OPUS4-65340
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, Andreas
A1 - Falkenhagen, Jana
A1 - Kricheldorf, Hans R.
T1 - Cyclic polyglycolide by means of metal acetylacetonates
N2 - Glycolide was polymerized in bulk at 160 °C using various metal acetylacetonates as catalysts. Zirconium acetylacetonate was particularly efficient, enabling rapid polymerization even at 130 °C. The formation of cyclic poly(glycolic acid) (PGA), most likely via a ring-expansion polymerization (REP) mechanism, was proven by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Depending on the polymerization conditions, the formation of even-numbered cycles was favored to varying degrees. Number-average molecular weights (Mn) in the range of 2000–3500 g mol−1 were achieved with dispersities below 2.0. Wide-angle X-ray scattering (WAXS) powder patterns showed that the crystal lattice was the same as that of known linear PGAs, regardless of the Mn values. These patterns enabled a comparison of crystallinities with values derived from DSC measurements.
KW - MALDI-TOF MS
KW - Polyglycolide
KW - Crystallization
KW - Small-angle X-ray scattering
KW - Cyclization
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653731
DO - https://doi.org/10.1039/d5ra07961f
SN - 2046-2069
VL - 16
IS - 2
SP - 1757
EP - 1764
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-65373
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Jlalia, I.
A1 - Gomri, M.
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Weidner, Steffen
A1 - Abderrazak, H.
A1 - Marestin, C.
A1 - Mercier, R.
A1 - Ben Halima, H.
A1 - Lakard, B.
A1 - Jaffrezic Renault, N.
T1 - Design of Fluorinated Poly(Ether-Pyridine) Films for Impedimetric Detection of Heavy Metal Ions
N2 - A series of fluorinated poly(ether-pyridine)s were synthesized via polycondensation of bis-perfluoropyridine with either bisphe-nol A (BPA) or isosorbide, a bio-sourced diol. The polymers were characterized using 1 H and 19 F NMR spectroscopy, and their molecular weights were determined using GPC. Thermal properties were assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The presence of isosorbide in polymer P2 increases the glass transition temperature and results in a lower molecular weight and a higher hydrophilicity. On the other hand, polymer P3, based on BPA, shows the best thermal stability, the highest molecular weight, and the most pronounced hydrophobic character. Electrochemical impedance spectroscopy (EIS) was used to evaluate the modified gold electrodes for the selective detection of metal ions. Among the four target ions (Ni 2+, Cd 2+, Pb2+, and Hg 2+), defined by the European Water Framework Directive, Pb2+ was selectively detected on the hydrophilic polymer P2, while Cd 2+ was selectively detected on the hydrophobic polymer P3. The achieved detection limits were 5 × 10−11 M, corresponding to 10 ng/L for Pb2+ and 5.6 ng/L for Cd 2+, respectively.
KW - Cadmium
KW - Electrochemical impedance spectroscopy
KW - Fluorinated polyether pyridines
KW - Isosorbide
KW - Lead
PY - 2025
DO - https://doi.org/10.1002/pat.70038
SN - 1099-1581
VL - 36
IS - 1
SP - 1
EP - 14
PB - John Wiley & Sons Ltd.
AN - OPUS4-62384
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans. R.
A1 - Weidner, Steffen
T1 - About the Toxicity of Polymerization Catalysts and Polymer Additives Based on Tin(II) Salts and Tin(IV) Compounds
N2 - This article reviews and discusses information on the toxicity of numerous tin-based catalysts used in academic research and industrial production for the synthesis of various polymers, such as polyesters, polyurethanes, and polysiloxanes. Tin(IV) compounds used as additives and as PVC stabilizers are also considered. Emphasis is put on the differentiation between tin(II) salts on the one hand and tin(IV) compounds on the other hand. In the first chapter, historical facts about human contact with stannous ions are discussed, along with toxicity studies of canned foods and beverages. In the second part, toxicity tests based on cell cultures and medical applications of tin(II)-containing films or implants are described. The third part focuses on alkyl and aryl tin(IV) compounds.
KW - Tin
KW - Toxicity
KW - Environment
KW - Polymer catalysts
KW - Polymer additives
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642877
DO - https://doi.org/10.1021/acs.chas.5c00105
SN - 1871-5532
SP - 1
EP - 13
PB - American Chemical Society (ACS)
AN - OPUS4-64287
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Meyer, Andreas
A1 - Weidner, Steffen
A1 - Kricheldorf, Hans R.
T1 - Star-shaped poly(l-lactide)s based on pentaerythritol: About crystallization and polycondensation plus disproportionation and ring formation in the solid state
N2 - Star-shaped poly( L-lactide)s (s-PLAs), were prepared by ring-opening polymerization of with pentaerythritol and catalyzed by tin(II) 2-ethylhyexanoate (SnOct out in bulk at either 120 ◦ C or 160 ◦ L-lactide (LA) initiated 2 ). Two small series of ROPs were carried C with variation of the LA/initiator ratio. Matrix-assisted laser desorption/ ionization time-of-flight (MALDI-TOF) mass spectra revealed traces of cycles in 120 ◦ C samples only at low initiator/catalyst ratios. In contrast, higher fractions of cycles were detected in samples prepared at 160 C, suggesting a "back-biting" origin. The influence of arm length and thermal history on crystallinity was investigated by differential scanning calorimetry (DSC) and wide-angle x-ray scattering (WAXS). It was shown that annealing increased the melting temperature (T ◦ ◦ m ) and crystallinity. However, annealing at 140 ◦ C for 14 d also caused significant solid-state transesterification. In addition, crystallites composed of s-PLAs with extended arms and, simultaneously, crystallites composed exclusively of extended rings were formed, identified by their typical "sawtooth" pattern in the MALDI mass spectra. Small angle x-ray scattering (SAXS) indicated that the crystal thickness was lower than that of linear PLAs annealed under identical conditions, but increased upon annealing at 140 C.
KW - MALDI-TOF MS
KW - Polylactide
KW - Crystallisation
KW - AStar-shaped polymers
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636832
DO - https://doi.org/10.1016/j.polymer.2025.128709
SN - 0032-3861
VL - 334
SP - 1
EP - 11
PB - Elsevier Ltd.
AN - OPUS4-63683
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - H2O-Initiated Polymerization of L-Lactide
N2 - Water-initiated ring-opening polymerizations (ROPs) of L-lactide (LA) were performed in bulk at 140 °C, whereupon 11 different salts or complexes of low-toxic metal ions such as tin (II), Zn(II), Zr(IV), and Bi(III) were used as catalysts. Only four catalysts gave satisfactory results despite a long reaction time (24 h). The influence of the temperature was studied with tin (II) 2-ethylhexanoate (SnOct2), dibutyltin oxide (Bu2SnO), and zinc bis-acetylacetonate (Zn(acac)2) and zirconium acetylacetonate (Zr(acac)4). With SnOct2, Bu2SnO and Zr(acac)4 the time was varied at 140 °C to compare their reactivity. Furthermore, two series of ROPs were carried out with variation of the LA/H2O ratio to verify the control of the molecular weight by the monomer-initiator ratio. Bi- or tri-modal molecular weight distributions (MWD) were found for most of the ROPs and bimodal melting endotherms in the differential scanning calorimetry (DSC) heating traces. The thickness and dependence of the 3D packing of the crystallites were monitored by small-angle X-ray scattering (SAXS) measurements.
KW - MALDI-TOF MS
KW - Polylactide
KW - Ring-opening polymerization
KW - Crystallization
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628761
DO - https://doi.org/10.1007/s10924-025-03565-w
SN - 1572-8919
VL - 33
IS - 6
SP - 2843
EP - 2857
PB - Springer Science and Business Media LLC
CY - New York, NY
AN - OPUS4-62876
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
A1 - Scheliga, Felix
T1 - Polycondensation of L-lactic acid: a deeper look into solid state polycondensation
N2 - L-Lactic acid (LA) was condensed in the presence of SnCl2 or 4-toluenesulfonic acid (TSA) at 140 °C, and chain growth without cyclization was observed. In addition, poly(L-lactic acid)s (PLAs) with a degree of polymerization (DP) of 25, 50 or 100 were prepared by water-initiated ring-opening polymerization (ROP). These PLAs were annealed in the solid state at 140 °C and 160 °C in the presence of tin(II) 2-ethylhexanoate (SnOct2, SnCl2 or TSA). The changes in the molar mass distribution and in the topology were characterized by means of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and size exclusion chromatography (SEC). With increasing time, fewer side reactions caused higher molar masses and increasing fractions of cyclic polylactides (cPLA) were obtained. Their “saw tooth” pattern in the MALDI-TOF mass spectra indicated the formation of extended ring crystallites in the solid state. TSA was the most active catalyst and caused fewer side reactions than SnCl2, which was the least reactive catalyst. Acetylation of the CH-OH end groups hindered polycondensation and prevented the formation of cPLAs. Reaction mechanisms will be discussed.
KW - MALDI-TOF MS
KW - Polycondensation
KW - Polylaktide
KW - Solid state
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625271
DO - https://doi.org/10.1039/d4py01191k
SN - 1759-9962
SP - 1
EP - 9
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-62527
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rösler, Alexander
A1 - Weidner, Steffen
A1 - Klamroth, Tillmann
A1 - Müller, Axel HE
A1 - Schlaad, Helmut
T1 - Kinetics of anionic polymerization of β‐myrcene in hydrocarbon solvents
N2 - AbstractThe kinetics of anionic polymerization of β‐myrcene initiated by sec‐butyllithium were examined in saturated and unsaturated hydrocarbon solvents, i.e. cyclohexane, cyclohexene, 4‐vinylcyclohexene and dl‐limonene. Polymerizations usually proceeded in a living manner, i.e. in the absence of termination and chain transfer reactions, in all solvents, to produce well‐defined polymyrcenes with high content (85%) of cis‐1,4 units. However, polymyrcenyllithium chains exhibited limited long‐term stability in 4‐vinylcyclohexene solution, most probably due to chain transfer to solvent. Reaction orders with respect to the concentration of active chains were found to be one‐quarter in cyclohexane increasing to one‐half in unsaturated solvents, indicating that the polymyrcenyllithium chains are present as tetrameric or dimeric associates, respectively. Apparent activation energies were found to be 81 kJ mol−1 in cyclohexane and 77 kJ mol−1 in dl‐limonene solution, which are close to the values obtained by quantum chemical calculations. © 2025 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
KW - Myrcene
KW - Anionic polymerization
KW - Reaction order
KW - Activation energy
KW - Microstructure
KW - Quantum chemical calculation
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636840
DO - https://doi.org/10.1002/pi.6772
SN - 0959-8103
SP - 1
EP - 8
PB - Wiley
AN - OPUS4-63684
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
T1 - Syntheses of cyclic polylactides and the problem of catenane formation
N2 - Cyclic poly(L-lactide)s (PLAs) were prepared in bulk either by ring-expansion polymerization (REP) or by ring-opening polymerization (ROP) with simultaneous polycondensation (ROPPOC). In contrast to REP the latter method involves formation of linear chains and thus, may involve formation of polydisperse catenanes that affect crystallization. The reprecipitated PLAs were annealed at 120 °C and compared with regard to melting temperature (Tm) and melting enthalpy (ΔHm). For similar molar masses the PLAs prepared by REP and ROPPOC had almost identical Tm's and crystallinities. Furthermore, the influence of REP and ROPPOC catalysts on the morphology of the virgin reaction products was compared.
KW - MALDI-TOF MS
KW - Catenane
KW - Polylactide
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625061
DO - https://doi.org/10.1039/d4ra08683j
VL - 15
IS - 5
SP - 3686
EP - 3692
PB - RSC
AN - OPUS4-62506
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rösler, Alexander
A1 - Weidner, Steffen
A1 - Klamroth, Tillmann
A1 - Müller, Axel H. E.
A1 - Schlaad, Helmut
T1 - Kinetics of anionic polymerization of β‐myrcene in hydrocarbon solvents
N2 - The kinetics of anionic polymerization of β‐myrcene initiated by sec‐butyllithium were examined in saturated and unsaturated hydrocarbon solvents, i.e. cyclohexane, cyclohexene, 4‐vinylcyclohexene and dl‐limonene. Polymerizations usually proceeded in a living manner, i.e. in the absence of termination and chain transfer reactions, in all solvents, to produce well‐defined polymyrcenes with high content (85%) of cis‐1,4 units. However, polymyrcenyllithium chains exhibited limited long‐term stability in 4‐vinylcyclohexene solution, most probably due to chain transfer to solvent. Reaction orders with respect to the concentration of active chains were found to be one‐quarter in cyclohexane increasing to one‐half in unsaturated solvents, indicating that the polymyrcenyllithium chains are present as tetrameric or dimeric associates, respectively. Apparent activation energies were found to be 81 kJ mol−1 in cyclohexane and 77 kJ mol−1 in dl‐limonene solution, which are close to the values obtained by quantum chemical calculations.
KW - MALDI-TOF MS
KW - Anionic polymerization
KW - β‐myrcene
KW - Kinetics
KW - Reaction order
KW - Activation energy
KW - Microstructure
KW - Quantum chemical calculations
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630900
DO - https://doi.org/10.1002/pi.6772
SN - 1097-0126
SP - 1
EP - 8
PB - Wiley
CY - New York, NY
AN - OPUS4-63090
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - Zwitterionic polymerization of glycolide catalyzed by pyridine
N2 - The usefulness of various N- and P-based catalysts for syntheses of cyclic polyglycolide via zwitterionic polymerization of glycolide was examined. Most catalysts produced discolored, largely insoluble polyglycolides consisting of cycles and unidentified byproducts. Soluble, cyclic polyglycolides were obtained using neat pyridine as catalyst at 120 °C, 100 °C, 80 °C, and even at 60 °C. The number-average molecular weights were extremely low and depended slightly on the glycolide-to-pyridine ratio. Three different mass distributions of the cycles were detected by mass spectrometry, depending on the reaction conditions. The cyclic polyglycolides were also characterized by differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) measurements. The SAXS data in combination with the mass spectra indicate that the majority of the cycles form extended-ring crystallites
KW - MALDI-TOF MS
KW - Polylactide
KW - Polymerization
KW - Zitterions
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639748
DO - https://doi.org/10.1039/d5py00762c
SN - 1759-9954
SP - 1
EP - 9
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-63974
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rösler, Alexander
A1 - Weidner, Steffen
A1 - Klamroth, Tillmann
A1 - Müller, Axel HE
A1 - Schlaad, Helmut
T1 - Kinetics of anionic polymerization of β‐myrcene in hydrocarbon solvents
N2 - AbstractThe kinetics of anionic polymerization of β‐myrcene initiated by sec‐butyllithium were examined in saturated and unsaturated hydrocarbon solvents, i.e. cyclohexane, cyclohexene, 4‐vinylcyclohexene and dl‐limonene. Polymerizations usually proceeded in a living manner, i.e. in the absence of termination and chain transfer reactions, in all solvents, to produce well‐defined polymyrcenes with high content (85%) of cis‐1,4 units. However, polymyrcenyllithium chains exhibited limited long‐term stability in 4‐vinylcyclohexene solution, most probably due to chain transfer to solvent. Reaction orders with respect to the concentration of active chains were found to be one‐quarter in cyclohexane increasing to one‐half in unsaturated solvents, indicating that the polymyrcenyllithium chains are present as tetrameric or dimeric associates, respectively. Apparent activation energies were found to be 81 kJ mol−1 in cyclohexane and 77 kJ mol−1 in dl‐limonene solution, which are close to the values obtained by quantum chemical calculations. © 2025 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
KW - Myrcene
KW - Anionic polymerization
KW - MALDI TOF MS
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-649039
DO - https://doi.org/10.1002/pi.6772
SN - 0959-8103
SP - 1
EP - 8
PB - Wiley
AN - OPUS4-64903
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - Polymerization of L‐Lactide Catalyzed by Metal Acetylacetonate Complexes
N2 - ABSTRACTRing‐opening polymerizations (ROPs) of l‐lactide (LA) were performed at 120°C, 140°C, 150°C, and 180°C in bulk catalyzed by acetylacetonate (acac) complexes of manganese(II), nickel(II), copper(II), zirconium(IV), dibutyltin(IV), and vanadyl(V). These experiments revealed that only the acac complexes of Zr and Bu2Sn were reactive enough to enable quantitative polymerization within a few hours. Further ROPs with Bu2Sn(acac)2 and Zr(acac)4 showed that Bu2Sn(acac)2 had a slightly lower reactivity than the Zr complex. The ROPs catalyzed with Zr(acac)4 yielded number average molecular weights (Mn) up to 70,000 g mol−1. The matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra indicated an exclusive formation of cycles in the mass range of up to m/z 13,000 for Zr(acac)4 and up to m/z 18,000 for Bu2Sn(acac)2. Unusually high melting temperatures (187°C–192°C) were also achieved along with high crystallinities. Furthermore, four lactide/glycolide copolymerizations catalyzed by Zr(acac)4 were performed, and the topology and the extent of transesterification were characterized by MALDI‐TOF mass spectrometry and 13C NMR spectroscopy.
KW - MALDI-TOF MS
KW - Polycondensation
KW - Acetylacetonate
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639754
DO - https://doi.org/10.1002/pol.20250788
SN - 2642-4150
SP - 1
EP - 9
PB - Wiley Periodicals LLC.
AN - OPUS4-63975
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Falkenhagen, Jana
A1 - Dalgic, Mete-Sungur
A1 - Weidner, Steffen
T1 - Quantitative MALDI-TOF Mass Spectrometry of Star-Shaped Polylactides Based on Chromatographic Hyphenation
N2 - The end groups of three- and four-arm star-shaped polylactides (PLA) with trimethylolpropane and pentaerythritol core structures were functionalized with acetic acid. Reaction products with different degrees of functionalization were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Additional gradient elution liquid adsorption chromatography (GELAC) measurements were performed to determine the degree of functionalization. This technique enabled clear separation and sufficient quantification of the formed species. These chromatographic data could be used inversely to quantify mass spectrometric results, which are usually biased by the unknown ionization probabilities of different polymer end group structures. Our results showed that, in this particular case, the peak intensity in the MALDITOF mass spectra can be used to semiquantitatively determine the degree of functionalization in incompletely functionalized multiarm PLA.
KW - Polylactides
KW - MALDI-TOF-MS
KW - Gradient elution liquid adsorption chromatography
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625292
DO - https://doi.org/10.1021/jasms.4c00491
SN - 1879-1123
SP - 1
EP - 9
PB - American Chemical Society (ACS)
AN - OPUS4-62529
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bui, Minh
A1 - Heinekamp, Christian
A1 - Fuhry, Emil
A1 - Weidner, Steffen
A1 - Radnik, Jörg
A1 - Ahrens, Mike
A1 - Scheurell, Kerstin
A1 - Balasubramanian, Kannan
A1 - Emmerling, Franziska
A1 - Braun, Thomas
T1 - Lewis-acid induced mechanochemical degradation of polyvinylidene fluoride: transformation into valuable products
N2 - Polyvinylidene fluoride (–[CH2CF2]n–, PVDF) waste poses significant environmental challenges due to its recalcitrant nature and widespread use. This study addresses the end-of-life management of PVDF by introducing a novel, sustainable mechanochemical approach for its valorisation. We investigated the degradation of PVDF into value-added materials using ball milling with anhydrous AlCl3 to achieve a quantitative mineralisation producing AlF3 and halide-functionalised graphite, along with gaseous products (HCl and CH4). Mechanistic key steps involve Lewis-acid catalysed C–F bond activation, dehydrofluorination and aromatisation. This approach provides an effective solution for PVDF waste management while offering a promising route for the production of high-value materials from polymer waste streams. Our findings contribute to sustainable practices in polymer recycling and resource recovery, respond to pressing environmental concerns associated with fluoropolymer disposal, and demonstrate the potential to convert polymer wastes into useful products.
KW - Mechanochemistry
KW - Polyvinylidenfluoride
KW - Degradation
KW - Ball mill
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-649015
DO - https://doi.org/10.1039/d5sc05783c
SN - 2041-6520
VL - 16
IS - 40
SP - 18903
EP - 18910
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64901
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Syntheses of high molecular mass polyglycolides via ring-opening polymerization with simultaneous polycondensation (ROPPOC) by means of tin and zinc catalysts
N2 - Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2-ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro-phenoxide) (BuSnOPF),zinc biscaproate (ZnCap), and zinc bis(pentafluoro-phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal-to-noise ration and displayed the peaks of cyclic PGAs with a“saw-tooth pattern ”indicating formation of extended-ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long-distance values measured by SAXS were small and varied little with the polymeriza-tion conditions.
KW - MALDI TOF MS
KW - Polyglycolide
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598221
DO - https://doi.org/10.1002/pat.6365
VL - 35
IS - 4
SP - 1
EP - 10
PB - John Wiley & Sons Ltd.
AN - OPUS4-59822
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
T1 - Low Molar Mass Cyclic Poly(L-lactide)s: Separate Transesterification Reactions of Cycles and Linear Chains in the Solid State
N2 - L-Lactide (LA) was polymerized with neat tin(II) 2-ethylhexanoate (SnOct2) in toluene at 115 °C at low concentration with variation of the LA/Cat ratio. Cyclic polylactides (cPLAs) with number average molecular weights (Mn) between 7 000 and 17 000 were obtained. MALDI-TOF mass spectrometry also revealed the formation of a few percent of linear chains. Crystalline cPLAs with Mn around 9 000 and 14 000 were annealed at 140 °C in the presence of ScOct2 or dibutyl-2-stanna-1,3-dithiolane (DSTL). Simultaneously, crystallites of extended linear chains and crystallites of extended cycles were formed regardless of the catalyst, indicating that transesterification reaction proceeded different for linear chains and for cycles, governed by thermodynamic control. The formation of extended chain crystallites with low dispersity indicates the existence of symproportionation of short and long chains. A complementary experiment was carried out with a PLA ethyl ester composed mainly of linear chains with a small fraction of cycles
KW - Polylactide
KW - MALDI-TOF MS
KW - Annealing
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606228
DO - https://doi.org/10.1039/D4SM00567H
SN - 1744-6848
SP - 1
EP - 12
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60622
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H.
T1 - Transformation of poly(L-lactide) crystals composed of linear chains into crystals composed of cycles
N2 - A poly(L-lactide) with a trifluoroethyl ester end group and an average degree of polymerization (DP) of 50 was synthesized by ROP of L-lactide initiated with trifluoroethanol. Small-angle X-ray scattering (SAXS) in combination with differential scanning calorimetry (DSC) measurements revealed an average crystal thickness of 13 nm, corresponding to 45 repeat units. This suggests that most crystallites were formed by extended PLA chains, and both flat surfaces were covered by CF3 groups. The crystalline PLAs were annealed at 140 or 160 °C in the presence of two catalysts: tin(II) 2-ethylhexanoate, (SnOct2) or dibutyltin bis(pentafluorophenoxide) (BuSnPhF). The chemical reactions, such as polycondensation and cyclization, proceeded in the solid state and were monitored by matrix-assisted laser desorption/ionization time-offlight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC) measurements. Under optimal conditions a large fraction of linear chains was transformed into crystallites composed of extended cycles. Additionally, MALDI TOF MS analysis of GPC fractions from samples annealed for 28 or 42 days detected chain elongation of the linear species up to a factor of 20.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
KW - Transesterification
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597250
DO - https://doi.org/10.1039/D3PY01370G
SN - 1759-9954
VL - 15
IS - 12
SP - 1173
EP - 1181
PB - Royal Society for Chemistry
AN - OPUS4-59725
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About alcohol-initiated polymerization of glycolide and separate crystallization of cyclic and linear polyglycolides
N2 - Alcohol-initiated polymerizations of glycolide (GL) catalyzed by tin(II) 2-ethylhexanoate (SnOct2) were carried out in bulk with variation of GA/In ratio, temperature and time. Due to a rather strong competition of cyclization polyglycolide (PGA) free of cycles were never obtained. When the cyclic catalysts 2,2-dibutal-2-stanna − 1,3-dithiolane (DSTL) or 2-stanna 1,3-dioxo-4,5,6,7 bibenzepane (SnBiph) were used in combination with 1,4-butanediol the influence of cyclization was even stronger. Furthermore, the degrees of polymerization were higher than the GA/alcohol ratio due to rapid polycondensation in the solid state. At 160 °C or below, the matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra indicated separate crystallization of low molar mass cyclic and linear PGAs from the same reaction mixture (also observed for poly(L-lactide)s).
KW - MALDI TOF MS
KW - Polyglycolide
KW - Ring opening polymerization
KW - Cyclization
KW - Crystallization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607282
DO - https://doi.org/10.1016/j.polymer.2024.127440
SN - 0032-3861
VL - 309
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-60728
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Syntheses of Polyglycolide via Polycondensation: A Reinvestigation
N2 - The Na salt of chloroacetic acid is condensed in suspension. Furthermore,glycolic acid is condensed in bulk or in concentrated solution by means of SnCl2 or 4-toluene sulfonic acid (TSA) as catalysts. The temperatures are varied from 160 to 200°C and the time from 1 to 5 days. Low molar mass cyclic poly(glycolic acid) (PGA) is detected by means of matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry in most PGAs. A predominance of certain cycles having an even number of repeat units is observed suggesting a thermodynamically favored formation of extended-ring crystals. Extremely high melting temperatures (up to 237.5°C)and high melting enthalpies are found for polycondensations with TSA in 1,2-dichlorobenzene.
KW - MALDI TOF MS
KW - Polycondensation
KW - Polyglycolide
KW - Cyclization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596856
DO - https://doi.org/10.1002/macp.202300397
IS - 2300397
SP - 1
EP - 7
PB - Wiley VHC-Verlag
AN - OPUS4-59685
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Scheliga, Felix
A1 - Kricheldorf, Hans R.
T1 - Polycondensation, Cyclization and Disproportionation of Solid Poly(L-lactide) Trifluoroethyl Esters and the Simultaneous Formation of Extended Chain Crystals and Extended Ring Crystals
N2 - Two poly(L-lactide)s (PLAs) with a degree of polymerization (DP) of 20 or 100 were prepared by trifluoroethanol-initiated ring-opening polymerization (ROP) catalyzed by tin(II) 2-ethyl hexanoate (SnOct2). These PLAs were annealed at 140 ◦C or at 160 ◦C in the presence of SnOct2, and the changes in topology and molecular weight distribution (MWD) were monitored by matrix-assisted laser desorption/ionization time-of flight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC). For the PLA with a DP 20, the main reaction was polycondensation combined with higher dispersities. In the case of the DP 100, PLA polycondensation was combined with disproportionation and the formation of a new MWD maximum around m/z 3500. In addition, extensive cyclization occurred, and the resulting cyclic PLAs crystallized separately from the linear chains in the form of extended ring crystals. These results also suggest that both extended chain and extended ring crystals posses the same crystal thickness as a result of thermodynamically controlled transesterification in the solid state.
KW - Polycondensation
KW - MALDI
KW - Polylactide
KW - Cyclization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616441
DO - https://doi.org/10.1016/j.polymer.2024.127800
VL - 315
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-61644
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H.
T1 - Cyclic polyglycolides via ring-expansion polymerization with cyclic tin catalysts
N2 - Glycolide was polymerized in bulk with two cyclic catalysts − 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzepane (SnBiph). The monomer/initiator ratio, temperature (140 – 180 °C) and time (1–––4 days) were varied. The MALDI TOF mass spectra exclusively displayed peaks of cyclic polyglycolide (PGA) and revealed an unusual “saw-tooth pattern” in the mass range below m/z 2 500 suggesting formation of extended ring crystallites. The DSC measurements indicated increasing crystallinity with higher temperature and longer time, and after annealing for 4 d at 160 °C a hitherto unknown and unexpected glass transition was found in the temperature range of 170–185 °C. Linear PGAs prepared by means of metal alkoxides under identical conditions did not show the afore-mentioned features of the cyclic PGAs, neither in the mass spectra nor in the DSC measurements. All PGAs were also characterized by SAXS measurements, which revealed relatively small L-values suggesting formation of thin crystallites in all cases with little influence of the reaction conditions.
KW - Polyglycolide
KW - MALDI-TOF MS
KW - Ring-expansion polymerization
KW - Crystals
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595541
DO - https://doi.org/10.1016/j.eurpolymj.2024.112811
SN - 0014-3057
VL - 207
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-59554
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About Polycondensation, Disproportionation, and Cyclization of Acetylated Poly(L-Lactide) Esters
N2 - L-lactide (LA) is polymerized with ethyl L-lactate or trifluoroethanol as initiators (LA/In = 30/1), and the resulting poly(L-lactide) esters are acetylated with acetic anhydride. The acetylated PLA esters are mixed with SnOct2, dibutyltin bis(4-chlorophenoxide), or dibutyltin bis(pentafluorophenoxide) in solution and crystallized at 120 °C. The doped crystals are annealed at 140 °C or at 160 °C for 7, 14, and 28 days, and the chemical modifications that occurred in the solid state are monitored by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) measurements. All catalysts promoted polycondensation, while no significant formation of cycles is observed. However, in the presence of SnOct2, disproportionation of chains occurred upon annealing at 120 or 140 °C, and crystallites consisting of extended chains with Mn values ≈3500 – 3600 and low dispersities (Ð < 1.5) are formed.
KW - MALDI-TOF MS
KW - Polycondensation
KW - Polylactides
KW - Transesterifcation
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630349
DO - https://doi.org/10.1002/macp.202400175
SN - 1521-3935
VL - 225
IS - 19
PB - Wiley VHC-Verlag
AN - OPUS4-63034
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Scheliga, F.
T1 - Polycondensation of poly(L-lactide) alkyl esters combined with disproportionation and symproportionation of the chain lengths
N2 - Ring-opening polymerizations (ROPs) of l-lactide (LA) were performed with ethyl l-lactate or 11-bromoundecanol as initiators (In) and tin(II) ethyl hexanoate (SnOct2) as catalyst (Cat) using four different LA/In ratios (20/1, 40/1, 60/1, and 100/1). One series of ROPs was conducted in bulk at 120 °C, yielding PLAs with low dispersities (Ð ~ 1.2–1.4), and a second series was conducted in bulk at 160 °C, yielding higher dispersities (Ð ~ 1.3–1.9). Samples from both series were annealed for 1 or 14 days at 140 °C in the presence of SnOct2. Both polycondensation and disproportionation reactions occurred, so that all four samples tended to form the same type of molar mass distribution below 10,000 Da, regardless of their initially different number average molar masses (Mn). Both initiators gave nearly identical results. The thermodynamic control of all reversible transesterification processes favored the formation of crystallites composed of chains with a Mn around 3500–3700, corresponding to a crystal thickness of 10–13 nm.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600081
DO - https://doi.org/10.1002/pol.20240118
SN - 2642-4150
SP - 1
EP - 12
PB - Wiley
AN - OPUS4-60008
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Cherbib, S.
A1 - Jlalia, I.
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Marestin, C.
A1 - Mercier, R.
A1 - Weidner, Steffen
A1 - Casabianca, H.
A1 - Jaffrezic-Renault, N.
A1 - Abderrazak, H.
T1 - Design of New Partially Bio-Based Polyguanamines for the Reversible Adsorption of Phenolic Molecules from Olive Mill Wastes
N2 - Olive mill wastewater produces a variety of potent antioxidants, including hydroxytyrosol, oleuropein, and tyrosol, that have been widely used in agriculture, pharmacy, and cosmetics. This study aims to design new poly(guanamine)s phases by polycondensation of modified triazine monomers with both petro-based and biosourced diamines, to act as stationary phases for the uptake of these phenolic molecules. Obtained polymers were characterized by NMR spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The adsorption results showed that the newly synthesized polymers can effectively uptake the less polar phenolic compounds, ferulic acid, and caffeic acid. The isosorbide-based polymer (P6) presented the highest sorption efficiency, due to the hydrophilic properties of isosorbide associated with the proton affinity of the triazine groups. All the phenolic compounds were successfully desorbed from the P6 polymer using a minimal amount of a methanol/acetonitrile mixture. P6 polymer could be used for four successive adsorption processes without loss of efficiency.
KW - Olive mill wastewater
KW - Triazine
KW - Isosorbide
KW - Adsorption
KW - Phenolic compounds
PY - 2024
DO - https://doi.org/10.1007/s42250-024-01081-3
SN - 2522-5758
SP - 1
EP - 11
PB - Springer Science and Business Media LLC
AN - OPUS4-61348
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Trimpin, Sarah
A1 - Yenchick, Frank S.
A1 - Lee, Chuping
A1 - Hoang, Khoa
A1 - Pophristic, Milan
A1 - Karki, Santosh
A1 - Marshall, Darrell D.
A1 - Lu, I-Chung
A1 - Lutomski, Corinne A.
A1 - El-Baba, Tarick J.
A1 - Wang, Beixi
A1 - Pagnotti, Vincent S.
A1 - Meher, Anil K.
A1 - Chakrabarty, Shubhashis
A1 - Imperial, Lorelei F.
A1 - Madarshahian, Sara
A1 - Richards, Alicia L.
A1 - Lietz, Christopher B.
A1 - Moreno-Pedraza, Abigail
A1 - Leach, Samantha M.
A1 - Gibson, Stephen C.
A1 - Elia, Efstathios A.
A1 - Thawoos, Shameemah M.
A1 - Woodall, Daniel W.
A1 - Jarois, Dean R.
A1 - Davis, Eric T.J.
A1 - Liao, Guochao
A1 - Muthunayake, Nisansala S.
A1 - Redding, McKenna J.
A1 - Reynolds, Christian A.
A1 - Anthony, Thilani M.
A1 - Vithanarachchi, Sashiprabha M.
A1 - DeMent, Paul
A1 - Adewale, Adeleye O.
A1 - Yan, Lu
A1 - Wager-Miller, James
A1 - Ahn, Young-Hoon
A1 - Sanderson, Thomas H.
A1 - Przyklenk, Karin
A1 - Greenberg, Miriam L.
A1 - Suits, Arthur G.
A1 - Allen, Matthew J.
A1 - Narayan, Srinivas B.
A1 - Caruso, Joseph A.
A1 - Stemmer, Paul M.
A1 - Nguyen, Hien M.
A1 - Weidner, Steffen
A1 - Rackers, Kevin J.
A1 - Djuric, Ana
A1 - Shulaev, Vladimir
A1 - Hendrickson, Tamara L.
A1 - Chow, Christine S.
A1 - Pflum, Mary Kay H.
A1 - Grayson, Scott M.
A1 - Lobodin, Vladislav V.
A1 - Guo, Zhongwu
A1 - Ni, Chi-Kung
A1 - Walker, J. Michael
A1 - Mackie, Ken
A1 - Inutan, Ellen D.
A1 - McEwen, Charles N.
T1 - New Processes for Ionizing Nonvolatile Compounds in Mass Spectrometry: The Road of Discovery to Current State-of-the-Art
N2 - This Perspective covers discovery and mechanistic aspects aswell as initial applications of novel ionization processes for use in massspectrometry that guided us in a series of subsequent discoveries, instrumentdevelopments, and commercialization. Vacuum matrix-assisted ionization onan intermediate pressure matrix-assisted laser desorption/ionization sourcewithout the use of a laser, high voltages, or any other added energy wassimply unbelievable, at first. Individually and as a whole, the variousdiscoveries and inventions started to paint, inter alia, an exciting new pictureand outlook in mass spectrometry from which key developments grew thatwere at the time unimaginable, and continue to surprise us in its simplisticpreeminence. We, and others, have demonstrated exceptional analyticalutility. Our current research is focused on how best to understand, improve, and use these novel ionization processes throughdedicated platforms and source developments. These ionization processes convert volatile and nonvolatile compounds from solid orliquid matrixes into gas-phase ions for analysis by mass spectrometry using, e.g., mass-selected fragmentation and ion mobilityspectrometry to provide accurate, and sometimes improved, mass and drift time resolution. The combination of research anddiscoveries demonstrated multiple advantages of the new ionization processes and established the basis of the successes that lead tothe Biemann Medal and this Perspective. How the new ionization processes relate to traditional ionization is also presented, as wellas how these technologies can be utilized in tandem through instrument modification and implementation to increase coverage ofcomplex materials through complementary strengths.
KW - Mass spectrometry
PY - 2024
DO - https://doi.org/10.1021/jasms.3c00122
SN - 1879-1123
VL - 35
IS - 12
SP - 2753
EP - 2784
PB - American Chemical Society (ACS)
AN - OPUS4-61417
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dalgic, Mete-Sungur
A1 - Weidner, Steffen
T1 - Solvent-free sample preparation for matrix-assisted laserdesorption/ionization time-of-flight mass spectrometry ofpolymer blends
N2 - Solvent-free sample preparation offers some advantages over solvent-based techniques, such as improved accuracy, reproducibility and sensitivity, for matrix-assisted laser desorption/ionization (MALDI) analysis. However, little or no information is available on the application of solvent-free techniques for the MALDI analysis of polymer blends. Solvent-free sample preparation by ball milling was applied with varying sample-to-matrix ratios for MALDI time-of-flight mass spectrometry analysis of various polymers, including polystyrenes, poly(methyl methacrylate)s and poly(ethylene glycol)s. The peak intensity ratios were compared with those obtained after using the conventional dried droplet sample preparation method. In addition, solvent-assisted milling was also applied to improve sample homogeneities.
Depending on the sample preparation method used, different peak intensity ratios were found, showing varying degrees of suppression of the signal intensities of higher mass polymers. Ball milling for up to 30 min was required to achieve constant intensity ratios indicating homogeneous mixtures. The use of wet-assisted grinding to improve the homogeneity of the blends was found to be disadvantageous as it caused partial degradation and mass-dependent segregation of the polymers in the vials.The results clearly show that solvent-free sample preparation must be carefully considered when applied to synthetic polymer blends, as it may cause additional problems with regard to homogeneity and stability of the blends.
KW - MALDI TOF MS
KW - Sample preparation
KW - Polymer blends
KW - Solvent-free
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598570
DO - https://doi.org/10.1002/rcm.9756
SN - 0951-4198
VL - 38
IS - 12
SP - 1
EP - 9
PB - Wiley online library
AN - OPUS4-59857
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - Ring-ring equilibration (RRE) of cyclic poly(L-lactide)s by means of cyclic tin catalysts
N2 - With 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzoxepane (SnBiPh) as catalysts ring-expansion polymerizations (REP) were performed either in 2 M solution using three different solvents and two different temperatures or in bulk at 140 and 120 ◦C. A kinetically controlled rapid REP up to weight average molecular masses (Mẃs) above 300 000 was followed by a slower degradation of the molecular masses at 140 ◦C, but not at 120 ◦C Furthermore, a low molecular mass cyclic poly(L-lactide) (cPLA) with a Mn around 16 000 was prepared by polymerization in dilute solution and used as starting material for ring-ring equilibration at 140 ◦C in 2 M solutions. Again, a decrease of the molecular mass was detectable, suggesting that the equilibrium Mn is below 5 000. The degradation of the molecular masses via RRE was surprisingly more effective in solid cyclic PLA than in solution, and a specific transesterification mechanism involving loops on the surface of crystallites is proposed. This degradation favored the formation of extended-ring crystallites, which were detectable by a “saw-tooth pattern” in their MALDI mass spectra.
KW - Organic Chemistry
KW - Polymers and Plastics
KW - MALDI-TOF MS
KW - Materials Chemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593819
DO - https://doi.org/10.1016/j.eurpolymj.2024.112765
SN - 0014-3057
VL - 206
SP - 1
EP - 8
PB - Elsevier B.V.
AN - OPUS4-59381
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Falkenhagen, Jana
A1 - Kricheldorf, H. R.
T1 - Polycondensations and Cyclization of Poly(L-lactide) Ethyl Esters in the Solid State
N2 - The usefulness of seven different Tin catalysts, Bismuth subsalicylate and Titan tetra(ethoxide) for the polycondensation of ethyl L-lactate (ELA) was examined at 150 °C/6 d. Dibutyltin bis(phenoxides) proved to be particularly effective. Despite the low reactivity of ELA, weight average molecular masses (Mw) up to 12 500 were found along with partial crystallization. Furthermore, polylactides (PLAs) of similar molecular masses were prepared via ELA-initiated ROPs of L-lactide by means of the four most effective polycondensation catalysts. The crystalline linear PLAs were annealed at 140 or 160 °C in the presence of these catalysts. The consequences of the transesterification reactions in the solid PLAs were studied by means of matrix-assisted laser desorption/ionization (MALDI TOF) mass spectrometry, gel permeation chromatography (GPC) and small-angle X-ray scattering (SAXS). The results indicate that polycondensation and formation of cycles proceed in the solid state via formation of loops on the surface of the crystallites. In summary, five different transesterification reactions are required to explain all results.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592934
DO - https://doi.org/10.1039/d3py01232h
SN - 1759-9962
VL - 15
IS - 2
SP - 71
EP - 82
PB - RSC Publ.
CY - Cambridge
AN - OPUS4-59293
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Weidner, Steffen
T1 - MALDI TOF MS zur Aufklärung von Kristallisationsprozessen in Polyestern
N2 - MALDI TOF Massenspektrometrie wurde verwendet, um Kristallisationsprozesse in Polyestern (Polylactide, Polyglycolide) zu untersuchen. Dabei konnte gezeigt werden, dass Zyklen und Linearen simultan, aber in unterschiedlichen Kristalliten, kristallisieren. Die dabei ablaufenden Umesterungen (Transesterifizierungen) konnten mit der MALDI TOF Massenspektrometrie nachgewiesen werden. Damit wurde ein völlig neues Anwendungsgebiet dieser MS Methode demonstriert.
T2 - 28. Kolloquium Massenspektrometrie von Polymeren
CY - Berlin, Germany
DA - 14.05.2024
KW - MALDI TOF MS
KW - Bioabbaubare Polymere
KW - Crystallinity
PY - 2024
AN - OPUS4-60029
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
T1 - Alcohol-Initiated and SnOct2-Catalyzed Ring-Opening Polymerization (ROP) of L-Lactide in Solution: A Re-investigation
N2 - Alcohol-initiated ring-opening polymerizations (ROP) of L-lactide (LA) were studied in solution at 70 °C, whereupon the nature of the alcohol, the LA/initiator ratio, the LA/SnOct2 ratio and the time were varied. In contrast to literature, neat SnOct2 is catalytically active in THF and several aromatic but donor solvents, such as 1,3-dioxolane, dimethylformamide (DMF) or N-methyl pyrrolidone (NMP), strongly reduce the activity of SnOct2. In agreement with literature, no cycles were formed by neat SnOct2 at 70 °C in toluene, whereas almost complete cyclization occurs at 115 °C. This finding is attributed to strongly reduced mobility of the initially formed linear chains having one Sn-O-CH and one anhydride end group. Due to better solvation and enhanced mobility cyclization occurs in THF at 70 °C.
KW - Polylactide
KW - Ring-opening polymerization
KW - MALDI-TOF MS
KW - Transesterification
PY - 2023
DO - https://doi.org/10.1016/j.eurpolymj.2023.111822
SN - 0014-3057
SP - 1
EP - 18
PB - Elsevier
CY - New York, NY [u.a.]
AN - OPUS4-56818
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Scheliga, F.
A1 - Weidner, Steffen
T1 - Syntheses of Cyclic Poly(l-lactide)s by Means of Zinc-Based Ring-Opening Polymerization with Simultaneous Polycondensation (ROPPOC) Catalysts
N2 - Ring-opening polymerizations of l-lactide are studied in bulk at 140 or 160 °C with zinc n-hexanoate, zinc 4-chlorothiophenolate, and zinc pentafluoro thiophenolate (ZnSPF) as catalysts. The reactivity increases in the given order.
With all three catalysts a high fraction of cycles is obtained only at polymerization (annealing) times around 7 d. With ZnSPF weight average molecular weights (Mw) up to 178 000, a Tm around 199 °C and a 𝚫Hm around 99 J g−1 were achieved. The samples annealed for 4 or 7 d also display a saw tooth pattern of the mass peak distribution in the matrix-assisted laser desorption/ionization time of flight spectra indicating transesterification reactions across the surface of extended ring crystals. This process optimizes the thermodynamical properties of the crystalline cyclic polylactides and is responsible for the high Tm and 𝚫Hm values.
KW - Polylactide
KW - MALDI-TOF MS
KW - Ring opening polymerization
KW - Polymerization
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578264
DO - https://doi.org/10.1002/macp.202300070
SN - 1022-1352
SP - 202300070
PB - Wiley VHC-Verlag
AN - OPUS4-57826
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
T1 - Cyclic and linear poly(L-lactide)s by ring-expansion polymerization with Bu2SnO, Oct2SnO, and Bu2SnS
N2 - To elucidate the usefulness of commercial Bu2SnO as catalyst for syntheses of linear and/or cyclic polylactides L-Lactide was polymerized in bulk with variation of the LA/Cat ratio, temperature and time. Based on a ring-expansion polymerization (REP) mechanism cyclic polylactides (PLAs) with weight average molecular weights in the range of 200,000–300,000 are obtained at the highest temperature (180 °C). Polymerizations at 150 °C yielded crystalline, mainly cyclic polylactides which, after annealing, showed high melting temperatures (up to 197.5 °C) and high crystallinities (>80%). Polymerization at 120 °C confirmed the trend towards more linear chains with lower temperatures but yielded extended-ring crystals showing a “saw-tooth pattern” in the mass spectra. Oct2SnO gave similar results as Bu2SnO. Bu2SnS proved a sluggish polymerization catalyst, but a good transesterification catalyst in solid PLA.
KW - MALDI TOF MS
KW - Biobased polymers
KW - Polylactide
KW - Ring-expansion polymerization
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584121
DO - https://doi.org/10.1002/pol.20230515
SN - 2642-4169
SP - 1
EP - 10
PB - Wiley
CY - Hoboken, NJ
AN - OPUS4-58412
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About the Influence of (Non-)Solvents on the Ring Expansion Polymerization of l-Lactide and the Formation of Extended Ring Crystals
N2 - Ring-expansion polymerizations (REPs) catalyzed by two cyclic tin catalysts (2-stanna-1.3-dioxa-4,5,6,7-dibenzazepine [SnBiph] and
2,2-dibutyl-2-stanna-1,3-dithiolane [DSTL]) are performed at 140 °C in bulk.
Small amounts (4 vol%) of chlorobenzene or other solvents are added to
facilitate transesterification reactions (ring–ring equilibration) in the solid poly(l-lactide)s. In the mass range up to m/z 13 000 crystalline PLAs displaying a so-called saw-tooth pattern in the MALDI-TOF mass spectra are obtained indicating the formation of extended-ring crystals. The characteristics of extended-ring crystallites and folded-ring crystallites are discussed. Furthermore, extremely high melting temperatures (Tm’s up to 201.2 °C) and melting enthalpies (𝚫Hm’s up to 106 J g−1)) are found confirming that 𝚫Hm max, the 𝚫Hm of a perfect crystal, is around or above 115 J g−1 in contrast to literature data.
KW - Polylactide
KW - MALDI-TOF MS
KW - Ring-expansion polymerization
KW - Biobased
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573063
DO - https://doi.org/10.1002/macp.202200385
VL - 224
IS - 5
SP - 1
EP - 8
PB - Wiley VHC-Verlag
AN - OPUS4-57306
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Becker, Roland
A1 - Scholz, Philipp
A1 - Jung, Christian
A1 - Weidner, Steffen
T1 - Thermo-Desorption Gas Chromatography-Mass Spectrometry for investigating the thermal degradation of polyurethanes
N2 - Thermo-Desorption Gas Chromatography-Mass Spectrometry (TD-GC-MS) was used to investigate the thermal degradation of two different polyurethanes (PU). PU samples were heated at different heating rates and the desorbed products were collected in a cold injection system and thereafter submitted to GC-MS. Prospects and limitations of the detection and quantification of semi-volatile degradation products were investigated. A temperature dependent PU depolymerization was
found at temperatures above 200 °C proved by an increasing release of 1,4-butanediol and methylene diphenyl diisocyanate (MDI) representing the main building blocks of both polymers. Their release was monitored quantitatively based on external calibration with authentic compounds. Size Exclusion Chromatography (SEC) of the residues obtained after thermodesorption confirmed the initial competitive degradation mechanism indicating an equilibrium of crosslinking and depolymerization as previously suggested. Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry of SEC fractions of thermally degraded PUs provided additional hints on degradation mechanism.
KW - Thermo-desorption
KW - Mass spectrometry
KW - Polyurethanes
KW - Thermal degradation
PY - 2023
DO - https://doi.org/10.1039/D3AY00173C
SN - 1759-9660
SP - 1
EP - 6
PB - Royal Society for Chemistry
AN - OPUS4-57307
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Jaffrezic-Renault, N.
A1 - Weidner, Steffen
A1 - Marestin, C.
A1 - Mercier, R.
T1 - Impedimetric sensors based on diethylphosphonate-containingpoly(arylene ether nitrile)s films for the detection of lead ions
N2 - This article describes the elaboration and characterization of diethylphosphonate-containing polymers coated electrodes as sensors for the detection of heavy metalstraces, by electrochemical impedance spectroscopy. Diethylphosphonate groupswere chosen as heavy metals binding sites. Two different series of polymers bearingthese anchoring groups were synthesized. Whereas the diethylphosphonate groupsare directly incorporated in the aromatic macromolecular chain in some polymers, analiphatic spacer is removing the chelating site from the polymer backbone in others.The influence of the macromolecular structure on the sensing response was studied,especially for the detection of Pb2+,Ni2+,Cd2+and Hg2+. Polymer P6, including thehigher amount of diethylphosphonate groups removed from the polymer chain by ashort alkyl spacer gave the higher sensitivity of detection of lead ions, with a detec-tion limit of 50 pM
KW - Heavy metals
KW - Phosphonate esters
KW - Lead ions
KW - MALDI TOF MS
PY - 2023
DO - https://doi.org/10.1002/pat.6065
SN - 1042-7147
SP - 1
EP - 11
PB - John Wiley & Sons, Ltd
AN - OPUS4-57356
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H. R.
T1 - Alcohol-initiated and Tin(II) 2-ethylhexanoate-catalyzed polymerization of L-lactide in bulk – About separate crystallization of cyclic and linear Poly (L-lactide)s
N2 - Alcohol-initiated ROPs of L-Lactide were performed at 140 ◦C in bulk with variation of the initiator/catalyst ratio and time. Lower ratios favor the formation of cycles which upon annealing display a change of the MALDI mass peak distribution towards a new maximum with a “saw-tooth pattern” of the mass peaks representing the cycles.
Such a pattern was not observed for the mass peak of the linear chains. The coexistence of these patterns indicate that linear and cyclic poly (L-lactide)s (PLA) crystallize in separate crystals, and that the crystallites of the cycles are made up by extended rings. High Tm and ΔHm values confirm that these extended-ring crystallites represent a thermodynamically optimized form of PLA. Experiments with preformed cyclic and linear PLAs support this interpretation.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
KW - Polymerization
PY - 2023
DO - https://doi.org/10.1016/j.polymer.2023.126355
VL - 285
IS - 126355
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-58355
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
T1 - About the crystallization of cyclic and linear poly(L-lactide)s in alcohol-initiated and Sn(II)2-ethylhexanoate- catalyzed ROPs of L-lactide conducted in solution
N2 - 1-Hydroxymethylnaphtalene (HMN) or 11-bromoundecanol (BUND) were used as initiators and Sn(II) 2-ethylhexanoate (SnOct2) as catalyst for ROPs of L-Lactide (LA) at 115 °C in bulk or in 4 M and 2M solutions in toluene. The LA/In ratio, the LA/Cat ratio and the time were varied. The matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectra exclusively displayed peaks of linear chains, when the ROPs were conducted in bulk. But in contrast to reports in the literature, mixtures of linear and cyclic poly(L-lactide) (PLA), were obtained, when the ROPs were performed in solution. The intensity distribution of the mass peaks of cyclic PLAs displayed a “saw-tooth pattern” after annealing in contrast to the mass peak distribution of the liner chains. This new phenomenon indicated that cyclic PLAs and linear PLAs crystallized in separate crystals from the same reaction mixture. This conclusion was confirmed by fractionated crystallization from 2 M solution, which confirmed that the cyclic PLAs nucleate and crystallize faster than the linear chains.
KW - Polylactide
KW - MALDI-TOF MS
KW - Ring opening polymerization
KW - Crystallization
PY - 2023
DO - https://doi.org/10.1016/j.polymer.2023.125946
SN - 0032-3861
VL - 276
SP - 1
EP - 11
PB - Elsevier Ltd.
AN - OPUS4-57308
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H. R.
T1 - Sn(II)2-ethylhexanoate-catalyzed polymerizations of L-lactide in solution – Solution grown crystals of cyclic Poly(L-Lactide)s
N2 - L-lactide (LA) was polymerized in toluene by means of neat tin(II) 2-ethylhexanoate (SnOct2). Concentration, time and temperature were varied. The isothermally crystallized polyLAs (PLA) were characterized in the virgin state with regard to topology, molar mass, melting temperature (Tm), crystal modification, high or low Tm morphology, crystallinity and crystal thickness. Even a small amount of solvent favored cyclization relative to polymerization in bulk, so that cyclic polylactides were obtained at 115 ◦C and even at 95 ◦C. At all temperatures the α-modification of PLA was obtained along with crystallinities up to 90%. With 6 M solution the high Tm morphology with Tm’s > 190 ◦C was obtained at 115 ◦C. The crystal thickness of crystallites grown from solution at 115 ◦C was on the average 10–20% higher than that of PLA polymerized in bulk. At a polymerization temperature of 75 ◦C cyclization was incomplete and fewer perfect crystallites were formed. A new hypothesis for the crystal growth of cyclic polyLAs is proposed.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
KW - Polymerization
PY - 2022
DO - https://doi.org/10.1016/j.polymer.2022.125142
SN - 0032-3861
VL - 255
SP - 1
EP - 9
PB - Elsevier
CY - Oxford
AN - OPUS4-55283
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Weidner, Steffen
T1 - MALDI-ToF mass spectrometry for the characterization of biobased polymers suitable for depollution
N2 - In this work, bio-based polymers were synthesized and designed as polymers phases for adsorption of a variety of pollutants from aqueous solutions. The obtained adsorption results showed that the integration of bio-sourced synthons generate attractive hydrophilicity, and wettability of the resulting adsorbent phase. Such polymers phases enable stronger interactions with the organic and inorganic pollutants in water.
A wide variety of different bio-based polymers structures (e. g. poly(ethersulfones, poly(etherphosphines or poly(etherpyridines) with different functional groups were successfully designed in order to adapt chemical structure to different pollutants type and matrice nature.
In order to characterize and to determine the correlation between polymer structures and nature of interaction with pollutants, different analytical technics (NMR, GPC, ATG, DSC, Mass spectrometry) were successfully used. Amongst them, MALDI TOF mass spectrometry plays a superior role since this technique enables the simultaneous determination of the polymer structure, polymer end groups and molecular weight.
This work focusses on the characterization of synthesized polymers. The chemical structure of the repeating unit, the nature of the end groups, as well as the molecular weight, which are all important for the specific interactions of the polymer with the pollutants were clearly determined and suggestions to improve these interactions by changing the synthetic pathway could be given.
T2 - 12. Journees maghreb-europe. Matériaux et Applications aux Dispositifs et Capteurs
CY - Monastir, Tunisia
DA - 08.11.2022
KW - MALDI TOF MS
KW - Biobased polymers
KW - Depollution
PY - 2022
AN - OPUS4-56237
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Brirmi, M
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Schiets, F.
A1 - Casabianca, H.
A1 - Marestin, C.
A1 - Mercier, R.
A1 - Weidner, Steffen
A1 - Errachid, A.
A1 - Jaffrezic-Renault, N.
A1 - Ben Romdhane, H.
T1 - Effect of the pendent groups on biobased polymers, obtained from click chemistry suitable, for the adsorption of organic pollutants from water
N2 - In this work, four triazole-based poly(ether-pyridine)s polymers were synthesized and used as an adsorbent for the removal of phenolic compounds from aqueous solutions. For this purpose, new fluoromonomers containing 1,2,3-triazole units were prepared by the Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction and then used for the elaboration of novel poly(ether-pyridine-triazole)s (PEPTs) by direct polyconden-sation with isosorbide and bisphenol A. Chemical structure of fluorinated pyridinicmonomers as well as resulting polymers was confirmed by 1H and 19F NMR spectroscopic methods. The thermal behavior of the obtained PEPTs was characterized using differential scanning calorimetry and thermogravimetric analysis. Results of sorption showed that polymers can be effectively used as a sorbent for the removal of polarorganic pollutants. The isosorbide-based poly(ether-pyridine-triazole) which contains hydrophilic hydroxyl groups as pendants chains (P4) exhibited the highest sorption efficiencies (78%–100% after 1 h). In order to explain the results an adsorption mech-anism mainly based on π–π interactions and hydrogen bonding with the pendent groups is proposed.
KW - Adsorption
KW - Biobased polymers
KW - Cycloaddition
KW - Pentafluoropyridine
KW - Phenolic compounds
PY - 2022
DO - https://doi.org/10.1002/pat.5809
SN - 1042-7147
SP - 1
EP - 21
PB - Wiley online library
AN - OPUS4-55389
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Ring-expansion polymerization (REP) of L-lactide with cyclic tin catalysts – About formation of extended ring crystals and optimization of Tm and ΔHm
N2 - L-Lactide was polymerized in bulk at 140 °C with three different cyclic tin catalysts and the time was varied from 1 d up to 14 d. The MALDI TOF spectra confirmed the formation of cyclic polylactides (PLAs) and displayed a characteristic change of peak intensity distribution with formation of a “saw tooth pattern”. This pattern confirms a previous hypothesis that cyclic PLAs tend to form crystallites with extended ring conformation and relatively smooth surface. This type of crystallites is formed under thermodynamic control by transesterification on the surface of the crystallites. In this way PLAs with extraordinarily high melting temperatures (Tm's up to 200.6 °C) and extraordinarily high melting enthalpy were obtained (ΔHm's up to 105 J g−1). These ΔHm values require a revision of the maximum ΔHm value calculated in the literature for ideal PLA crystals.
KW - Polylactide
KW - MALDI-TOF MS
KW - ring-expansion polymerization
PY - 2022
DO - https://doi.org/10.1016/j.polymer.2022.125516
SN - 0032-3861
VL - 263
SP - 125516
PB - Elsevier Ltd.
AN - OPUS4-56338
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Scheliga, F.
T1 - Ring-opening polymerizations of L-Lactide catalyzed by zinc caprylate: Syntheses of cyclic and linear poly(L-lactide)s
N2 - Alcohol-initiated ring-opening polymerizations (ROPs) of L-Lactide (LA) were conducted in bulk at 130 °C catalyzed by Zn acetate (ZnAc2), lactate (ZnLac2), or caprylate (ZnCap2). 11-undecenol (UND), 1-hydroxymethylnaphtalene (HMN), and 4-nitrobenzylalcohol (4NB) were used as alcohols. Whereas variation of the alcohols had little effect, the usefulness of the catalysts increased in the order: acetate < lactate < caprylate. Hence, further alcohol-initiated polymerizations were performed with ZnCap2 alone and with variation of the lactide/catalyst (LA/Cat) ratio. With increasing LA/Cat ratio higher fractions of cyclic poly(L-lactide) (PLA) were found, so that the measured degree of polymerization (DP) is considerably lower than the theoretical value (i.e., 2 x LA/alcohol). With neat ZnCap2 cyclic PLAs were the largely prevailing reaction products. For these cyclic PLAs weight average molar masses (Mw) up to 134,000 were obtained and an optical purity around 99% was indicated by 13C NMR spectroscopy and DSC measurements even after 48 h at 150 or 160 °C.
KW - Cyclization
KW - Lactide
KW - Ring opening polymerization
KW - Transesterification
KW - Zinc catalyst
KW - MALDI
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557565
DO - https://doi.org/10.1002/pol.20220328
SN - 2642-4150
SP - 1
EP - 10
PB - Wiley
AN - OPUS4-55756
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About the Influence of (Non-)Solvents on the Ring Expansion Polymerization of l-Lactide and the Formation of Extended Ring Crystals
N2 - Ring-expansion polymerizations (REPs) catalyzed by two cyclic tin catalysts(2-stanna-1.3-dioxa-4,5,6,7-dibenzazepine [SnBiph] and
2,2-dibutyl-2-stanna-1,3-dithiolane [DSTL) are performed at 140 °C in bulk.
Small amounts (4 vol%) of chlorobenzene or other solvents are added to facilitate transesterification reactions (ring–ring equilibration) in the solid poly(l-lactide)s. In the mass range up to m/z 13 000 crystalline PLAs displaying a so-called saw-tooth pattern in the MALDI-TOF mass spectra are obtained indicating the formation of extended-ring crystals. The characteristics of extended-ring crystallites and folded-ring crystallites are discussed. Furthermore, extremely high melting temperatures (Tm’s up to 201.2 °C) and melting enthalpies (𝚫Hm’s up to 106 J g−1)) are found confirming that 𝚫Hmmax, the 𝚫Hm of a perfect crystal, is around or above 115 J g−1 in contrast to literature data.
KW - Polylactide
KW - MALDI-TOF MS
KW - Ring-expansion polymerization
KW - Crystals
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565038
DO - https://doi.org/10.1002/macp.202200385
SN - 1022-1352
SP - 1
EP - 8
PB - Wiley VHC-Verlag
AN - OPUS4-56503
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Zouaoui, F.
A1 - Jlalia, A.
A1 - Gaiji, H.
A1 - Abderrazak, H.
A1 - Casablanca, H.
A1 - Mercier, R.
A1 - Weidner, Steffen
A1 - Errachid, A.
A1 - Marestin, C.
A1 - Jaffrezic-Renault, N.
T1 - New poly(ether-phosphoramide)s sulfides based on green resources as sensitive films for the specific impedimetric detection of nickel ions
N2 - For the development of selective and sensitive chemical sensors, we have developed a new family of poly(etherphosphoramide) polymers. These polymers were obtained with satisfactory yields by nucleophilic aromatic polycondensation using isosorbide as green resources, and bisphenol A with two novel difluoro phosphinothioic amide monomers. Unprecedented, the thiophosphorylated aminoheterocycles monomers, functionalized with two heterocyclic amine, N-methylpiperazine and morpholine were successfully obtained by nucleophilic substitution reaction of P(S)–Cl compound. The resulting polymers were characterized by different analytical techniques (NMR, MALDI–ToF MS, GPC, DSC, and ATG). The resulting partially green polymers, having tertiary phosphine sulfide with P–N side chain functionalities along the main chain of polymers are the sensitive film at the surface of a gold electrode for the impedimetric detection of Cd, Ni, Pb and Hg. The bio-based poly(etherphosphoramide) functionalized with N-methylpiperazine modified sensor showed better analytical performance
than petrochemical based polymers for the detection of Ni2+. A detection limit of 50 pM was obtained which is very low compared to the previously published electrochemical sensors for nickel detection.
KW - Poly(ether-phosphoramide)s sulfides
KW - Green chemistry
KW - Polymer film
KW - MALDI TOF MS
PY - 2022
DO - https://doi.org/10.1016/j.talanta.2022.123550
VL - 247
IS - 123550
SP - 1
EP - 9
PB - Elsevier B.V.
AN - OPUS4-54980
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
T1 - Synthesis of polylactides by means of tin catalysts
N2 - This article reviews the usefulness of tin(II) and tin(IV) salts and compounds as catalysts for the polymerization of lactides. The text is subdivided into nine parts mainly reflecting different polymerization strategies, such as ring-opening polymerization (ROP), ring-expansion polymerization (REP), ROP combined with simultaneous polycondensation (ROPPOC), various catalysts with unknown polymerization mechanisms, and polycondensation of lactic acid. Since the toxicity of tin salts and compounds is a matter of concern and frequently mentioned in numerous publications, the first section deals with facts instead of myths about the toxicity of tin salts and compounds.
KW - Polylactide
KW - MALDI-TOF MS
KW - Tin catalysts
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545050
DO - https://doi.org/10.1039/d2py00092j
SP - 1
EP - 30
PB - Royal Society for Chemistry
AN - OPUS4-54505
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Scheliga, F.
T1 - SnOct2-catalyzed and alcohol-initiated ROPS of L-lactide - Control of the molecular weight and the role of cyclization
N2 - Ring-opening polymerizations (ROP) of l-lactide (LA) are conducted in bulk at 130, 160, or 180 °C and are initiated with two different alcohols at 160 °C. The lactide/initiator ratio (LA/In) is varied from 50/1 (20/1 at 180 °C) to 900/1 and the lactide/catalyst ratio (LA/Cat) between 2000/1 and 8000/1. At all temperatures a nearly perfect control of number average molecular weight (Mn) via the LA/In ratio is feasible up to LA/In = 200/1, but at higher ratios the Mn value lags behind the theoretical values and the discrepancy increases with higher LA/Cat ratios. Variation of the LA/Cat ratio influences the formation of cycles but does not significantly influence Mn, when the LA/In ratio is kept constant. The formation of cycles is favored by lower In/Cat ratios and is the main reason for the unsatisfactory control of Mn at high LA/In ratios. The results also suggest that the cycles are mainly or exclusively formed by end-to-end cyclization and not, as believed previously, by back-biting.
KW - Polylactide
KW - MALDI-TOF MS
KW - Cyclization
KW - Ring-opening polymerization
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543066
DO - https://doi.org/10.1002/macp.202100464
SN - 1521-3935
SP - 1
EP - 10
PB - Wiley-VCH
CY - Weinheim
AN - OPUS4-54306
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Falkenhagen, Jana
T1 - The role of transesterifications in reversible polycondensations and a reinvestigation of the Jacobson-Beckmann-Stockmayer experiments
N2 - The polycondensations of adipic acid and 1,10-decanediol catalyzed by toluene sulfonic acid (TSA) were reinvestigated using MALDI TOF mass spectrometry and NMR spectroscopy. Unexpected reactions of TSA were detected along with incomplete conversion of the monomers. Furthermore, transesterification reactions of end-capped poly(1,10-decanediol adipate) and end-capped poly(ε-caprolactone) catalyzed by TSA were studied. Despite the quite different (ionic) reaction mechanisms, it was found that for polycondensations performed in bulk intermolecular transesterification is more efficient than the intramolecular “back-biting”; this scenario was not considered in the Jacobson–Stockmayer theory of reversible polycondensations.
These results also confirm that the Jacobson–Stockmayer explanation of reversible polycondensations solely on the basis of ring chain equilibration is not only devoid of any experimental evidence, but also in contradiction to the results elaborated in this work.
KW - Polylactide
KW - MALDI-TOF MS
KW - Polycondensation
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543402
DO - https://doi.org/10.1039/d1py01679b
SN - 1759-9962
SP - 1
EP - 9
PB - RSC Publ.
CY - Cambridge
AN - OPUS4-54340
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mechichi, R.
A1 - Chabbah, T.
A1 - Chatti, S.
A1 - Jlalia, I.
A1 - Sanglar, Corinne
A1 - Casablanca, H.
A1 - Vulliet, E.
A1 - Marestin, C.
A1 - Mercier, R.
A1 - Weidner, Steffen
A1 - Errachid, A.
A1 - Hammani, M.
A1 - Jaffrezic-Renault, N.
A1 - Abderrazak, H.
T1 - Semi‑interpenetrating Network‑Coated Silica Gel Based on Green Resources for the Efcient Adsorption of Aromatic Pollutants from Waters
N2 - In the framework of the development of green analytical chemistry, a silica gel (SG) coated with a semi-penetrating network based on the partially biosourced poly(ethersulfone) is studied for a greener extraction process of aromatic organic pollutants. An optimized composition of the semi-penetrating network (80% of the linear polymer (LP): isosorbide-based poly(ethersulfone) and 20% cross-linking agent (XP) type bismaleimide) leads to a total adsorption of the selected aromatic pollutants, whatever their hydrophilicity. Adsorption characteristic, kinetics and isotherms of the SG-semi-INP LP80/XP20 for p-hydroxybenzoic acid and for toluic acid were studied. Langmuir model led to a better ftting of the adsorption isotherms; the adsorption of toluic acid is easier than that of p-hydroxybenzoic acid. 1/n values of benzoic acid was lower for SGsemi-INP LP80/XP20 compared to biochar and to cross-linked methacrylate resin, showing a higher adsorption efciency.
KW - Isosorbide
KW - Semi-interpenetrating networks
KW - Silica gel modification
KW - Aromatic pollutants
KW - Adsorption
PY - 2022
DO - https://doi.org/10.1007/s42250-022-00463
SN - 2522-5758
SP - 1
EP - 18
PB - Springer
AN - OPUS4-55720
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -