Graft polymerization of methyl methacrylate onto polyvinyl alcohol using Ce4+ initiator

Abstract

Methyl methacrylate (MMA) was graft polymerized onto polyvinyl alcohol (PVA) using ceric ammonium sulfate as an initiator in aqueous medium. The grafting efficiency of MMA was studied as a function of monomer and initiator concentration, time, pH, and temperature. Grafting efficiency was found to be optimum at a particular level of ceric ammonium sulfate (3.16 ϫ 10, and time (4 h). The probable reasons for the influence of reaction variable on the observed trend of MMA towards grafting have been discussed. Acid hydrolysis and infrared spectroscopy were used for the confirmation of graft copolymer formation. Thermogravimetric analysis of PVA and a representative graft copolymer were studied. The solubility/swellability and the gelatinization characteristics are also reported.

Preparation and characterization of graft copolymerization of ethyl acrylate onto hydroxypropyl methylcellulose in aqueous medium

“…It can be observed from this figure that, within the backbone concentration range studied, G consistently decreases with increasing amounts of HPMC but that G E increases only slightly over the full range of HPMC content studied. The results of Figure 3 can be explained on the basis of the fact that although the weight of the grafted PEA chains may increase with increasing HPMC concentrations, the decrease in the monomer-to-backbone ratio lowers G. In addition, the number of HPMC macroradicals that can interact with each other to terminate the reaction increases with increasing HPMC, which can make the termination rate of graft copolymerization surpass the rate of initiation, thereby also lowering G. Similar results have also been reported in the case of ethyl methacrylate being grafted onto polyvinyl alcohol (Chowdhury 1998). Figure 4 shows the influence of the reaction temperature on G and G E : G increases with increases in the reaction temperature from 50 to 65°C but decreases with as the reaction temperature surpasses 65°C, while G E decreases consistently with increases in the reaction temperature.…”

Effect of dimethylaminoethyl methacrylate on the graft copolymerization of ethyl acrylate onto hydroxypropyl methylcellulose in aqueous medium

“…It can be observed from this figure that, within the backbone amount range studied, G consistently decreases by increasing the amount of HPMC but G E increases over the full range of HPMC content studied. The results of Figure 8 can be explained on the basis of the fact that although the weight of the grafted polymer chains may increase with the increase in HPMC amount, the decrease in the monomer-tobackbone ratio lowers G. In addition, the HPMC macroradicals that can interact with each other to terminate the reaction increase with the increase in HPMC, which can make the termination rate of graft copolymerization become faster than the rate of initiation thereby also lowering G. Similar results, are also reported in the case of grafting of ethyl methacrylate onto polyvinyl alcohol (Chowdhury 1998). Figure 9 presents the influence of reaction temperature on G and G E .…”

Selective Aerobic Oxidation of Methanol in the Coexistence of Amines by Nanoporous Gold Catalysts: Highly Efficient Synthesis of Formamides

“…The grafting method needs free radicals or peroxides to modify the surface of polymers 25. They can be formed by ionization radiation28–30 or ultraviolet,31, 32 plasma,33, 34 electron beam,35 or chemical initiators 36. Among these techniques, ionization radiation is known to be one of the more useful methods because active radicals are created on the polymer uniformly.…”