TY - JOUR A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Schulz, Günter A1 - Rikowski, E. T1 - Zur Charakterisierung von Si-Polymeren durch flüssigchromatographische Verfahren in Kopplung mit der MALDI-TOF-MS N2 - Summary. The coupling of the three liquid chromatographic modes with MALDI-TOF mass spectrometry is suitable for the determination of the molecular, functional, and chemical heterogeneities of Si polymers. Silsesquioxanes and siloxanes serve as examples for this method of structure identification. The substance specific construction of the SEC calibration curve by means of MALDI-MS is shown. Zusammenfassung. Die Kopplung der drei flüssigchromatographischen Modi mit MALDI-TOF-Massenspektrometrie ist zur Bestimmung der molekularen, funktionalen und chemischen Verteilungen von Si-Polymeren geeignet. Silsesquioxane und Siloxane dienen als Beispiele für diese Art der Strukturerkennung. Die substanzspezifische Konstruktion einer SEC-Eichkurve mit Hilfe der MALDI-MS wird gezeigt. KW - Si polymer characterization KW - LC/MALDI-TOF-MS PY - 1999 DO - https://doi.org/10.1007/PL00010162 SN - 0026-9247 SN - 1434-4475 VL - 130 IS - 1 SP - 163 EP - 174 PB - Springer CY - Wien AN - OPUS4-2163 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Eggerstedt, S. A1 - Krüger, Ralph-Peter T1 - Macrocycles, 6a / MALDI-TOF mass spectrometry of tin-initiated macrocyclic polylactones in comparison to classical mass-spectroscopic methods PY - 1999 SN - 1022-1352 SN - 1521-3935 VL - 200 IS - 6 SP - 1284 EP - 1291 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. A1 - Hauser, K. A1 - Krüger, Ralph-Peter A1 - Schulz, Günter T1 - Macrocycles 12. Ring-Opening Polycondensations of Tin-Containing Macrocycles with Bis(Thioarylester)s N2 - 2,2-Dibutyl-2-stanna-1,3-dioxepane (DSDOP) was polycondensed with bis(4-chlorothiophenyl) suberat under various reaction conditions, but only moderate molecular weights (Mn 10000) were obtained. The MALDI-TOF mass spectrosmetry revealed the formation of cyclic oligo- and polyesters in addition to linear species having OH, CO2H, and unreacted 4-chlorothiophenyl ester endgroups. Furthermore, -Caprolactone (-CL) was polymerized with DSDOP as the initiator at monomer/initiator (M/I) ratios of 20 and 50. The resulting tin-containing macrocyclic polylactones were reacted with sebacic acid bis(4-thiocresyl)ester at three different temperatures and with different reaction times. Analogous polycondensations were conducted with suberic acid bis(4-chlorothiophenyl) ester. The presence of thioarylester endgroups in the isolated polyesters was checked by 1H NMR spectroscopy. The highest conversions were found at long reaction times (24 or 72 hours), or after the addition of pyridine and N,N-dimethylaminopyridine as catalysts. Despite high conversions, the number average molecular weights (Mn's) did not exceed values around 20000. Even in the samples having the highest molecular weights, unreacted 4-chlorothiophenylester endgroups were detected by GPC measurements evaluated with a UV-detector. It is concluded that both factors, cyclization and incomplete conversion, contribute to the limitation of the chain growth. KW - Ring-Opening Polycondensations KW - Macrocycles KW - Polyesters PY - 2000 DO - https://doi.org/10.1081/MA-100101099 SN - 1060-1325 SN - 1520-5738 VL - 37 IS - 4 SP - 379 EP - 394 PB - Taylor & Francis CY - Philadelphia, PA AN - OPUS4-2167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 - 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 - Veith, M. A1 - Elsässer, R. A1 - Krüger, Ralph-Peter T1 - Synthesis of Dendrimers with a N-Si-C Framework N2 - A novel family of air-stable dendrimers with a N-Si-C framework has been prepared up to the fourth generation. The divergent synthesis starts with the hydrosilylation of the trisilazane N(SiMe2vinyl)3 [0-G(vinyl)] by HSiMe2Cl, which gives the three-directional core molecule N(SiMe2CH2CH2SiMe2Cl)3 [0-G(Cl)]. A 1-to-2 branching achieved by reacting the core molecule [0-G(Cl)] with 3 equiv of KN(SiMe2vinyl)2 affords the first generation dendrimer [1-G(vinyl)]. By repeating the above two steps, the second [2-G(vinyl)], third [3-G(vinyl)], and fourth generation [4-G(vinyl)] can be obtained. The compounds have been characterized by 1H, 13C, and 29Si NMR spectroscopy, by elemental analysis, and up to the third generation by MALDI-TOF mass spectrometry. Gel permeation chromatography was used to prove the fourth generation [4-G(vinyl)]. PY - 1999 DO - https://doi.org/10.1021/om9807708 SN - 0276-7333 SN - 1520-6041 VL - 18 IS - 4 SP - 656 EP - 661 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2162 LA - eng 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 -