Optimization of the polymerization process of sulfinyl precursor polymers toward poly(p-phenylenevinylene)

The prerequisites for the polymerization process of sulfinyl monomers toward precursor polymers for poly(p-phenylenevinylene) were investigated. In this process, proton abstraction affords the premonomer anion, which is converted to the actual monomer, viz, a p-xylylene derivative. These p-xylylene derivatives polymerize spontaneously without external initiation. In hydrogen bond donor solvents (HBD solvents) like alcohols, three products can be isolated. High molecular weight polymer is formed together with a residual fraction that consists of a minor amount of premonomer and a large amount of solvent-substituted product. These solvent-substituted products are most likely formed by addition of a solvent anion to the actual monomer and cannot participate in the polymerization process anymore. Solvent substitution is therefore an important side reaction and has to be avoided. It was found that, in branched alcohols such as s-butanol, conversion of premonomer to actual monomer is very efficient, resulting in a rapid buildup of p-xylylene derivative. In this way the polymer yield was increased to 90%.