Comblike polymers with octadecyl side chain and carboxyl functional sites: Scope for efficient use in miniemulsion polymerization

The scope for the efficient use of comblike polymers to synthesize polystyrene latexes with a narrow distribution of particles in a size range of 100-250 nm has been demonstrated. The polymers comprising of octadecyl side chains with a statistical distribution of carboxylic groups and in the molecular weight range of ca. 4 x 10(4) have been synthesized by free radical polymerization reaction. The characterization of polystyrene latexes synthesized using these comblike polymers with different acid compositions, 0.11 and 0.31 mole fraction of both acrylic and methacrylic acid in the feed, with respect to the particle size, the surface coverage of the latex surface with carboxylic groups, and the surface tension of the latex throws interesting information on the probable; mechanism underlying this typical miniemulsion polymerization system. The high efficiency of the polymer in miniemulsion polymerization suggests that the polymer undergoes a typical reorganization process with octadecyl groups covering the styrene oil phase and the retaining carboxylate groups being located at the interface. The stability of the miniemulsion droplets prior to polymerization against aging is in support of the suppression of Ostwald ripening and coalescence processes and proves that the polymer acts both as a surfactant and-although located at the interface-as an osmotic agent. Preservation of the original particle size and distribution throughout polymerization underlines the predominance of droplet nucleation.