Indefinitely active aqueous cationic polymerizations,part I: Low cost,recyclable initiator systems

This article describes the first example of an aqueous cationic polymerization that utilizes a low cost, safe, and highly recyclable initiator system (phosphotungstic acid) that retains its activity indefinitely. Quantitative yields of low to medium molecular weight polymers of p-methoxystyrene and N-vinylcarbazole are obtained within minutes to hours. Polymerization is first order in both monomer and phosphotungstic acid. Negatively charged surfactants suppress polymerization; whereas, nonionic soaps increase the reaction rate and reduce both polymer molecular weight and polydispersity index. Herein, the discovery of a new form of aqueous cationic polymerization involving the condensation of the alcoholic derivative of p-methoxystyrene, 1-(4-methoxyphenyl)ethanol, is also disclosed.     

Catalytic chain transfer polymerisation (cctp) of methyl methacrylate: Effect of catalyst structure and reaction conditions on chain transfer coefficient

Catalytic chain transfer polymerisation of methyl methacrylate has been investigated by a range of cobalt(II) complexes. The effect of catalyst structure, reaction temperature and solvent has been examined. At 60°C in the absence of solvent, the chain transfer coefficient, Cs, for MMA and cobaloximes modified by bridging BF₂ groups e.g. 3 is found to be 40,900, this is constant over a wide mass range. Cs is lowered when catalysts of larger cross sectional area are used supporting a diffusion controlled process. Co-ordinating solvents suppress Cs by competing for coordination of the Co(II) effectively reducing the concentration of active species. No conclusions can be drawn regarding the effect of temperature and thus the activation energy of the process. CCTP lowers the observed rate of polymerisation.