The homogeneous and the dispersion polymerization and copolymerization of methacryloylterminated poly(oxyethy1ene) (MMA-PEG) and of p-vinylbenzyl-terminated poly(oxyethy1ene) (St-PEG) macromonomers and styrene, initiated by a radical initiator, was investigated using conventional gravimetric and NMR methods at 60 "C. The batch polymerizations in N,N-dimethylformamide and in ethanol/water were conducted to either low or high conversion. The fractional conversion rates of the solution polymerization and copolymerization indicate that the homopolymerizations of macromonomers involve steady-state conditions, whereas copolymerizations proceed under non-stationary conditions. The ratios of the rate constants for propagation and termination (k,/kF5) for polymerization and copolymerization of MMA-PEG and St-PEG are by one order of magnitude higher than that for styrene. The increase in k,/kF5 is more pronounced in dispersion polymerization, which is ascribed to the decrease of both k, and k,.

The free radical copolymerization of poly(t‐butyl methacrylate) (PBMA) macromonomer with styrene in ethanol give monodispersed microspheres with 0.8‐1.6 μm diameter. The resulting microspheres were treated with HCl solution to convert into anionic microspheres having poly(methacrylic acid) chains. ESCA analysis of the microsphere surface suggested that PBMA chains were favorably located on the surface of the microspheres. The particle size of the microspheres decreased with increasing molecular weight and concentration of the macromonomer. Water dispersibilities of the microspheres were evaluated by measuring the relative turbidity of the suspension of microspheres as a function of pH. The results show that they were strongly dependent on pH. © 1995 John Wiley & Sons, Inc.

ABSTRACT:The kinetics of dispersion copolymerization of methacryloyl-terminated poly(oxyethylene) (PEO-MA) and p-vinylbenzyl-terminated (PEO-St) polyoxyethylene macromonomers and styrene (St), initiated by a water-and/or oil-soluble initiator, was investigated using conventional gravimetric and NMR methods at 60ЊC. The batch copolymerizations in the water/ethanol continuous phase were conducted to high conversion. The rate of polymerization was described by the curve with a maximum at very low conversion. The initial rate of polymerization and the number-average molecular weight were found to decrease with increasing [PEO-MA], and the decrease was more pronounced in the range of a high macromonomer concentration. The rate per particle (at ca. 20% conversion) was found to be proportional to the 01.55th, the particle size to the 00.92nd, and the number of particles (at final conversion) to the 3.2nd power of [PEO-MA], respectively. At the beginning of polymerization the continuous phase is the main reaction locus. As the polymerization advances, the reaction locus is shifted from the continuous phase to the polymer particles. The transform of the reaction loci from the continuous phase to the polymer particles increases the rate of polymerization and the polymer molecular weights. The increase of the weight ratio PEO-MA/St favors the formation of monodisperse polymer particles, the colloidal stability of dispersion, and the formation of a larger number of polymer particles.

No abstract