A one-pot method for the preparation of latices of telechelic oligomers, by ozonolysis of latices of polymers containing main-chain unsaturation

摘要

Poly(methyl methacrylate-co-butadiene), Poly(butyl methacrylate-co-butadiene) and Poly(methyl methacrylate-co-2,3-dimethyl butadiene) latices (a.k.a. latexes) were prepared by monomer-starved emulsion polymerization. The polymerizations were followed by GPC. It was found that the molecular-weight distribution did not alter significantly with conversion if the polymerizations were carried out at a feed rate of 0.03 cm(3) s(-1) per 1000 cm(3) of reaction medium and a temperature of 70 degrees C. Slower rates of monomer addition led to broadening of the molecular-weight distribution. The resultant latices were swollen with varying amounts of toluene. Ozonolysis of the swollen and nonswollen latices yielded latices of polymer ozonides. Oxidation, with selenium oxide/hydrogen peroxide reagent, converted the ozonides to latices of carboxylic acid or methyl ketone ended telechelic oligomers. It was found that the molecular weights of the oligomers were a function of toluene concentration. Colloidal stability was found to be a function of end-group structure. Thus, carboxylic acid end groups impart extra stability to the colloid while methyl ketone end groups do not. (C) 1997 John Wiley & Sons, Inc.