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Cationic Copolymerization (cationic + copolymerization)
Selected AbstractsCationic copolymerization of ,-caprolactone and L,L -lactide by an activated monomer mechanismJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2006gorzata Ba Abstract The cationic homopolymerization and copolymerization of L,L -lactide and ,-caprolactone in the presence of alcohol have been studied. The rate of homopolymerization of ,-caprolactone is slightly higher than that of L,L -lactide. In the copolymerization, the reverse order of reactivities has been observed, and L,L -lactide is preferentially incorporated into the copolymer. Both the homopolymerization and copolymerization proceed by an activated monomer mechanism, and the molecular weights and dispersities are controlled {number-average degree of polymerization,=,([M]0 , [M]t)/[I]0, where [M]0 is the initial monomer concentration, [M]t is the monomer concentration at time t, and [I]0 is the initial initiator concentration; weight-average molecular weight/number-average molecular weight ,1.1,1.3}. An analysis of 13C NMR spectra of the copolymers indicates that transesterification is slow in comparison with propagation, and the microstructure of the copolymers is governed by the relative reactivity of the comonomers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7071,7081, 2006 [source] Synthesis of copolymer from 1,3,5-trioxane and 1,3-dioxolane catalyzed by Maghnite-H+JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Khadidja Beloufa Abstract Copolymers (polyoxymethylene) were prepared by cationic copolymerization of 1,3,5-trioxane (TOX) with 1,3-dioxolane (DOX) in the presence of Maghnite-H+ (Mag-H+) in solution. Maghnite is a Montmorillonite sheet silicate clay, with exchanged protons to produce Mag-H+. Various techniques, including 1H-NMR, 13C-NMR, FT-IR spectroscopy, and Ubbelohde viscometer were used to elucidate structural characteristics properties of the resulting copolymers. The influence of the amount of catalyst, of dioxolane (DOX), temperature, solvent, and time of copolymerization on yield and on intrinsic viscosity of copolymers was studied. The yield of copolymerization depends on the amount of Mag-H+ used and the reaction time. We also propose mechanisms involved in the synthesis of copolymer (polyoxymethylene). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis and crystallization behavior of acetal copolymer/silica nanocomposite by in situ cationic ring-opening copolymerization of trioxane and 1,3-dioxolaneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Lanhui Sun Abstract The acetal copolymer/silica nanocomposite was prepared by in situ bulk cationic copolymerization of trioxane and 1,3-dioxolane in the presence of nanosilica. The crystallization behavior of acetal copolymer/silica nanocomposite was studied by AFM, DSC, XRD, and CPOM, and the macromolecular structure of acetal copolymer/silica nanocomposite was characterized by FTIR and 1H-NMR. The 1H-NMR results showed that the macromolecular chain of acetal copolymer had more than two consecutive 1,3-dioxolane units in an oxymethylene main chain, while that of acetal copolymer/silica nanocomposite had only one 1,3-dioxolane unit in an oxymethylene main chain. There existed interaction between the macromolecular chains and nanoparticles (such as hydrogen bonds and coordination). On one hand, nanoparticles acted as nucleation center, which accelerated the crystallization rate but reduced the crystallinity. The spherulite sizes also decreased with addition of nanoparticles attributed to the nucleation effect. On the other hand, the presence of nanoparticles interrupted the spherical symmetry of the crystallite. In conclusion, the high surface energy and small scale of nanoparticles have a prominent impact on the polymerization mechanism and crystallization behavior of nanocomposite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Living cationic polymerization of amide-functional vinyl ethers: Specific properties of SnCl4 -based initiating systemJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2008Motomasa Yonezumi Abstract Living cationic copolymerization of amide-functional vinyl ethers with isobutyl vinyl ether (IBVE) was achieved using SnCl4 in the presence of ethyl acetate at 0 °C: the number,average molecular weight of the obtained polymers increased in direct proportion to the monomer conversion with relatively low polydispersity, and the amide-functional monomer units were introduced almost quantitatively. To optimize the reaction conditions, cationic polymerization of IBVE in the presence of amide compounds, as a model reaction, was also examined using various Lewis acids in dichloromethane. The combination of SnCl4 and ethyl acetate induced living cationic polymerization of IBVE at 0 °C when an amide compound, whose nitrogen is adjacent to a phenyl group, was used. The versatile performance of SnCl4 especially for achieving living cationic polymerization of various polar functional monomers was demonstrated in this study as well as in our previous studies. Thus, the specific properties of the SnCl4 initiating system are discussed by comparing with the EtxAlCl3,x systems from viewpoints of hard and soft acids and bases principle and computational chemistry. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6129,6141, 2008 [source] New thermosets obtained by the cationic copolymerization of diglycidyl ether of bisphenol A with ,-caprolactone with an improvement in the shrinkage.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2007Abstract Diglycidyl ether of bisphenol A was cured with different proportions of ,-caprolactone with ytterbium triflate as an initiator. The curing was studied by means of differential scanning calorimetry and Fourier transform infrared in the attenuated total reflection mode. The latter was used to monitor the competitive reactive processes and to quantify the conversions of the epoxide, lactone, and intermediate spiroorthoester groups. A partial depolymerization process from the cured material to free ,-caprolactone was also identified. The formation of a stable carbocation and the coordinative capability of ytterbium triflate were the reasons for this unexpected process. The thermal and dynamic mechanical properties of the cured materials were determined with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. An increase in the proportion of ,-caprolactone resulted in an increased curing rate, a decrease in the shrinkage after gelation, and a significant decrease in the glass transition temperature. The introduction of ester linkages into the three-dimensional structure led to more thermally degradable thermosets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1968,1979, 2007 [source] Vibrational spectroscopic investigation of light-induced polymerization process of epoxy resin, polytetrahydrofuran and spirobislactonePOLYMER INTERNATIONAL, Issue 7 2007Yujie Zhang Abstract The light-induced polymerization process of bisphenol F diglycidyl ether (BFDGE), 5,5,-dicarboxylic-7,7,-dioxo-2,2,-spirodi(benzotetrahydrofuran) (DCSBL) and polytetrahydrofuran (pTHF-250) was studied. 4-[(2-Hydroxytetradecyl)oxy]phenyl-phenyliodoniumhexafluoroantimonate, camphorquinone and ethyl 4-dimethylaminobenzoate were used as a photoinitiator system. The polymerization process was induced by light and monitored using Fourier transform infrared spectroscopy. A novel combination-initiation polymerization process was proposed: first, cationic copolymerization of BFDGE and pTHF-250 was initiated by the photoinitiator system and heat was released by this polymerization; then, copolymerization of BFDGE and DCSBL was induced by that heat while pTHF-250 served as an anionic initiator. Copyright © 2007 Society of Chemical Industry [source] New soybean oil-Styrene-Divinylbenzene thermosetting copolymers,IV.POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2002Good damping properties Abstract New polymeric materials have been prepared by the cationic copolymerization of regular soybean oil, low saturation soybean oil, i.e. LoSatSoy oil, or conjugated LoSatSoy oil with styrene and divinylbenzene, norbornadiene or dicyclopentadiene initiated by boron trifluoride diethyl etherate (BF3·OEt2) or related modified initiators. The effects of the stoichiometry, the type of soybean oil and the alkene comonomer on the damping behavior of the resulting polymers have been investigated. The damping properties have been quantitatively evaluated by the loss tangent maximum (tan ,)max, the temperature range ,T for efficient damping (tan ,,>,0.3), and the integrals of the linear tan , v. temperature curves (tan , area, TA). These bulk materials are composed primarily of soybean oil-styrene-divinylbenzene random copolymers with considerable variability in the backbone compositions. The good damping properties of the soybean oil polymers are presumably determined by the presence of fatty acid ester side groups directly attached to the polymer backbone and the segmental heterogeneities resulting from crosslinking. In general, crosslinking reduces the (tan ,)max and the TA values, but broadens the region of efficient damping (,T). Soybean oil polymeric materials with appropriate compositions and crosslink densities are capable of efficiently damping over a temperature region in excess of 110,°C and provide noise and vibration attenuation over broad temperature and frequency ranges. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||