Micellar effect on the polymerization. III. kinetics of polymerization of acrylonitrile initiated by Ce(IV)–glucose system in presence of cationic micelles

2003

ABSTRACT:The rate of polymerization of acrylonitrile, using the Ce(IV)-cyclohexanone redox system as an initiator, was studied kinetically, in the presence of 0.015M sodium dodecyl sulfate (SDS), over a temperature range of 25-45°C. The rate of polymerization (R P ), percentage of monomer conversion, and rate of Ce(IV) consumption (ϪR Ce ) were found to increase with the concentration of SDS, above its CMC. The effect of [AN], [Ce(IV)], [H ϩ ], and the ionic strength were also studied. The overall activation energies for the polymerization processes were computed to be 23.14 and 17.64 kcal/mol in the absence and presence of 0.015M SDS. A suitable kinetic mechanistic scheme for the free-radical mechanism was proposed.

Acrylonitrile polymerization initiated by Ce(IV)–cyclohexanone redox system in presence of surfactant

2003

Effects of surfactants on acrylonitrile polymerization initiated by a Cr(VI)–cyclohexanone redox system: A kinetic study

Sinha

2003

ABSTRACT:The polymerization of acrylonitrile (AN) was kinetically studied with a Cr(VI)-cyclohexanone (CH) redox system as an initiator from 25 to 45°C in the presence of a surfactant. The rate of polymerization and the percentage of the monomer conversion increased as the concentration of the anionic surfactant [sodium dodecyl sulfate (SDS)] increased above its critical micelle concentration. However, the cationic surfactant (cetyltrimethylammonium bromide) reduced the rate considerably at higher concentrations, whereas the nonionic surfactant (TX-100) had no effect on the rate. The effects of the Cr(VI), CH, AN, and H ϩ concentrations and the ionic strength on the rates were also examined. The presence of 0.015M SDS reduced the overall activation energy of the polymerization by 5.55 kcal/mol with respect to that in the absence of the surfactant. With increasing SDS concentration, the viscosity-average molecular weight also increased. A suitable mechanistic scheme was proposed for the polymerization process.

Tl(III) initiated polymerization of methyl methacrylate in micellar phase

Sinha

2004

ABSTRACT:The polymerization kinetics of methyl methacrylate (MMA) was studied, using Tl(III)-cyclohexanone (CH) redox system as initiator, in the presence of emulsifier [i.e., sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and thallium triacetate (TX-100)] over a temperature range of 25-45°C. The effect of various concentrations of MMA, Tl(III), cyclohexanone, H ϩ , and varying ionic strengths on the rate of polymerization, rate of Tl(III) consumption (ϪR Tl ), and the percentage of monomer conversion were examined in the presence of 0.015M SDS. The kinetic results of polymerization in the absence and presence of 0.015M SDS were compared in terms of overall activation energy (E a ) for the process. The viscosity-average molecular weight (M V ) of the polymers, obtained in the presence of varying concentrations of anionic surfactant (SDS), was also determined.