2-COMPONENT INITIATOR SYSTEMS FOR THE RING-OPENING POLYMERIZATION OF OLIGOMERIC CYCLIC BISPHENOL-A CARBONATES - STUDIES WITH IN-SITU GENERATED WITTIG SALTS

A two-component initiator system based on the in situ generation of Wi ttig salts (alkytri-arylphosphonium bromides) has been developed for t he ring-opening polymerization of cyclic bisphenol-A (BPA) carbonate o ligomers for potential use in composite applications so that the prepo lymer can suitably wet the composite material before being converted t o high molecular weight polymer. The Wittig salt precursors (an alkyl bromide, such as hexadecyl bromide, and a triarylphosphine, such as tr iphenylphosphine) did not independently initiate significant ring-open ing polymerization of the oligomeric cyclic BPA carbonate mixture. How ever, when the two mixtures of cyclic BPA carbonate oligomers and init iator component were combined, a high molecular weight polymer (M(w) = similar to 65,000) was produced. The polymerization initiating specie s is thought to be hexadecyltriphenyl-phosphonium bromide. Consistent with this hypothesis is the observation that authentic Wittig salts di d initiate ring-opening polymerization to provide high molecular weigh t polycarbonate. The effects of structure and concentration of the ini tiator components, reaction temperature, time, etc. on polymerization were studied; in general, the degree of polymerization ranged from 65 to 85%. (C) 1996 John Wiley & Sons, Inc.