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The reactivity of copolymer silane composed of maleic anhydride in the modification of fine colloidal silica was studied.
The reaction of colloidal silica of 10 and 45-nm diameter with trimethoxysilyl-terminated poly(maleic anhydride-co-styrene) [P(MA-ST)] and poly(MA-co-methyl methacrylate) in tetrahydrofuran resulted in effective surface modification without particle aggregation. From the
results that the reaction using the polystyrene silane of low molecular weight led to partial aggregation, it was suggested
that the steric interaction between relatively rigid copolymer chains having a maleic anhydride moiety adsorbed on the silica
prevented the aggregation in the reaction. The 29Si cross-polarization magic-angle-spinning NMR spectra of P(MA-ST)-modified silica showed that the polymer silane was bound
to the silica surface by the direct reaction with silica hydroxyl groups and via the polymerization.
Received: 27 June 2001 Accepted: 6 September 2001 相似文献
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Zbigniew Florjaczyk Wodzimierz Krawiec 《Journal of polymer science. Part A, Polymer chemistry》1989,27(12):4099-4108
The relative reactivity of vinyl monomers characterized by electron donor and electron acceptor properties in free radical terpolymerization with maleic anhydride has been compared on the basis of product composition analysis. Terpolymers containing ca. 50 mol % of maleic anhydride were obtained in systems containing two electron donor monomers and the relative reactivity of them increases in the following order: 1-hexene < propylene ≈ isobutylene < styrene < isoprene < 1,3-butadiene. In systems consisting of an electron donor monomer and two electron acceptor monomers (i.e., maleic anhydride and an acrylic monomer), the composition of the terpolymers formed depends essentially on the resonance stabilization of the electron donor monomer. With a rise of their resonance stabilization, the content of acrylic monomeric units decreases and the share of alternating sequences of the electron donor and maleic anhydride monomeric units increases. It was found that the relative reactivity of maleic anhydride in all such systems is much greater than that predicted on the basis of reactivity ratios determined in binary systems. The relative reactivity of the studied acrylic monomers decreases in the order: methyl methacrylate > methyl acrylate > acrylonitrile. In the presence of catalytic amounts of ZnCl2 the content of acrylic monomeric units clearly increases in the products obtained, mainly as a result of homopropagation. The results obtained are discussed in terms of the classical mechanism of propagation and the complex participation model. 相似文献
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Copolymerisation of maleic anhydride with tert.-butyl methacrylate and trimethylsilyl methacrylate was studied. Both monomers form random copolymers with maleic anhydride and in both cases the acceptor monomer is incorporated preferentially into the copolymer. Maleic anhydride which does not homopolymerise has reactivity ratios of approximately zero. The esters have reactivity ratios of 12.8 for trimethylsilyl methacrylate and 2.95 for tert.-butyl methacrylate. Thermal behavior and molar masses were investigated as a function of composition. Conditions for hydrolysis of the trimethylsilyl ester groups to give free acid groups have been established. 相似文献
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Sueo Machi Takashi Sakai Masao Gotoda Tsutomu Kagiya 《Journal of polymer science. Part A, Polymer chemistry》1966,4(4):821-828
The copolymerization of ethylene with maleic anhydride was carried out with γ-radiation and a radical initiator, i.e., 2,2′-azobisisobutyronitrile and diisopropyl peroxydicarbonate under pressure at various reaction conditions. The homopolymerization of neither monomer was observed in this system. In the γ-ray-initiated copolymerization the G value (polymerized monomer molecules per 100 e.v.) was shown to be between 103 and 104. It was found that the dose rate exponent of the rate is approximately unity, and the rate is proportional to the amount of ethylene monomer. Apparent activation energies of 1.8 and 27.5 kcal./mole were obtained for γ-ray-initiated and AIBN-initiated copolymerization, respectively. Since the composition of copolymer is independent of monomer molar ratio and the molar ratio of ethylene to maleic anhydride in the polymer is approximately unity, the monomer reactivity ratios were obtained as rE ? 0 and rM ? 0 for γ-ray-initiated polymerization at 40°C. Alternating copolymerization was, therefore, concluded to occur. Infrared analysis of the copolymer is almost consistent with this. The copolymer in the solid state is amorphous. It is soluble in water, cyclohexane, and dimethylformamide and insoluble in lower alcohols, ether, and aromatic hydrocarbons. The aqueous solution of polymer gave a strong acid. 相似文献
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The reactions of some furfuryl alcohols with maleic anhydride have been reinvestigated and, for the first time, conditions defined for the production of intramolecular Diels-Alder adducts. In basic conditions these adducts yield phthalides in high yields. 相似文献
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The grafting of maleic anhydride onto carbon black surface based on the Diels–Alder addition via ultrasonic irradiation was investigated. Fourier transform infrared spectroscopy (FT‐IR) and thermogravimetric analysis (TGA) were used to determine the chemical structure of the resulting products. The anhydride ring in the modified products can be opened into two carboxylic groups. Accordingly, the carboxylated carbon black was analyzed quantitatively through acid‐based titration to determine the concentration of anhydride ring on the modified carbon black's surface. The grafted molecules amount calculated from the concentration of the anhydride ring was consistent with the results of TGA data. Comparison of zeta potential measurement demonstrated that there were more negative charges attached to the surface of carbon black after ultrasonic modification. TEM observations showed that the conglomeration degree of modified carbon black decreased more than that of initial carbon black. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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E. Clar 《Tetrahedron letters》1973,14(36):3471-3472
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Koji Nishihara Akihiro Suzuoka Naokazu Sakota 《Journal of polymer science. Part A, Polymer chemistry》1973,11(9):2315-2327
Methacryloyl-L -valine methyl ester (MAVM) and maleic anhydride (MAn) were photopolymerized without initiator in dioxane at 35°C. Copolymer having a 1:1 molar ratio of the monomers was obtained regardless of both molar ratio of monomers in the feed and polymerization time. The circular dichroism (CD) spectrum of the copolymer before and after hydrolysis showed the induction of asymmetric centers into the polymer main chain. Spectroscopic and kinetic studies suggested the alternating and stereoregular copolymerization of MAVM and MAn, in which a charge transfer complex with a 1:1 molar ratio of monomers participated. 相似文献
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Chemistry of Natural Compounds - The reaction of yeast inorganic pyrophosphatase with an excess of maleic anhydride at 2° C for 5 min leads to the acylation of all ε-amino groups of... 相似文献
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Conclusions The reaction of yeast inorganic pyrophosphatase with an excess of maleic anhydride at 2° C for 5 min leads to the acylation of all -amino groups of lysine residues.The protective groups are completely removed at pH 3.5 for 16 hr at 60° C. Acylation with maleic anhydride is accompanied by the dissociation of the yeast inorganic pyrophosphatase into its subunits.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 1, pp. 123–127, 1970 相似文献
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The complex formation constants for styrene (donor)-acrylonitrile (acceptor) and styrene-maleic anhydride (acceptor) systems are found to be 0.19 ± 0.01 and 0.28 ± 0.01 l/mol (1H NMR, CCl4, 298 K); the same values are characteristic for three-component systems of these monomers. The calculated ΔH 0 values (the AM1 method) for styrene-acrylonitrile (C1) and styrene-maleic anhydride (C2) complexes comprise ?1.24 and ?2.30 kJ/mol. Changes in charges on double bonds of complex-bonded molecules are in the range from 0.001 to 0.006 au. These values are typical of π-π complexes. By analyzing the composition and rate of bulk copolymerization (333 K, 0.03 mol/l AIBN), we have shown that two complexes are involved in chain propagation: r 1 = $ k_{2C_1 } /k_{2C_2 } $ = 0.26 ± 0.015 and r 2 = $ k_{3C_2 } /k_{3C_1 } $ = 4.17 ± 0.143. 相似文献
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S. G. Mamedova N. Sh. Rasulov Z. M. Rzaev 《Journal of polymer science. Part A, Polymer chemistry》1987,25(2):711-717
Some regularities of radical alternating copolymerization of maleic anhydride with allyl chloroacetate are studied. The formation of donor–acceptor complexes between comonomers with complexing constant Kc = 0.052 L/mol is found using 1H NMR spectroscopy. The kinetic parameters for this copolymerization reaction are found and the quantitative contribution of monomer complexes to chain-growth radical reactions is calculated. It is shown that either a “free-monomer” mechanism (dilute solutions) or a “mixed” mechanism (concentrated solutions) prevails for chain growth during radical copolymerization depending on total monomer concentration. It is found that inhibition of degradative chain transfer in the course of the reaction studied takes place owing to the presence of α-chlorine atom in the allyl chloracetate molecule and formation of charge transfer complex. 相似文献
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d-Limonene (Lim), a nonconjugated 1,5-diene, was copolymerized with maleic anhydride (MAn) in tetrahydrofuran with α,α′-azobisisobutyronitrile as initiator. The composition, spectral analyses, and other physical properties of the resulting copolymer and its hydrolysed product suggest that Lim readily undergoes an inter-intramolecular cyclocopolymerization with MAn, leading to a 1:2 alternating copolymer. The findings and the proposed cyclocopolymerization mechanism are consistent with participation of a charge-transfer complex of the comonomers in the propagation step. The copolymers are optically active and their CD spectra are characterized by dichroic bands attributable to electronic transitions of carbonyl or carboxylic chromophores. 相似文献
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A series of polyethylene glycol grafted vinylpyrrolidone–maleic anhydride copolymers [P(VMP)] was synthesized by radical copolymerization of vinylpyrrolidone, maleic anhydride and polyethylene glycol maleic acid monoester. Escherichia coli l -asparaginase was chemically modified with these copolymers. The modified l -asparaginase exhibited the complete loss of antigenicity towards anti-asparaginase serum from rabbit. The highest enzyme activity of the modified l -asparaginase without antigenicity was retained by 59% of the nonmodified one. The modified enzyme was also more resistant to trypsin in vitro. When tested in vivo, the native l -asparaginase was quickly cleared from the plasma of rabbits (half-life time: t1/2=1.2 hr), whereas the modified enzyme showed prolonged clearance from plasma (t1/2=53 hr). © 1997 John Wiley & Sons, Ltd. 相似文献