TY - JOUR A1 - Shaik, A.-A. A1 - Richter, M. A1 - Kricheldorf, H. A1 - Krüger, Ralph-Peter T1 - New polymer syntheses - CIX. Biodegradable, alternating copolyesters of terephthalic acid, aliphatic dicarboxylic acids, and alkane diols JF - Journal of polymer science A, polymer chemistry N2 - Copolyesters with an alternating sequence of terephthalic acid and aliphatic dicarboxylic acids were prepared with three different methods. First, dicarboxylic acid dichlorides were reacted with bis(2-hydroxyethyl)terephthalate (BHET) in refluxing 1,2-dichlorobenzene. Second, the same monomers were polycondensed at 0-20 °C in the presence of pyridine. Third, dicarboxylic acid dichlorides and silylated BHET were polycondensed in bulk. Only this third method gave satisfactory molecular weights. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the copolyesters prepared by the pyridine and silyl methods might have contained considerable fractions of cyclic oligoesters and polyesters despite the absence of transesterification and backbiting processes. The alternating sequences and thermal properties were characterized with 1H NMR spectroscopy and differential scanning calorimetry measurements, respectively. In agreement with the alternating sequence, all copolyesters proved to be crystalline, but the crystallization was extremely slow [slower than that of poly(ethylene terephthalate)]. A second series of alternating copolyesters was prepared by the polycondensation of silylated bis(4-hydroxybut- yl)terephthalate with various aliphatic dicarboxylic acid dichlorides. The resulting copolyesters showed significantly higher rates of crystallization, and the melting temperatures were higher than those of the BHET-based copolyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3371-3382, 2001 KW - Poly(ethylene terephthalate) KW - Poly(butylene terephthalate) KW - Alternating sequence KW - Macrocycles KW - Crystallization KW - Biodegradable polyesters PY - 2001 DO - https://doi.org/10.1002/pola.1320 SN - 0360-6376 SN - 0887-624X VL - 39 IS - 19 SP - 3371 EP - 3382 PB - Wiley CY - Hoboken, NJ AN - OPUS4-2173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bünger, H. A1 - Krüger, Ralph-Peter A1 - Pietschmann, S. A1 - Wüstneck, N. A1 - Kaufner, L. A1 - Tschiersch, R. A1 - Pison, U. T1 - Two hydrophobic protein fractions of ovine pulmonary surfactant: Isolation, characterisation and biophysical activity JF - Protein expression and purification N2 - Pulmonary surfactant contains two extremely hydrophobic proteins, SP-B and SP-C. We present a novel HPLC method for the preparation of these hydrophobic proteins. It is based on size-exclusion chromatography using the apolar stationary-phase butyl silica gel and isocratic elution with acidified chloroform/methanol. Samples for HPLC were prepared from sheep lung lavage fluid by centrifugation and extraction with chloroform/methanol. Amino acid analyses of the two protein fractions revealed sequences that are consistent with SP-B and SP-C, respectively. MALDI-TOF-MS analyses of the SP-B fraction showed one major peak of dimeric SP-B with m/z 17,361, and additional peaks of monomeric and oligomeric forms, which are predominantly even numbered. The SP-C fraction showed a peak at m/z 4200, consistent with the theoretical mass of the dipalmitoylated form of this protein. The biophysical activity of pure sheep SP-B and SP-C was evaluated by measuring the surface tension using axisymmetric drop shape analysis for captive bubbles. We found distinct surface pressure versus surface area isotherms of SP-B and SP-C indicating different biophysical activities for these surfactant proteins. The new preparative HPLC method is able to replace the established, time-consuming low-pressure liquid chromatography method for the isolation of SP-B and SP-C from lipids. KW - Surfactant proteins KW - SP-B KW - SP-C KW - Preparative HPLC KW - MALDI-TOF-MS KW - Surface pressure KW - Captive bubble PY - 2001 DO - https://doi.org/10.1006/prep.2001.1510 SN - 1046-5928 SN - 1096-0279 VL - 23 IS - 2 SP - 319 EP - 327 PB - Elsevier CY - Amsterdam AN - OPUS4-2174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Czichocki, G. A1 - Heger, R. A1 - Much, Helmut A1 - Krüger, Ralph-Peter A1 - Goedel, W.A. T1 - Synthesis of Polyisoprenes with Sulfonate Head Groups and their Purification by HPLC JF - Tenside, surfactants, detergents PY - 2001 SN - 0932-3414 SN - 0040-3490 VL - 38 IS - 3 SP - 168 EP - 172 PB - Hanser CY - München AN - OPUS4-2175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Böhme, S. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter A1 - Schulz, Günter T1 - Macrocycles 18. The Role of Cyclization in Syntheses of Poly(ether-sulfone)s JF - Macromolecules N2 - Poly(ether-sulfone)s having an identical backbone were prepared by four different methods. First, silylated bisphenol A (BSBA) was polycondensed with 4,4'-difluorodiphenyl sulfone (DFDPS) and K2CO3 in N-methylpyrrolidone with variation of the temperature. Second, analogous polycondensation were conducted using CsF as catalyst (and no K2CO3). Third, CsF-catalyzed polycondensations BSBA and DFDPS were conducted in bulk up to 290 C. Fourth, free bisphenol was polycondensed with DFDPS or 4,4'-dichlorodiphenyl sulfone and K2CO3 in DMSO with azeotropic removal of water. MALDI-TOF mass spectroscopy revealed that the first method mainly yielded cyclic poly(ether-sulfone)s which were detected up to masses around 13 000 Da. These and other results suggest that these polycondensations take a kinetically kontrolled course at tempeatures 145 C. This interpretation is also valid for the fourth method where high yields of cycles were obtained with DFDPS. With the less reactive 4,4'-dichlorodiphenyl sulfone lower conversions, lower molecular weights and lower fractions of cycles were found. In contrast to KF (resulting from K2CO3) CsF cleaves the poly(ether sulfone) backbone at temperatures > 145 C. Smaller amounts of smaller cycles were found in these CsF-catalyzed polycondensations which were in this case the result of thermodynamically controlled "back-biting degradation". PY - 2001 DO - https://doi.org/10.1021/ma010218l SN - 0024-9297 SN - 1520-5835 VL - 34 SP - 8886 EP - 8893 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Ralph-Peter A1 - Falkenhagen, Jana A1 - Schulz, Günter A1 - Gloede, J. T1 - Charakterisierung von Calixarenen durch Kopplung von Flüssigchromatographie und MALDI-TOF-MS JF - GIT : Labor-Fachzeitschrift KW - Flüssigchromatographie KW - Kopplung LACCC KW - MALDI-TOF-MS KW - Calixarene KW - Novolake PY - 2001 SN - 0016-3538 VL - 45 IS - 4 SP - 380 EP - 384 PB - GIT-Verlag CY - Darmstadt AN - OPUS4-2177 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Rabenstein, M. A1 - Langanke, D. A1 - Schwarz, G. A1 - Schmidt, M. A1 - Maskos, M. A1 - Krüger, Ralph-Peter T1 - Ring-closing polycondensations JF - High performance polymers N2 - The role of cyclization in polycondensations is discussed for two different scenarios: thermodynamically-controlled polycondensation (TCPs) on the one hand and kinetically-controlled polycondensations (KCPs) on the other. The classical Carothers–Flory theory of step-growth polymerization does not include cyclization reactions. However, TCPs involve the formation of cycles via ‘back-biting degradation’, and when the ring–chain equilibrium is on the side of the cycles the main reaction products of the TCP will be cyclic oligomers. Two groups of examples are discussed: polycondensations of salicyclic acid derivatives (e.g. aspirin) and polycondensations of dibutyltin derivatives with long {alpha}-, {omega}-diols or dicarboxylic acids. Furthermore, various kinetically-controlled syntheses of polyesters and polyamides were studied and carefully optimized in the direction of high molecular weights. High fractions of cyclic oligomers and polymers were found by MALDI-TOF mass spectrometry, and their fractions increased with optimization of the process for molecular weight. These results disagree with the Carothers–Flory theory but agree with the theoretical background of the Ruggli–Ziegler dilution method (RZDM). When poly(ether-sulfone)s were prepared from 4,4'-difluorodiphenylsulfone and silylated bisphenol-A two different scenarios were found. With CsF as catalyst at a temperature of more than 145°C cyclic oligoethers were formed under thermodynamic control. When the polycondensation was promoted with K2CO3 in N-methylpyrolidone at ?145°C the formation of cyclic oligoethers and polyethers occurred under kinetic control. A new mathematical formula is presented correlating the average degree of polymerization with the conversion and taking into account the competition between cyclization and propagation. PY - 2001 DO - https://doi.org/10.1088/0954-0083/13/2/312 SN - 0954-0083 SN - 1361-6412 VL - 13 SP - S123 EP - S136 PB - Sage Publ. CY - London AN - OPUS4-2178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Janiak, Ch. A1 - Lange, K.C.H. A1 - Marquardt, P. A1 - Krüger, Ralph-Peter A1 - Hanselmann, R. ED - Sun, J. ED - Janiak, C. T1 - Propene and 1-hexene oligomerization with unbridged alkyl-substituted cyclopentadienyl- and phospholyl-zirconium/MAO catalysts - mechanistic implications from oligomer analyses by NMR, SEC, and MALDI-TOF MS T2 - Advances on organometallic catalysts and olefin polymerization in China and Germany PY - 2001 SP - 117 EP - 142 PB - Chemical Industry Press CY - Bejing AN - OPUS4-2193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter A1 - Falkenhagen, Jana A1 - Much, Helmut A1 - Schulz, Günter A1 - Friedrich, Jörg F. T1 - Beiträge zur Charakterisierung von synthetischen Si-Polymeren durch Kopplung von HPLC-Trennmethoden mit der MALDI-TOF-MS T2 - InCom´01 T2 - InCom´01 CY - Düsseldorf, Germany DA - 2001-03-27 PY - 2001 AN - OPUS4-3351 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter A1 - Falkenhagen, Jana A1 - Much, Helmut A1 - Schulz, Günter A1 - Friedrich, Jörg Florian T1 - Beiträge zur Charakterisierung von synthetischen Si-Polymeren durch Kopplung von HPLC-Trennmethoden mit der MALDI-TOF-MS T2 - InCom 2001 T2 - Incom 2001 - International Symposium on Instrumentalized Analytical Chemistry and Computer Technology CY - Düsseldorf, Deutschland DA - 2001-03-27 PY - 2001 AN - OPUS4-2254 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenhagen, Jana A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Schulz, Günter T1 - Characterization and identification of new polymer structures by optimization and coupling of HPLC and MALDI-TOF-MS T2 - Tagungsband der DECHEMA-Diskussionstagung "Neue Methoden der Polymeranalytik" 2001 T2 - Dechema-Diskussionstagung "Neue Methoden der Polymeranalytik" CY - Mainz, Germany DA - 2001-04-02 PY - 2001 CY - Mainz AN - OPUS4-2255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -