Photoinitiated precipitation polymerization in liquid CO2: Fast formation of crosslinked poly(acrylic acid-co-methoxy polyethylene glycol acrylate) microspheres

摘要

Precipitation polymerisation is a technique to prepare crosslinked polymeric microspheres in the absence of any stabilisers or surfactants, first reported by Stover and Li in 1993. In recent years, supercritical carbon dioxide has been used as a reaction medium. However, because polymerisation is thermally initiated, high pressures and special equipment were necessary. Photoinitiated polymerisation has been introduced, which allows fast reaction rates and mild conditions. The reaction can proceed at temperatures below the critical temperature of carbon dioxide and therefore liquid carbon dioxide can be used as the reaction medium.