Silica gel supported co(acac)(2) catalyst in the controlled radical polymerization of vinyl acetate: an easy and practical method to make crystallized poly(vinyl acetate) in a one step process

摘要

Cobalt-mediated radical polymerization (CMRP) of vinyl acetate (VAc) has been suggested as one of the major methods to reduced some of the problems in the synthesis of Poly(vinyl acetate) (PVAc), but the color impurities have been the major disadvantage of this method. An easy and practical method to make a crystallized PVAc in a one step process is to use silica gel particles. The particles have been used as a catalyst support of cobalt((II)) acetylacetonate (Co(acac)(2)). It was found that using silica gel supported-Co(acac)(2) in VAc polymerization yields polymers with controlled molecular weight, narrow molecular weight distribution, and high purity. For the silica gel supported CMRP (SS-CMRP) changing the polymerization mechanism resulted in a 2.5 times increase in polymerization rate (k(app)) and a drop in the induction time while maintaining the control of the VAc polymerization. In addition PVAc synthesized through SS-CMRP method compared to the one synthesized using unsupported-CMRP has a higher crystallinity.