TY - JOUR A1 - Kricheldorf, H. A1 - Probst, N. A1 - Schwarz, G. A1 - Schulz, Günter A1 - Krüger, Ralph-Peter T1 - New Polymer Syntheses - 107. Aliphatic Poly(thio ester)s by Ring-Opening Polycondensation of 2-Stanna-1,3-Dithiacycloalkanes N2 - We prepared 2,2-dibutyl-2-stanna-1,3-dithiacycloalkanes from dibutyltin oxide and ,-dimercaptoalkanes. Heterocycles with five-, six-, seven-, or nine-ring members were used as bifunctional monomers for polycondensations with aliphatic dicarboxylic acid chlorides. These polycondensations conducted in bulk were highly exothermic and yielded poly(thio ester)s with number average molecular weights (Mn's) in the range of 5000-30,000 Da. These poly(thio ester)s proved to be rapidly crystallizing materials with melting temperatures in the range of 90-150 °C. In addition to the success of the new synthetic approach, two interesting and unpredictable results were obtained. All volatile species detectable by matrix assisted laser desorption induced-time of flight (MALDI-TOF) mass spectrometry were cyclic oligo- and poly(thio ester)s. Second, several polyesters showed a reversible first-order change of the crystal modification as identified by differential scanning calorimetry measurements and X-ray scattering with variation of the temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3656-3664, 2000 KW - Poly(thio-ester)s KW - Ring-opening polycondensation KW - Macrocycles KW - Change of crystal structure PY - 2000 DO - https://doi.org/10.1002/1099-0518(20001001)38:19<3656::AID-POLA190>3.0.CO;2-M SN - 0360-6376 SN - 0887-624X VL - 38 IS - 19 SP - 3656 EP - 3664 PB - Wiley CY - Hoboken, NJ AN - OPUS4-2170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gähde, J. A1 - Mix, Renate A1 - Krüger, Ralph-Peter A1 - Goering, Harald A1 - Funke, W. A1 - Hermann, U. T1 - Adherence of Liquid Crystalline TDI-Polyurethanes to Steel KW - Main-chain liquid crystalline polyurethanes KW - Primer on steel KW - Pull-off test KW - Wet adhesion of alkyd melamine resin KW - Mesogenic unit KW - Glass transition temperature KW - Hard segments KW - Soft segments PY - 1996 SN - 0021-8464 SN - 1545-5823 VL - 58 SP - 243 EP - 251 PB - Gordon & Breach CY - New York, NY AN - OPUS4-2152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Spickermann, J. A1 - Martin, K. A1 - Räder, H.J. A1 - Müllen, K. A1 - Schlaad, H. A1 - Müller, A. H. E. A1 - Krüger, Ralph-Peter T1 - Quantitative analysis of broad molecular weight distributions obtained by MALDI-TOF mass spectrometry PY - 1996 SN - 1469-0667 SN - 1356-1049 SN - 1365-0718 IS - 2 SP - 161 EP - 165 PB - IM Publications CY - Chichester AN - OPUS4-2153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachsen, O. A1 - Reichert, K.H. A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Schulz, Günter T1 - Thermal decomposition of biodegradable polyesters - III. Studies on the mechanisms of thermal degradation of oligo-L-lactide using SEC, LACCC and MALDI-TOF-MS PY - 1997 SN - 0141-3910 SN - 1873-2321 VL - 55 SP - 225 EP - 231 PB - Applied Science Publ. CY - London AN - OPUS4-2154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tressl, R. A1 - Wondrak, G. T. A1 - Krüger, Ralph-Peter A1 - Rewicki, D. T1 - New Melanoidin-like Maillard Polymers from 2-Deoxypentoses KW - Maillard system 2-deoxy-D-ribose / methylamine KW - Oligomerization of N-methyl-2-hydroxymethyl(and hydroxyl[13C]methyl)pyrrole KW - Antioxidative activity KW - Model compounds for melanoidins PY - 1998 SN - 0021-8561 SN - 1520-5118 VL - 46 IS - 1 SP - 104 EP - 110 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-2158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tressl, R. A1 - Wondrak, G. T. A1 - Garbe, L.-A. A1 - Krüger, Ralph-Peter A1 - Rewicki, D. T1 - Pentoses and Hexoses as Sources of New Melanoidin-like Maillard-Polymers KW - Model compounds for melanoidins KW - Pyrroles from pentoses and hexoses KW - Beta-dicarbonyl pathway of the Maillard reaction KW - Polycondensation KW - MALDI-TOF-MS analysis KW - Antioxidative activity of oligomeric model compounds PY - 1998 SN - 0021-8561 SN - 1520-5118 VL - 46 IS - 5 SP - 1765 EP - 1776 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-2159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Böhme, S. A1 - Krüger, Ralph-Peter T1 - Macrocycles, 16a - Macrocyclic Dibutyltin Dicarboxylates via Thermodynamically Controlled Polycondensations N2 - Various dibutyltin derivatives were polycondensed with aliphatic ,-dicarboxylic acids having chain lengths from 4 (succinic acid) to 22 carbon atoms. White crystalline products were obtained from all experiments, and the structure of the products was independent of the synthetic method. Viscosity measurements revealed low molecular weights (n 1 500 Da) in all cases. Vapor pressure osmometry (VPO) measurements and matrix-assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometry proved that cyclic dimers and trimer were formed from dicarboxylic acids having 6 to 16 carbons, but mainly the monomeric cycle from docosane dioic acid. Heating to 250°C did not change the structure. Therefore, the results indicate that the macrocycles are the result of a thermodynamically controlled ring-closing polycondensation. This means that linear high-molecular weight poly(dibutyltin dicarboxylate)s cannot exist above room temperature. KW - Macrocyclics KW - MALDI KW - Oligomers KW - Polycondensation KW - Thermodynamics PY - 2002 SN - 1022-1352 SN - 1521-3935 VL - 203 IS - 2 SP - 313 EP - 318 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Ralph-Peter A1 - Kricheldorf, H.R. A1 - Böhme, S. T1 - Macrocycles 16. Macrocyclic Dibutyltin Dicarboxylates by Ring-Closing Polycondensation N2 - Various dibutyltin derivatives were polycondensed with aliphatic ,-dicarboxylic acids having chain lengths from 4 (succinic acid) to 22 carbon atoms. White crystalline products were obtained from all experiments, and the structure of the products was independent of the synthetic method. Viscosity measurements revealed low molecular weights (n 1 500 Da) in all cases. Vapor pressure osmometry (VPO) measurements and matrix-assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometry proved that cyclic dimers and trimer were formed from dicarboxylic acids having 6 to 16 carbons, but mainly the monomeric cycle from docosane dioic acid. Heating to 250°C did not change the structure. Therefore, the results indicate that the macrocycles are the result of a thermodynamically controlled ring-closing polycondensation. This means that linear high-molecular weight poly(dibutyltin dicarboxylate)s cannot exist above room temperature. PY - 2002 DO - https://doi.org/10.1002/1521-3935(20020101)203:2<313::AID-MACP313>3.0.CO;2-V SN - 1022-1352 SN - 1521-3935 VL - 203 IS - 2 SP - 313 EP - 318 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-1796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Ralph-Peter A1 - Kricheldorf, H.R. A1 - Böhme, S. T1 - Macrocyclic Dibutyltin Dicarboxylates via Thermodynamically Controlled Polycondensations KW - Macrocyclics KW - MALDI KW - Oligomers KW - Polycondensation KW - Thermodynamics PY - 2002 SN - 1022-1352 SN - 1521-3935 IS - 203 SP - 313 EP - 318 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-1656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grimm, B. A1 - Krüger, Ralph-Peter A1 - Schrader, S. A1 - Prescher, D. T1 - Molecular structure investigations on fluorine containing polyazomethines by means of the MALDI-TOF-MS technique N2 - Three new aromatic polyazomethines have been synthesized by solution polycondensation reactions of terephthalic dialdehyde with fluorine containing aromatic diamines. The polymers were obtained in high yields. The investigation of these polymers by means of matrix-assisted laser desorption ionization–time-of-flight–mass spectrometry (MALDI–TOF–MS) proved the initial members of the four theoretical possible series of the corresponding oligomers with 2–10 repeating units per molecule. KW - Polyazomethines KW - Oligomers KW - MALDI-TOF-MS PY - 2002 DO - https://doi.org/10.1016/S0022-1139(01)00498-5 SN - 0022-1139 SN - 1873-3328 VL - 113 SP - 85 EP - 91 PB - Elsevier CY - Amsterdam AN - OPUS4-1657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoebbel, D. A1 - Weber, Ch. A1 - Schmidt, H. A1 - Krüger, Ralph-Peter T1 - Synthesis and Properties of Perfluoroalkyl Groups Containing Double Four-Ring Spherosilicate (Siloxysilsesquioxane) Precursors N2 - Organically modified cage-like double four-ring spherosilicates have received considerable interest in the construction of nanosized hybrid materials, as well as building units for structural well-defined polymers. This group is extended by perfluoroalkyl ligands containing spherosilicates, synthesized by addition reaction of the octahydridodimethylsiloxyoctasilsesquioxane [H(CH3)2Si]8Si8O20 and heptadecafluorodecyl methacrylate. The resultant liquid spherosilicate substituted with eight terminal perfluoroalkyl groups was characterized by 29Si and 13C NMR spectroscopies and MALDI Time-of-Flight mass spectrometry. Partial substitution of perfluoroalkyl ligands by trimethoxysilyl containing groups provides condensable precursors for the synthesis of hydrophobic and oleophobic materials via the sol-gel process. This new spherosilicate, carrying on average four perfluoroalkyl groups and four trimethoxysilyl groups shows better hydrophobic and oleophobic properties compared with commonly used perfluoroalkyltrialkoxysilanes under identical concentration of perfluoroalkyl chains. In addition a comprehensive literature survey is given on structural well characterized, organically modified cage-like double four-ring spherosilicates. KW - Spherosilicate KW - Siloxysilsesquioxane KW - Perfluoralkylalkoxysilane KW - 29Si NMR KW - Coatings KW - Hydrophobicity PY - 2002 DO - https://doi.org/10.1023/A:1015239707783 SN - 0928-0707 SN - 1573-4846 VL - 24 SP - 121 EP - 129 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-1658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kukula, H. A1 - Schlaad, H. A1 - Krüger, Ralph-Peter A1 - Falkenhagen, Jana T1 - Improved Synthesis and Characterization of w-Primary Amino-Functional Polystyrenes and Polydienes PY - 2002 DO - https://doi.org/10.1021/ma0204397 SN - 0024-9297 SN - 1520-5835 VL - 35 IS - 18 SP - 7157 EP - 7160 PB - American Chemical Society CY - Washington, DC AN - OPUS4-1659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gloede, J. A1 - Pieper, U. A1 - Costisella, B. A1 - Krüger, Ralph-Peter T1 - Ein stabiles Trichlor-oxyphosphoran mit einem Oxaphosphorinring N2 - Das cyclische, arylsubstituierte Chlorphosphonit 3 reagiert mit Chlor zum Trichlor-oxyphosphoran 4 (6, 6, 6-Trichlor-6H-dibenzo[c, e]1, 2-oxaphosphorin). Die Stabilität des Phosphorans ist lösungsmittelabhängig. KW - Oxaphosphorines KW - Phosphoranes PY - 2003 DO - https://doi.org/10.1002/zaac.200200360 SN - 0044-2313 SN - 1521-3749 SN - 0372-7874 SN - 0863-1786 SN - 0863-1778 VL - 629 IS - 6 SP - 998 EP - 1000 PB - Wiley-VCH CY - Weinheim AN - OPUS4-2541 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schlaad, H. A1 - Müller, A. H. E. A1 - Kolshorn, H. A1 - Krüger, Ralph-Peter T1 - Mechanism of anionic polymerization of (meth)acrylates in the presence of aluminium alkyls PY - 1995 SN - 0170-0839 SN - 1436-2449 VL - 35 SP - 169 EP - 176 PB - Springer CY - Berlin AN - OPUS4-2144 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Schulz, Günter T1 - Determination of polymer heterogeneity by two-dimensional orthogonal liquid chromatography KW - Orthogonal chromatography KW - Size exclusion chromatography KW - Liquid adsorption chromatography at critical conditions KW - Matrix-assisted laser desorption ionization time-of-flight mass spectrometry KW - Polyester KW - Polyether PY - 1996 SN - 1023-666X SN - 1563-5341 VL - 2 SP - 221 EP - 235 PB - Gordon and Breach Publ. CY - Amsterdam AN - OPUS4-2146 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sonnenschein, H. A1 - Kreher, T. A1 - Gründemann, E. A1 - Krüger, Ralph-Peter A1 - Kunath, A. A1 - Zabel, V. T1 - Novel Redox-Active Cyclophanes Based on 3,3'-Bisindolizines - Synthesis and Chirality PY - 1996 SN - 0022-3263 SN - 1520-6904 VL - 61 SP - 710 EP - 714 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leukel, J. A1 - Burchard, W. A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Schulz, Günter T1 - Mechanism of the anionic copolymerization of anhydride- cured epoxies-analysisted by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) PY - 1996 SN - 1022-1336 SN - 1521-3927 VL - 17 SP - 359 EP - 366 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Vakhtangishvili, L. A1 - Schwarz, G. A1 - Schulz, Günter A1 - Krüger, Ralph-Peter T1 - Macrocycles 25. Cyclic poly(ether sulfone)s derived from 4-tert-butylcatechol N2 - Poly(ether sulfone)s were prepared by polycondensation of silylated 4-tert-butylcatechol and 4,4?-difluorodiphenylsulfone in N-methylpyrrolidone. The feed ratio and the reaction time were varied to study the influence of stoichiometry and conversion on molecular weight and extent of cyclization. Molecular weights and molecular weight distributions (MWD)s were characterized by SEC measurements calibrated with polystyrene. Light scattering confirmed that calibration with polystyrene gives reasonable results and revealed a tendency towards a bimodal MWD for the samples rich in cycles. The MALDI-TOF mass spectrometry indicated that the extent of cyclization increased with higher conversion and with optimization of the stoichiometry. This interpretation was confirmed by 1H NMR endgroup analyses. For the samples with the highest molar masses only mass peaks of cycles were found, which were detectable up to 20 000 Da before and up to 27 000 Da after fractionation. Via the pseudo-high dilution method low molar mass poly(ether sulfone) containing more than 95 mol% of cycles were prepared, and even these low molar mass samples had broad MWDs. DSC measurements indicated that the glass transition temperatures depend on the structure of the endgroups and increase with higher fractions of cycles. KW - Poly(ether sulfone)s KW - Polycondensation KW - MALDI-TOF mass spectrometry PY - 2003 DO - https://doi.org/10.1016/S0032-3861(03)00410-5 SN - 0032-3861 SN - 1873-2291 VL - 44 SP - 4471 EP - 4480 PB - Springer CY - Berlin AN - OPUS4-2623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Vakhtangishvili, L. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter T1 - Cyclic Hyperbranched Poly(ether ketone)s Derived from 3,5-Bis(4-fluorobenzoyl)phenol N2 - 3,5-Bis(4-fluorobenzoyl)phenol was polycondensed under various reaction conditions. Low molecular weights were obtained (Mn < 8000 Da), and MALDI-TOF mass spectrometry indicated that the chain growth was limited by cyclization. In the best mass spectra the cyclic, hyperbranched poly(ether ketone)s were detectable up to masses around 14 000 Da. When 4,4'-difluordiphenyl sulfone was added, star-shaped polymers having a diphenyl sulfone star center were formed, but cyclization was not completely suppressed. The results were compared to those obtained from "linear polycondensations" based on 4,4'-difluorobenzophenone (DFBP) and 4-tert-butylcatechol or bisphenol A. The poly(ether ketone)s of DFBP had also low molecular weights and contained high fractions of cycles. It is concluded that also in the case of hyperbranched polymers cyclization competes with propagation at any stage of the polycondensation at any concentration. Therefore, the fundamental trend of any "abn" polycondensation is the formation of star-shaped polymers having a cyclic core and hyperbranched star arms. PY - 2003 DO - https://doi.org/10.1021/ma021799x SN - 0024-9297 SN - 1520-5835 VL - 36 SP - 5551 EP - 5558 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Viala, S. A1 - Tauer, K. A1 - Antonietti, M. A1 - Krüger, Ralph-Peter A1 - Bremser, W. T1 - Structural control in radical polymerization with 1,1-diphenylethylene. 1. Copolymerization of 1,1-diphenylethylene with methyl methacrylate N2 - The role of 1,1-diphenylethylene (DPE) in radical emulsion polymerization of methyl methacrylate is investigated. The presence of DPE causes a strong decrease in both the rate of polymerization and the molecular weight. According to the results of structure analysis by means of MALDI-TOF mass spectrometry, UV–vis spectroscopy, and 1H–NMR spectroscopy, DPE is incorporated in the copolymer chain exclusively as a reactive recombinant ?,p-dimer, underlining the peculiar role of DPE in radical polymerizations. KW - Emulsion polymerization KW - 1,1-Diphenylethylene KW - Copolymer structure PY - 2002 DO - https://doi.org/10.1016/S0032-3861(02)00676-6 SN - 0032-3861 SN - 1873-2291 VL - 43 IS - 26 SP - 7231 EP - 7241 PB - Springer CY - Berlin AN - OPUS4-1919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klapdohr, S. A1 - Moszner, N. A1 - Kickelbick, G. A1 - Krüger, Ralph-Peter T1 - Investigation of the Structure of Polymerizable Silsesquioxanes by GPC and MALDI-TOF-MS in Relation to their Viscosity N2 - Hydrolytic condensation of different methacrylate groups containing alkoxy silanes yielded resins which showed interesting properties as a matrix for dental composites. For this purpose, resins of low viscosity are desired resulting in composites with a high amount of inorganic fillers. Our investigations demonstrated that the viscosity of the obtained polycondensates was predominantly influenced by the kind of organic spacer between the methacrylate group and the silicon atom. In addition, the viscosity also significantly changed in dependence of the kind of structure units built. NMR spectroscopic investigations as well as size exclusion chromatography (SEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry showed that the formed structures depended both on the kind of catalyst used for hydrolysis/condensation and the bulkiness of the organic substituent at the silicon atom. KW - Nanostructure KW - Sols KW - Polycondensation KW - Silicon compounds KW - Dental PY - 2006 DO - https://doi.org/10.1007/s00706-006-0442-z SN - 0026-9247 SN - 1434-4475 VL - 137 SP - 667 EP - 679 PB - Springer CY - Wien AN - OPUS4-12139 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. A1 - Chatti, S. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter T1 - Macrocycles 27 - Cyclic Aliphatic Polyesters of Isosorbide N2 - Numerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo- and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back-biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated ß-cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. KW - Polycondensation KW - Cyclization KW - Isosorbide KW - Polyesters KW - MALDI PY - 2003 DO - https://doi.org/10.1002/pola.10933 SN - 0360-6376 SN - 0887-624X VL - 41 IS - 21 SP - 3414 EP - 3424 PB - Wiley CY - Hoboken, NJ AN - OPUS4-12017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Falkenhagen, Jana A1 - Krüger, Ralph-Peter A1 - Just, Ulrich T1 - Principle of Two-Dimensional Characterization of Copolymers N2 - Two-dimensional polymer characterization is used for a simultaneous analysis of molar masses and chemical heterogeneities (e.g., end groups, copolymer composition, etc.). This principle is based on coupling of two different chromatographic modes. Liquid adsorption chromatography at critical conditions (LACCC) is applied for a separation according to the chemical heterogeneity, whereas in the second-dimension fractions are analyzed with regard to their molar mass distribution by means of size exclusion chromatography (SEC). Because appropriate standards for a calibration of the SEC are seldom available, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was used to substitute the SEC. The LACCC-MALDI MS coupling enables acquiring additional structural information on copolymer composition, which can considerably enhance the performance of this coupled method. KW - MALDI-TOF MS KW - Chromatographie KW - Kopplung PY - 2007 DO - https://doi.org/10.1021/ac062145f SN - 0003-2700 SN - 1520-6882 VL - 79 IS - 13 SP - 4814 EP - 4819 PB - American Chemical Society CY - Washington, DC AN - OPUS4-17722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falkenhagen, Jana A1 - Jancke, Harald A1 - Krüger, Ralph-Peter A1 - Rikowski, Eckhard A1 - Schulz, Günter T1 - Characterization of Silsesquioxanes by Size-exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry N2 - Liquid chromatography in combination with spectroscopic methods like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) or nuclear magnetic resonance (NMR) spectroscopy is a powerful method to characterize silsesquioxanes and silsesquioxane mixtures. As new examples, the formation of silsesquioxyl-substituted silsesquioxanes [(n-octyl)7(SiO1.5)8]2O and [(n-octyl)7(SiO1.5)8O]2[(n-octyl)6(SiO1.5)8] as well as the cage rearrangement of octa-[(n-heptyl)silsesquioxane] to larger structur es [(n-heptyl)SiO1.5)]n up to n=28 are shown. PY - 2003 DO - https://doi.org/10.1002/rcm.911 SN - 0951-4198 SN - 1097-0231 VL - 17 IS - 4 SP - 285 EP - 290 PB - Wiley CY - Chichester AN - OPUS4-2182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falkenhagen, Jana A1 - Friedrich, Jörg Florian A1 - Schulz, Günter A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Weidner, Steffen T1 - Liquid Adsorption Chromatography near Critical Conditions of Adsorption coupled with Matrix-assisted Laser Desorption/Ionization Mass Spectrometry N2 - Chemical heterogeneities and molecular weight distributions of poly(ethylene oxide) (PEO)-co-polymethylene (PM) model oligomers, which are relevant to the synthesis of commonly used tensides, were investigated. For analytical characterization, the well-known principle of liquid adsorption chromatography at 'critical conditions' (LACCC) was modified. Near the critical conditions of adsorption of the PEO unit, e.g., at slight adsorption conditions of PM, the copolymers could be separated according to their PM chain length. The eluates were separated and single fractions of each peak were continuously transferred onto the MALDI target by means of a commercially available device. Simultaneously, the MALDI matrix solution was continuously added with a second pump. This procedure offers the possibility of the formation of homogeneous matrix-polymer textures. By MALDI-MS a complete characterization of the chemical composition (PEO and PM chain length) of each peak could be achieved. The obtained MALDI mass spectra of the eluates at different retention times could be used for the molecular weight calibration of the LAC system. In this way, an additional application of SEC, as in conventional 2D-chromatography, was avoided by using the MALDI method as quasi chromatographic separation KW - Liquid adsorption chromatography KW - Matrix-assisted laser desorption KW - Ionization mass spectrometry KW - Coupling methods KW - MALDI PY - 2000 DO - https://doi.org/10.1080/10236660008034644 SN - 1023-666X SN - 1563-5341 VL - 5 SP - 549 EP - 562 PB - Gordon and Breach Publ. CY - Amsterdam AN - OPUS4-2168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -