Preparation of Three-Armed Star Polystyrene by Reaction of Prepolymer Having a Terminal Functional Group with Triisocyanate

Abstract

Polystyrene prepolymers having hydroxyl or amino groups at their ends were prepared by anionic polymerization techniques. The linking reactions of these prepolymers with triisocyanate derived from lysine were carried out under various conditions and their efficiencies of conversion to three-armed star polymers were determined by GPC measurements. The reaction of the prepolymer having an –OH group with triisocyanate under catalysis of tri-n-butyltin oxide as well as the direct reaction of the intermediate polystyryl anion with triisocyanate was found to be most effective for preparation of star polystyrene having three arms. The star polymer thus prepared was successfully isolated by fractionation procedures after treating the reaction mixture with reactive polystyrene gels containing sulfonyl chloride or isothiocyanate groups. The number of arms of the isolated star polymer was confirmed to be virtually three by the ratio of the number-average molecular weight of the star polymer to that of the corresponding prepolymer.