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Anionic Copolymerization (anionic + copolymerization)
Selected AbstractsKinetics Approximation Considering Different Reactivities of the Structural Units Formed by the Anionic Copolymerization of 1,3-Butadiene and Styrene Using Al/Li/Ba as InitiatorMACROMOLECULAR REACTION ENGINEERING, Issue 8 2009José. A. Tenorio López Abstract The copolymerization reaction of butadiene and styrene copolymers prepared by anionic living polymerization using an initiator composed of alkyl aluminum, n -butyl lithium, and barium alkoxide is studied using a kinetic model that considers the reactivity of active sites to be different; this assumption is justified by the varying geometric configurations. With the first-order Markov model, the expressions for the fraction of active sites and dyad distribution are obtained. The rate constants are determined by fitting to the conversion and Bernoulli dyad data using the nonlinear least squares method. The conversion and dyad sequence distribution are correctly predicted, and the experimental results indicate that the microstructure and sequence distribution do not change with the conversion and temperature. [source] Stereocontrolled anionic alternating copolymerization of ethylphenylketene with benzaldehyde by a bisoxazoline ligandJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2004Daisuke Nagai Abstract Anionic copolymerization of ethylphenylketene with benzaldehyde with butyllithium or diethylzinc as the initiator proceeded in a perfect 1:1 alternating manner to produce the corresponding polyester, whose repeating unit had two adjacent chiral centers. The relative stereochemistry between these two chiral centers was successfully controlled by the addition of (S,S)-(-)-2,2,-isopropylidenebis(4- tert -butyl-2-oxazoline), producing the corresponding polyester that had excellent diastereoselectivity (erythro -configuration : threo -configuration = 4:96). The diastereomeric ratio was determined by high-performance liquid chromatography analysis of the diol, which was obtained by reductive degradation of the polyester while maintaining the configuration of the repeating unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5384,5388, 2004 [source] Anionic copolymerization of hexanelactam with functionalized polyisopreneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2003R. Mateva Abstract Block copolymers of the A-B-C-B-A type were synthesized for the first time via the activated anionic polymerization of hexanelactam (HL) with Na-HL as an initiator and macroactivators [or polymeric activators (PACs)] as elastificators for nylon-6. The PACs were prepared by the functionalization of telechelic hydroxyl-terminated poly(ethylene oxide),polyisoprene,poly(ethylene oxide) copolymers with different diisocyanates. Hexamethylene diisocyanate (1,6-diisocyanatohexane) and isophorone diisocyanate (5-isocyanate1-isocyanatomethyl-1,3,3-trimetylcyclohexane) were used as functionalizing agents. This article reports on the effects that the various central elastomeric PAC blocks (type, content, and molecular weight) had on the polymerization kinetics and on the structure and molecular weights of the multiblock copolymers obtained. The copolymers were characterized spectroscopically. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 487,496, 2003 [source] Anionic alternating copolymerization of 3,4-dihydrocoumarin and glycidyl ethers: A new approach to polyester synthesisJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2008Kazuya Uenishi Abstract Anionic copolymerizations of 3,4-dihydrocoumarin (DHCM) and a series of glycidyl ethers (n -butyl glycidyl ether, tert -butyl glycidyl ether, and allyl glycidyl ether) with 2-ethyl-4-methylimidazole as an initiator proceeded in a 1:1 alternating manner to give the corresponding polyesters, whose structures were confirmed by spectroscopic analyses and reductive scission of the ester bonds in the main chain with lithium aluminum hydride, followed by detailed analyses of the resulting fragments. The polyester obtained by the copolymerization of DHCM and allyl glycidyl ether inherited the allyl groups in the side chain, whose applicability to chemical modifications of the polyester was successfully demonstrated by a platinum-catalyzed hydrosilylation reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4092,4102, 2008 [source] Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry study on copolymers obtained by the alternating copolymerization of bis(,-lactone) and epoxide with potassium tert -butoxideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2005Chenxi Zhang Abstract Oligomer samples obtained by the anionic copolymerization of a bis(,-lactone), 2,8-dioxa-1-methylbicyclo[3.3.0]octane-3,7-dione (1), and glycidyl phenyl ether with potassium tert -butoxide have been analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The MALDI-TOF mass spectra of these cooligomers show well-resolved signals that can be reliably assigned to linear, alternating cooligomers that have carboxylate chain ends or alkoxide chain ends and cyclic ones. The formation of these three series of cooligomers suggests that the polymerization process involves concomitant intermolecular transesterification and intramolecular back-biting. The intramolecular back-biting reaction causes the formation of cyclic cooligomers, whereas the intermolecular transesterification causes the reduction of the molecular weight and the transformation of the alkoxide active chain end into a carboxylate chain end. The MALDI-TOF mass spectrometry study has shown that an excess of monomer 1 enhances the selectivity of propagation by increasing the probability of the attack of the alkoxide chain end to 1. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2643,2649, 2005 [source] | ||||||||||