TY - JOUR A1 - Kricheldorf, H. A1 - Weidner, Steffen A1 - Scheliga, F. ED - Shaplov, A. T1 - Cyclization and dispersity of polyesters N2 - Two classes of polyesters were prepared by irreversible polycondensations. The dependence of the dispersities on the experimental parameters such as synthetic method, chemical structure, molecular weight and initial monomer concentration was determined. At first it was demonstrated that it is essential for a correct calculation of Mn and Mw to include all oligomers down to the dimers in the evaluation of SEC curves. Furthermore, it was demonstrated for poly(e-caprolactone)s and polylactides that reversible polycondensations and ring-opening polymerizations with equilibration yield identical products. Finally, the dependence of the dispersity on various experimental Parameters was determined for equilibrated poly(e-caprolactone)s and polylactides. KW - Irreversible polycondensation KW - Polycaprolactone KW - Polylactide KW - Dispersity KW - MALDI-TOF MS PY - 2017 DO - https://doi.org/10.1002/masy.201600169 SN - 1022-1360 SN - 1521-3900 VL - 375 IS - 1 SP - Article 1600169, 1 EP - 6 PB - Wiley-VCH AN - OPUS4-42407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. R. A1 - Weidner, Steffen T1 - Dispersities of Polyesters of Various Diphenols Prepared by Irreversible Polycondensations N2 - Polyesters of bisphenol-A, bisphenol-P, catechol, and sebacic acid are prepared and different synthetic methods are compared. The diphenols are condensed with sebacoyl chloride either in dichloromethane/pyridine or in refl uxing chlorobenzene without HCl-acceptor. Further- more, bisphenol-A acetate is polycondensed with sebacic acid in bulk. All experiments are worked up so that fractionation is avoided. The extent of cyclization is estimated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) and the molar mass distribution by size exclusion chromatography (SEC). Polycondensations in solution yield larger fractions of cyclics and higher dispersities (up to 11). Polycondensations in bulk give lower fractions of cycles and dispersities from 4.6 to 6.3 for high molar mass polyesters or 2.8 to 3.5 for low molar mass products. Characteristic curves describing the dependence of the dispersity on the initial monomer concentration are elaborated. KW - cyclization KW - dispersity KW - mass spectra KW - polycondensation KW - polyesters PY - 2016 DO - https://doi.org/10.1002/macp.201600004 IS - 217 SP - 1361 EP - 1369 PB - Wiley-VCH Verlag CY - Weinheim AN - OPUS4-37120 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Koprinarov, Ivaylo A1 - Weidner, Steffen A1 - Kühn, Gerhard ED - Schindel-Bidinelli, E. T1 - Umweltfreundliches Metallisieren von Kunststoffen durch Plasmavorbehandlung in einem geschlossenen Reaktor T2 - Swissbonding 97 ; 11. Internationales Symposium Klebtechnik und Umwelt ; 11th International Symposium Bonding and Sealing Technology CY - Rapperswil, Schweiz DA - 1997-05-26 PY - 1997 SP - 1(?) EP - 3(?) PB - SWIBOTECH CY - Rorbas AN - OPUS4-6994 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Falkenhagen, Jana T1 - Imaging mass spectrometry for examining localization of polymeric composition in matrix-assisted laser desorption/ionization samples N2 - The localization of polymeric composition in samples prepared for matrix-assisted laser desorption/ionization (MALDI) analysis has been investigated by imaging mass spectrometry. Various matrices and solvents were used for sample spot preparation of a polybutyleneglycol (PBG 1000). It was shown that in visibly homogeneous spots, prepared using the dried droplet method, separation between matrix and polymer takes place. Moreover, using -cyano-4-hydroxycinnamic acid (CCA) as matrix and methanol as solvent molecular mass separation of the polymer homologues in the spots was detectable. In contrast to manually spotted samples, dry spray deposition results in homogeneous layers showing no separation effects. KW - Imaging KW - MALDI TOF Massenspektrometrie KW - Polymere PY - 2009 DO - https://doi.org/10.1002/rcm.3919 SN - 0951-4198 SN - 1097-0231 VL - 23 IS - 5 SP - 653 EP - 660 PB - Wiley CY - Chichester AN - OPUS4-19622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Untersuchung von plasmamodifizierten Polymeren mit speziellen Analysenmethoden T2 - Abteilungsseminar, BAM, Abt. VI CY - Berlin, Germany DA - 1996-05-02 PY - 1996 AN - OPUS4-6411 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mühlhan, C. A1 - Weidner, Steffen A1 - Friedrich, Jörg Florian A1 - Nowack, H. T1 - Improvement of bonding properties of polypropylene by low-pressure plasma treatment PY - 1999 SN - 0257-8972 VL - 116-119 SP - 783 EP - 787 PB - Elsevier Science CY - Lausanne AN - OPUS4-6982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - MALDI-TOF-MS for the determination of polymerization mechanisms of biodegradable polymers N2 - Eine neue Art einer Ring-Expansion Polymerization (REP) von zyklischen Polylaktiden mittels neuer Katalysatoren wird präsentiert. MALDI-TOF Massenspektrometrie und andere analytische Techniken wurden zur Aufklärung des Mechanismus eingesetzt. Dabei zeigte sich, dass im Gegensatz zu anderen REP, ausschließlich zyklische Polymere gebildet wurden. Diese stellen neue Kandidatenmaterialien für zukünftige neue CRM dar. T2 - 22. MALDI-Kolloquium CY - Berlin, Germany DA - 15.05.2018 KW - MALDI-TOF MS KW - Polylaktid KW - Zyklen PY - 2018 AN - OPUS4-44835 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gabriel, Stefan A1 - Schwarzinger, C. A1 - Schwarzinger, B. A1 - Panne, Ulrich A1 - Weidner, Steffen T1 - Matrix segregation as the major cause for sample inhomogeneity in MALDI dried droplet spots N2 - The segregation in dried droplet MALDI sample spots was analyzed with regard to the matrix-to-sample ratio using optical microscopy, MALDI imaging mass spectrometry (MALDI MSI) and IR imaging spectroscopy. In this context, different polymer/matrix/solvent systems usually applied in the analysis of synthetic polymers were investigated. The use of typical matrix concentrations (10 mg mL-1) in almost every case resulted in ring patterns, whereas higher concentrated matrix solutions always led to homogeneous sample spot layers. The data revealed that segregation is predominantly caused by matrix transport in the drying droplet, whereas polymer segregation seems to be only secondary. KW - MALDI KW - Imaging MS KW - Matrix segregation KW - Dried droplet KW - Sample preparation KW - Polymers PY - 2014 DO - https://doi.org/10.1007/s13361-014-0913-0 SN - 1044-0305 VL - 25 IS - 8 SP - 1356 EP - 1363 PB - American Society for Mass Spectrometry CY - New York, NY AN - OPUS4-32582 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Improved analysis of ultra-high mass polymers in MALDI-TOF mass spectrometry T2 - ASMS 2015 CY - St. Louis (USA) DA - 2015-05-30 PY - 2015 AN - OPUS4-33446 LA - deu 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 - Cappella, Brunero A1 - Sturm, Heinz A1 - Weidner, Steffen T1 - Breaking polymer chains by dynamic plowing lithography N2 - The adhesion of poly(methyl methacrylate) (PMMA) and polystyrene (PS) films, whose surface has been previously structured by dynamic plowing lithography (DPL), has been measured by means of force–displacement curves. The different adhesion of modified and unmodified PS leads to the assumption that polymer chains are broken during DPL. After measuring the energy dissipated by the tip during DPL, in order to check that the transferred energy is sufficient to break covalent bonds, the polymer chain scission caused by the lithographic process has been definitely confirmed by size exclusion chromatography measurements of the lithographed films. KW - AFM KW - Nanolithography KW - Chain scission PY - 2002 DO - https://doi.org/10.1016/S0032-3861(02)00285-9 SN - 0032-3861 SN - 1873-2291 VL - 43 IS - 16 SP - 4461 EP - 4466 PB - Springer CY - Berlin AN - OPUS4-1608 LA - eng 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 - GEN A1 - Weidner, Steffen T1 - Rezension: Kompakte Zusammenfassung - MALDI-TOF Mass Spectrometry of Synthetic Polymers. Von H. Pasch, W. Schrepp. Springer, Heidelberg 2003, 298 Seiten. geb., 79,95 Euro. ISBN 3-540-44259-6 PY - 2003 DO - https://doi.org/10.1002/nadc.20030511123 SN - 1439-9598 SN - 1521-3854 VL - 51 IS - 11 SP - 1173 PB - Wiley-VCH CY - Weinheim AN - OPUS4-4678 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gross, J.H. A1 - Weidner, Steffen T1 - Influence of Electric Field Strength and Emitter Temperature on Field Desorption Mass Spectra of Polyethylene Oligomers N2 - The influence of electric field strength and emitter temperature on dehydrogenation and C–C cleavage in field desorption (FD) mass spectrometry of polyethylene (PE) oligomers of average molecular weights ranging from 500 to 2000 is examined. Low mass oligomers yield molecular weight (MW) distributions that are basically in accordance with results from gel-permeation chromatography. For these materials, dehydrogenation can be greatly reduced by reduction of the emitter potential. Furthermore, the influence of emitter potential on MW distributions indicates the occurrence of field-induced C–C cleavages. Reliable MW distributions are more difficult to obtain from higher mass oligomers by FD-MS because of the need for higher field strength and higher emitter temperatures to effect their desorption/ionization. Experiments reveal that the application of FD-MS to PE oligomers is limited not only by field-induced but also by thermally-induced fragmentations. Even then, FD mass spectra contain valuable information on mass range and homogeneity of PE samples up to about m/z 3600. PY - 2000 DO - https://doi.org/10.1255/ejms.300 SN - 1469-0667 SN - 1356-1049 SN - 1365-0718 IS - 6 SP - 11 EP - 17 PB - IM Publications CY - Chichester AN - OPUS4-11098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - MALDI von geregelten und ungeregelten Polyamiden nach kritischer Chromatographie T2 - VII. Anwendertreffen MALDI-TOF-MS zur Charakterisierung von synthetischen Polymeren CY - Berlin, Germany DA - 2002-05-14 PY - 2002 AN - OPUS4-11136 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Mechanism of homogeneously catalyzed polymerization of liquid-crystalline sidegroup monomers investigated by means of MALDI-TOF-MS (No. 433) T2 - 219th ACS National Meeting CY - San Francisco, CA, USA DA - 2000-03-26 PY - 2000 AN - OPUS4-11314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Beispiele für zweidimensionale Kopplungen von Chromatographie und MALDI-TOF-Massenspektrometrie zur Analyse von Polymeren T2 - BAM-Abt. VI-Seminar CY - Berlin, Germany DA - 2003-09-25 PY - 2003 AN - OPUS4-11139 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - SFC of new liquid-crystalline cholesteryl esters T2 - InCom '96, International Symposium on Instrumentalized Analytical Chemistry and Computer Technology CY - Düsseldorf, Germany DA - 1996-03-25 PY - 1996 AN - OPUS4-11194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Zengchao A1 - Jakubowski, Norbert A1 - Panne, Ulrich A1 - Weidner, Steffen T1 - Separation of polystyrene nanoparticles with different coatings using two-dimensional off-line coupling of asymmetrical flow field flow fractionation and capillary electrophoresis N2 - The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for separation of nanoparticles (NPs) with different surface coatings was shown. We could successfully demonstrate that, in a certain NP size range, hyphenation of both techniques significantly improved the separation of differently coated NPs. Three mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots in case of 20 and 50 nm particle mixtures, whereas the 100 nm NP mixture could not be separated at all. Various factors affecting the separation like hydrodynamic diameter or SDS concentration were discussed. KW - Capillary electrophoresis (CE) KW - Nanoparticles with same nominal diameter KW - Surface coating KW - Two-dimensional off-line coupling KW - Asymmetrical flow field flow fractionation (AF4) PY - 2019 DO - https://doi.org/10.1016/j.chroma.2019.01.056 VL - 1593 SP - 119 EP - 126 PB - Elsevier AN - OPUS4-47363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El Malah, T. A1 - Rolf, Simone A1 - Weidner, Steffen A1 - Thünemann, Andreas A1 - Hecht, S. T1 - Amphiphilic folded dendrimer discs and their thermosensitive self-assembly in water N2 - Folded dendrimers with peripheral ether side chains show a thermally induced hierarchical aggregation process, in which the transition temperature and the dimensions of the aggregates can readily be tuned via the generation number (see figure). KW - Click chemistry KW - Cotton effect KW - Dendrimers KW - Hierarchical self-assembly KW - Thermochemistry PY - 2012 DO - https://doi.org/10.1002/chem.201200414 SN - 0947-6539 SN - 1521-3765 VL - 18 IS - 19 SP - 5837 EP - 5842 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - Polymer characterization using sophisticated liquid chromatographic techniques combined with MALDI- and ESI-TOF mass spectrometry T2 - 55th ASMS conference on Mass Spectrometry CY - Indianapolis, IN, USA DA - 2007-06-03 PY - 2007 AN - OPUS4-14745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - LC-MALDI coupling for the analysis of polymers T2 - National Meeting of the Centre National de la Recherche Scientifique (CNRS) CY - Strasbourg, France DA - 2004-06-03 PY - 2004 AN - OPUS4-11308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -