PRECIPITATION POLYMERIZATION OF ACRYLIC-ACID IN SUPERCRITICAL CARBON-DIOXIDE

We report the successful precipitation polymerization of acrylic acid in supercritical carbon dioxide at pressures ranging from 125 to 345 b ar utilizing AIBN as a free radical initiator. Analyses by gel permeat ion chromatograpy (GPC) and scanning electron microscopy (SEM) indicat e that for the pressure range studied there is no appreciable effect o n product molecular weight, molecular weight distribution, or particle size or morphology. In addition, effective molecular weight control w as demonstrated for precipitation polymerizations of acrylic acid in C O2 through the use of ethyl mercaptan as a chain transfer agent.