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 - 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 - CONF A1 - Krüger, Ralph-Peter T1 - Hyphenated liquid-chromatographic, spectroscopic and spectrometric techniques for polymer characterization T2 - Polymerwerkstoffe 2006 CY - Halle (Saale), Germany DA - 2006-09-27 PY - 2006 AN - OPUS4-13808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Structure and Related Properties of Polymerizable Silsesquioxanes as a Matrix for Dental Composites T2 - 13th International Workshop on Sol-Gel Science and Technology CY - Los Angeles, CA, USA DA - 2005-08-21 PY - 2005 AN - OPUS4-10748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Synthesis and Characterisation of Polyhedral Silsesquioxanes with Nanotubular Structures T2 - DVM-Tagung "Werkstoffprüfung 2005" CY - Berlin, Germany DA - 2005-12-01 PY - 2005 AN - OPUS4-11793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenhagen, Jana A1 - Krüger, Ralph-Peter A1 - Rikowski, Eckhard A1 - Schulz, Günter A1 - Friedrich, Jörg Florian ED - Grellmann, W. T1 - Synthesis and Characterisation of Polyhedral Silsesquioxanes with Nanotubular Structures T2 - 23. DVM-Vortrags- und Diskussionstagung "Werkstoffprüfung 2005", DA - 2005-12-01 PY - 2005 SP - 25 EP - 30 PB - DVM AN - OPUS4-11947 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Charakterisierung biologisch abbaubarer Homo- und Copolyester T2 - 19. Suttgarter Kunststoff-Kolloquium CY - Stuttgart, Germany DA - 2005-03-09 PY - 2005 AN - OPUS4-7127 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Ralph-Peter A1 - Heinemann, M. A1 - Falkenhagen, Jana A1 - Hartmann, A. A1 - Friedrich, Jörg Florian A1 - Fritz, H.-G. ED - Fritz, H. ED - Eisenbach, C. T1 - Charakterisierung biologisch abbaubarer Homo- und Copolyester / Characterisation of biodegradable Homo- and Copolyesters T2 - 19. Stuttgarter Kunststoff-Kolloquium 2005 CY - Stuttgart, Deutschland DA - 2005-03-09 KW - MALDI-TOF-MS KW - Bioabbaubare Polyester KW - Flüssigchromatographie KW - Methodenkopplung KW - Biodegradable polyesters KW - Liquid chromatography KW - Coupling of analytical methods PY - 2005 SN - 3-00-015246-6 SP - 5/P1-1 - 5/P1-9 PB - IKT CY - Stuttgart AN - OPUS4-11767 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Fortschritte bei der Polylactid-Characterisierung T2 - 9. Kolloquium "MALDI-TOF-MS und synthetische Polymere", BAM CY - Berlin, Germany DA - 2005-05-10 PY - 2005 AN - OPUS4-11555 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Characterization of Polyesters and Copolyesters by Coupled Liquid Chromatographic and Spectroscopic Techniques T2 - 11. Internationale Fachtagung Polymerwerkstoffe 2004 CY - Halle (Saale), Germany DA - 2004-09-29 PY - 2004 AN - OPUS4-4339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Ralph-Peter T1 - Book review: H. Pasch and W. Schrepp "MALDI-TOF Mass Spectrometry of Synthetic Polymers" PY - 2004 DO - https://doi.org/10.1002/macp.200400155 SN - 1022-1352 SN - 1521-3935 VL - 205 SP - 1284 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-3567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Influence of L-Lactide Acidity on the Synthesis of Poly(L-Lactide) by Reactive Extrusion and Special Combined Analytical Concepts for the Characterization of Polylyctides T2 - International Union of Pure and Applied Chemistry (IUPAC), Macro 2004 CY - Paris, France DA - 2004-07-04 PY - 2004 AN - OPUS4-3538 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Fortschritte bei der Polylactidcharacterisierung T2 - Fachgruppenvollversammlung VI.3, BAM CY - Berlin, Germany DA - 2004-12-14 PY - 2004 AN - OPUS4-5536 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Zur Charakterisierung von bioabbaubaren Polyestern durch Kopplung von chromatographischen Methoden mit der MALDI-Flugzeitmassenspektrometrie T2 - 11. Internationale Fachtagung Polymerwerkstoffe 2004 CY - Halle (Saale), Germany DA - 2004-09-29 PY - 2004 AN - OPUS4-5158 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Zur Charakerisierung von bioabbaubaren Polyestern durch Kopplung von chromatographischen Methoden mit der MALDI-Flugzeitmassenspektrometrie T2 - Polydays 2004 CY - Potsdam, Germany DA - 2004-10-04 PY - 2004 AN - OPUS4-5172 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Zur Synthese und Charakterisierung von Polylactiden T2 - Analytica Conference 2004 CY - Munich, Germany DA - 2004-05-11 PY - 2004 AN - OPUS4-3539 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Zur Chracterisierung von bioabbaubaren Polyestern durch Kopplung von chromatographischen Methoden mit der MALDI-Flugzeitmassenspektrometrie T2 - 11. Internationale Fachtagung Polymerwerkstoffe 2004 CY - Halle (Saale), Germany DA - 2004-09-29 PY - 2004 AN - OPUS4-3540 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter A1 - Falkenhagen, Jana T1 - Characterization of Polyesters and Copolyesters by Coupled Liquid Chromatographic and Spectroscopic Techniques T2 - Polydays 2004 CY - Potsdam, Germany DA - 2004-10-04 PY - 2004 AN - OPUS4-4341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter T1 - Zur Synthese und Characterisierung von Polylactiden T2 - Analytica Conference 2004 CY - Munich, Germany DA - 2004-05-11 PY - 2004 AN - OPUS4-5096 LA - deu 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 -