Reactivity ratios for the terpolymerization of methyl methacrylate, vinyl acetate, and molecular oxygen

The copolymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) under high oxygen pressure was investigated. Copolyperoxides of various compositions were synthesized by the free-radical-initiated oxidative copolymerization of NMIA and VAc monomers. The copolyperoxide compositions obtained from H-1 and C-13 NMR spectra were used for determining the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of MMA units statistically placed in the copolyperoxides. A theoretical analysis based on semiempirical AM1 calculations was performed to support the reactivity ratios. NMR studies showed irregularities in the copolyperoxide chain due to the cleavage reactions of the propagating peroxide radical. Thermal analyses of the copolyperoxides by differential scanning calorimetry gave evidence for the presence of alternating peroxide units in the copolyperoxide chain, The activation energies of thermal degradation suggested that degradation was controlled by the dissociation of the peroxide (-O-O-) bond in the backbone of the copolyperoxide chain

Synthesis and characterization of copolyperoxides of indene with styrene, \alpha -methylstyrene, and \alpha -phenylstyrene

The oxidative copolymerization of indene with styrene, \alpha -methylstyrene, and \alpha -phenylstyrene is investigated. Copolyperoxides of different compositions have been synthesized by the free-radical-initiated oxidative copolymerization of indene with vinyl monomers. The compositions of the copolyperoxides obtained from the ^1H and ^1^3C NMR spectra have been used to determine the reactivity ratios of the monomers. The reactivity ratios indicate that indene forms an ideal copolyperoxide with styrene and \alpha -methylstyrene and alternating copolyperoxides with \alpha -phenylstyrene. Thermal degradation studies via differential scanning calorimetry and electron-impact mass spectroscopy support the alternating peroxide units in the copolyperoxide chain. The activation energy for thermal degradation suggests that the degradation is dependent on the dissociation of the peroxide (-O-O-) bonds in the backbone of the copolyperoxide chain. Their flexibility has been examined in terms of the glass-transition temperature

Oxidative copolymerization of indene with p-tert-butylstyrene: Synthesis, characterization, thermal analysis, and reactivity ratios

Copolyperoxides of indene and p-tert-butylstyrene of different compositions were synthesized by free-radical-initiated oxidative copolymerization. The compositions of the copolyperoxides, obtained from H-1 and C-13 NMR spectra, were used to calculate the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of indene units in random placement in the copolyperoxides. Thermal-degradation studies by differential scanning calorimetry and electron-impact mass spectrometry supported alternating peroxide units in the copolymer backbone. The activation energy for thermal degradation suggested that the degradation was dependent on the dissociation of the peroxide (-O-O-) bonds in the backbone of the copolyperoxide chain. The flexibility of the copolyperoxides was examined in terms of the glass-transition temperature

Free Radical Oxidative Copolymerization of Indene with Vinyl Acetate and Isopropenyl Acetate: Synthesis and Characterization

Copolyperoxides of different compositions of indene with vinyl acetate and isopropenyl acetate were synthesized by the free radical-initiated oxidative copolymerization. The compositions of copolyperoxides obtained from $^1H-$ and ^1^3C-NMR spectra have been used to determine the reactivity ratio of the monomers. The reactivity ratios reveal that the copolyperoxides contain a larger proportion of the indene units in random placement. The NMR studies further suggest irregularities in the copolyperoxide chain possibly due to the cleavage reactions of the propagating peroxide radical. The thermal analysis by differential scanning calorimetry (DSC) supports the alternating peroxide units in the copolymer chain. The activation energy for the thermal degradation suggests that the degradation is dependent on the dissociation of the peroxide (-O-O-) bonds in the copolyperoxide chain

Carbohydrate Containing Cross-linked Hydrogels Used for the Removal of Water Soluble Cationic Dyes

Gels are 3-dimensional (3-D) networks of polymer chains, where the monomers constituting the polymers are formed through covalent or non-covalent interactions. There are two types of polymer gels,hydrogels or organogels, respectively, dependent upon the solvent that solvates the polymer chains.1 Hydrogels have a variety of applications in tissue engineering, drug delivery, protein chromatography and enzyme recycling etc.2,3,4 This poster will report our investigation of the synthesis and characterization of a novel class of carbohydrate-based gel networks. The nature of the resultant gels can tuned from organogels to hydrogel by a simple deprotection approach. The hydrogels can absorb a model drug (the dye Rhodamine-B, methylene blue) and release it at certain time intervals. The absorption and release of the dye was measured by UV-Vis spectroscopy. The interior morphology of the organogels and hydrogels was studied by field emission scanning electron microscopy (FE-SEM)

Determination of the reactivity ratios for the oxidative copolymerizations of indene with methyl, ethyl and butyl acrylates

Full Paper: The copolyperoxides of various compositions of indene with methyl acrylate, ethyl acrylate and butyl acrylate have been synthesized by the free-radical-initiated oxidative copolymerization. The compositions of copolyperoxide obtained from H-1 and C-13 NMR spectra have been used to determine the reactivity ratios of the monomers. The copolyperoxides contain a greater proportion of the indene units in random placement. The NMR studies have shown irregularities in the copolyperoxide chain due to the cleavage reactions of the propagating peroxide radical. The thermal analysis by differential scanning calorimetry suggests alternating peroxide units in the copolyperoxide chain. From the activation energy for the thermal degradation, it was inferred that degradation occurs via the dissociation of the peroxide (O-O) bonds of the copolyperoxide chain. The flexibility of the polyperoxides in terms of glass transition temperature (T-g) has also been examined

Synthesis of poly(1,3-diisopropenylbenzene peroxide)

1009-1011Poly(1,3-diisopropenylbenzene peroxide) (PDIPBP) has been prepared from 1,3-diisopropenylbenzene by free-radical-initiated oxidative polymerization. The presence of peroxide group (-O-O-) in the polymer backbone has been confirmed by differential scanning calorimetry (DSC) and FTIR spectroscopy. Thermal degradation studies using DSC have revealed that PDIPBP degrades highly exothermically and the measured heat of degradation (-295.4 cal g-1) is slightly higher than that reported earlier for vinyl polyperoxides

Polymerization of vinyl acetate with styrene and α-methylstyrene under high oxygen pressure

1282-1287The polymerization of vinyl acetate with styrene and a-methyl styrene of various compositions has been studied by the free radical-initiated oxidative polymerization. The compositions of the resultant polymers obtained from 1H and 13C{H1} NMR spectra have been utilized to determine the reactivity ratios of the monomers. The reactivity ratios reflect the tendencies of the two monomers towards consecutive homopolymerization. The NMR studies reveal irregularities in the chain due to the cleavage reactions of the propagating peroxide radical. The thermal degradation study by differential scanning calorimetry (DSC) supports alternating peroxide units in the polymer. The activation energy for the thermal degradation suggests that the degradation is controlled by the dissociation of the peroxide (-O-O-) bonds of the polymer

Thermal degradation studies of para-substituted poly(styrene peroxide)s

The thermal degradation of a series of para-substituted poly(styrene peroxide)s with electron-donating [CH3, C(CH3)(3)] and electron-attracting (Br) substitutents are investigated by thermogravimetric analysis (TGA). The results indicate that the Hammett relationship can describe quantitatively the trends in maximum rate of polymer decomposition (T-max) observed in TGA and thus thermostability of substituted poly(styrene peroxide)s depends only on the electronic nature of substituents and their ability to stabilize macroradicals formed during chain scission. The experimental results are also substantiated by thermochemical calculations. (C) 2002 Elsevier Science Ltd. All rights reserved