The aqueous polymerization of methyl methacrylate initiated by the bromate-thiourea redox system in dilute HC1 has been investigated under nitrogen atmosphere. The rate of polymerization increases with increasing concentration of thiourea in the range 5 × 10?3?10 × 10?3 M. The percentage of conversion increases with increasing concentration of the catalyst, but beyond 1.5 × 10?2 M, there is a decreasing trend in the rate of polymerization. The rate of polymerization increases with increasing monomer concentration, but beyond 0.184 M the polymerization rate decreases due to gel effect. The rate of polymerization increases with temperature up to 35°C and beyond 40°C a decreasing trend is noticed. The effect of water miscible organic solvents, certain neutral salts on the rate of polymerization has also been investigated. 相似文献
Abstract Poly(sulphur oxide) has been prepared by the low temperature thermal decomposition of the lower oxides of sulphur. This yellow, elastic solid resists water hydrolysis. It is unstable at room temperature when stored under vacuum and decomposes slowly to a powdery yellow white cyclic(sulphur oxide) and sulphur dioxide. In the presence of silicon tetrachloride, the thermal decomposition gives rise to an adduct of the lower oxide of sulphur along with the poly(sulphur oxide). The adduct hydrolyses to silica, hydrogen chloride, hydrogen sulphide and hydrogen sulphite. Based on the analysis of the hydrolysed products and the IR data, the adduct is assigned a formula of SiCl4·2(SO), in which the silicon is hexacoordinated. 相似文献
A series of three poly(3‐hexylthiophene) functionalized either with a cyanoacetic acid (CA) or a rhodanine‐3‐acetic acid anchoring groups were synthesized and characterized. The TiO2 based dye‐sensitized solar cells have been fabricated and performances were tested. We show that shorter chain length (15 thiophene units) linked to CA binding group gives good performances as Jsc, Voc, FF and η(%) were 6.93(mA · cm−2), 0.65(V), 0.67 and 3.02%, respectively. A maximum IPCE of ≈50% at 500 nm was recorded with a liquid electrolyte, under AM 1.5 simulated solar irradiance.
Hantzsch 1,4-dihydropyridines and polyhydroquinoline derivatives were synthesized in good yields by PEG-mediated, catalyst–free synthesis under solvent-free conditions. The products were directly recrystallized from hot methanol. The reaction gave excellent yields with low- as well as high-molecular-weight polyethylene glycols. 相似文献
Abstract The graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10?5 mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases with increasing concentration of HCIO4 and with increasing temperature. Inhibitors like picryl chloride and hydroquinone significantly decrease the extent of grafting. Alcoholic solvents at a solvents/water ration of 10:90 seem to constitute the most favorable medium for grafting. A suitable reaction scheme has been proposed, and the activation energy calculated from the Arrhenius plots. 相似文献
Polymerization of methyl methacrylate in visible light was studied at 30°C using the α-picoline-chlorine charge-transfer complex as the photoinitiator. Analysis of kinetic and other data indicate that polymerization proceeds via a radical mechanism and that termination is initiator dependent. Chain termination via degradative chain (initiator) transfer appears to be significant. 相似文献
The vinyl polymerization of acrylonitrile initiated by the redox system Mn3+-cyclohexanol was investigated in aqueous sulfuric acid in the temperature range of 30–45° C. The rate of polymerization Rp and the rate of Mn3+ ion disappearance were measured. The effects of certain water-miscible organic solvents and certain anionic, cationic, and nonionic surfactants on the rate of polymerization were investigated. Based on the results obtained, a suitable reaction mechanism involving the formation of a complex between Mn3+ and the alcohol, whose decomposition yields the initiating free radical with the polymer chain being terminated by the mutual combination of growing chains is suggested. 相似文献