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Random Copolymerization (random + copolymerization)
Selected AbstractsCopolymerization of cyclopentadiene with styrene by methylaluminoxane catalyst,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7-8 2006Junxian Hou Abstract Random copolymerization of cyclopentadiene (CPD) and styrene initiated by methylaluminoxane was investigated. The copolymer was analyzed using FT-IR, 1H-NMR and differential scanning calorimetry (DSC). The reactivity ratios of the monomers were rCPD,=,19.53, rstyrene,=,0.60. A single glass transition temperature is observed for each copolymer, which is in agreement with a random type copolymer structure. And a cationic initiation mechanism was speculated based on the polymerization results. Copyright © 2006 John Wiley & Sons, Ltd. [source] Block copolymerizations of higher 1-olefins with traditional polar monomers using metallocene-type single component lanthanide initiatorsPOLYMER INTERNATIONAL, Issue 8 2004Hajime Yasuda Abstract Block copolymerizations of 1-pentene or 1-hexene with methyl methacrylate or ,-caprolactone were explored using [Me2Si(2-SiMe3 -4- t -BuMe2SiC5H2)2YH]2 (1) or [Me2Si(2-SiMe3 -4- t -BuC5H2)2SmH]2 (2) as an initiator in toluene or in neat mixtures by the successive additions of monomers in this order. Random copolymerizations of 1-pentene with 1-hexene, and random copolymerization of ethylene with 1-hexene were also performed using 1 as an initiator. Copyright © 2004 Society of Chemical Industry [source] Thermoresponsive brush copolymers with poly(propylene oxide- ran -ethylene oxide) side chains via metal-free anionic polymerization "grafting from" techniqueJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2010Junpeng Zhao Abstract Thermoresponsive brush copolymers with poly(propylene oxide- ran -ethylene oxide) side chains were synthesized via a "grafting from" technique. Poly(p -hydroxystyrene) was used as the backbone, and the brush copolymers were prepared by random copolymerization of mixtures of oxyalkylene monomers, using metal-free anionic ring-opening polymerization, with the phosphazene base (t -BuP4) being the polymerization promoter. By controlling the monomer feed ratios in the graft copolymerization, two samples with the same side-chain length and different compositions were prepared, both of which possessed high molecular weights and low molecular weight distributions. The results from light scattering and fluorescence spectroscopy indicated that the brush copolymers in their dilute aqueous solutions were near completely solvated at low temperature and underwent slight intramolecular chain contraction/association and much more profound intermolecular aggregation at different stages of the step-by-step heating process. Above 50 °C, very turbid solutions, followed by macrophase separation, were observed for both of the samples, which implied that it was difficult for the brush copolymers to form stable nanoscopic aggregates at high temperature. All these observations were attributed, at least partly, to the distribution of the oxyalkylene monomers along the side chains and the overall brush-like molecular architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2320,2328, 2010 [source] Copolymerization of amino acid and amino ester functionalized norbornenes via living ring-opening metathesis polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2008Stefano C. G. Biagini Abstract The block and random copolymerization of a series of amino acid and amino ester functionalized norbornenes by ring-opening metathesis polymerization (ROMP) induced by the well-defined molybdenum [Mo(N -2,6- iPrC6H3)(CHCMe2)Ph)(OCMe3)2] or ruthenium [Ru(PCy)2Cl2(CHPh)] based initiators is described. The monomers are derived from the amino acids glycine, alanine, and isoleucine or the methyl esters of these amino acids and either endo- or exo- norborn-5-ene-2,3-dicarboxylic anhydride. Enantiomerically pure monomers afforded optically active polymers, and the mechanism and kinetics of the copolymerizations are investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7985,7995, 2008 [source] Atom transfer radical polymerization of n -butyl acrylate catalyzed by CuBr/N -(n -hexyl)-2-pyridylmethanimineJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002Huiqi Zhang Abstract The homogeneous atom transfer radical polymerization (ATRP) of n -butyl acrylate with CuBr/N -(n -hexyl)-2-pyridylmethanimine as a catalyst and ethyl 2-bromoisobutyrate as an initiator was investigated. The kinetic plots of ln([M]0/[M]) versus the reaction time for the ATRP systems in different solvents such as toluene, anisole, N,N -dimethylformamide, and 1-butanol were linear throughout the reactions, and the experimental molecular weights increased linearly with increasing monomer conversion and were very close to the theoretical values. These, together with the relatively narrow molecular weight distributions (polydispersity index , 1.40 in most cases with monomer conversion > 50%), indicated that the polymerization was living and controlled. Toluene appeared to be the best solvent for the studied ATRP system in terms of the polymerization rate and molecular weight distribution among the solvents used. The polymerization showed zero order with respect to both the initiator and the catalyst, probably because of the presence of a self-regulation process at the beginning of the reaction. The reaction temperature had a positive effect on the polymerization rate, and the optimum reaction temperature was found to be 100 °C. An apparent enthalpy of activation of 81.2 kJ/mol was determined for the ATRP of n -butyl acrylate, corresponding to an enthalpy of equilibrium of 63.6 kJ/mol. An apparent enthalpy of activation of 52.8 kJ/mol was also obtained for the ATRP of methyl methacrylate under similar reaction conditions. Moreover, the CuBr/N -(n -hexyl)-2-pyridylmethanimine-based system was proven to be applicable to living block copolymerization and living random copolymerization of n -butyl acrylate with methyl methacrylate. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3549,3561, 2002 [source] Synthesis of star-shaped copolymers with methyl methacrylate and n -butyl methacrylate by metal-catalyzed living radical polymerization: Block and random copolymer arms and microgel cores,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2002Kyung-Youl Baek Abstract Various star-shaped copolymers of methyl methacrylate (MMA) and n -butyl methacrylate (nBMA) were synthesized in one pot with RuCl2(PPh3)3 -catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB- or BA-type block copolymer arms with controlled lengths and comonomer compositions in high yields (,90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 633,641, 2002; DOI 10.1002/pola.10145 [source] Synthesis of Random Copolymers Poly (methylmethacrylate- co -azo monomer) by ATRP-AGETMACROMOLECULAR SYMPOSIA, Issue 1 2009M.A. Nájera Abstract The synthesis of the azo molecule 1-(2-(4-nitrophenyl) diazenyl) naphtalen-2-ol which has been functionalized with a methacryloxyl fraction is now reported. This azo monomer was copolymerized with methyl methacrylate (MMA) by ATRP where the active species is prepared "in situ" after the reduction reaction of the metal complex Cu (II) - HMTETA by tin 2-ethylhexanoate in 2-butanone as solvent. Experimental conditions for the controlled homopolymerization of MMA were established. By adjusting the amount of reducing agent, a good correlation between theoretical and experimental molecular weight was obtained. Such conditions were also employed for the random copolymerization of MMA with the synthesized azo monomer. [source] Block copolymerizations of higher 1-olefins with traditional polar monomers using metallocene-type single component lanthanide initiatorsPOLYMER INTERNATIONAL, Issue 8 2004Hajime Yasuda Abstract Block copolymerizations of 1-pentene or 1-hexene with methyl methacrylate or ,-caprolactone were explored using [Me2Si(2-SiMe3 -4- t -BuMe2SiC5H2)2YH]2 (1) or [Me2Si(2-SiMe3 -4- t -BuC5H2)2SmH]2 (2) as an initiator in toluene or in neat mixtures by the successive additions of monomers in this order. Random copolymerizations of 1-pentene with 1-hexene, and random copolymerization of ethylene with 1-hexene were also performed using 1 as an initiator. Copyright © 2004 Society of Chemical Industry [source] Homopolymerizations and random copolymerizations of olefins with amino-substituted cyclopentadienylchromium complexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2002Keiji Ogata Abstract 1-(2- N,N -Dimethylaminoethyl)-2,3,4,5-tetramethylcyclopentadienyl-chromium dichloride (1), (2- N,N -dimethylaminoethyl)cyclopentadienylchromium dichloride (6), and (2- N,N -dimethylaminoethyl)indenylchromium dichloride (7) in the presence of modified methylaluminoxane exhibit high catalytic activities for the polymerization of ethylene with random copolymerizations of ethylene with propylene, ethylene with 1-hexene, and propylene with 1-hexene. These initiators conduct polymerizations to give high molecular weight polymers with low polydispersities. However, the stereoregularities are very poor in these reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2759,2771, 2002 [source] Feasible compositions for random copolymerizations,POLYMER ENGINEERING & SCIENCE, Issue 2 2001Raymond L. Smith Using the attainable region approach, feasible compositions and conversions for random copolymers are determined, along with altermatives for the related reactor configurations. This analysis attempts to find all of the possible compositions that can be produced by any system of reactros and mixing. The average copolymer compositions are bounded by the feed composition and the instantaneous copolymer composition produced at the initial conditions. Since the instantaneous copolymer composition can be found through the Mayo-Lewis equation, that case and the feed composition mark the limiting feasible compositions. The results can also be used to determine the range of feed compositions for which a specific copolymer product composition is possible. If the addition of monomer at any point in the reactor system is possible, e.g., by side-feeding, the analysis indicates that any desired copolymer composition can be obtained. [source] | ||||||||||