Poly(ε-caprolactone)−Poly(fluoroalkylene oxide)−Poly(ε-caprolactone) Block Copolymers. 1. Synthesis and Molecular Characterization

Abstract

Hydroxyl-terminated telechelic poly(fluoroalkylene oxide)s, (PFPE)s, with molecular weights ranging from 1100 to 3400 were employed as transfer agents for the ring-opening polymerization of epsilon-caprolactone (CL) in the presence of various catalysts/initiators. The highest conversion rate of CL was observed using Ti(OBu)(4) and Bu2SnO as catalysts/initiators. The polymerization of CL started only from the hydroxyl groups of PFPE, leading to the formation of ABA triblock copolymers without formation of homopolymer poly(epsilon-caprolactone) (PCL). The rate of insertion of the first unit of CL is much faster than the insertion of the other CL units, and the average molecular weight of the ABA copolymers was that expected by the CL/PFPE ratio. The polymerization rate of CL in the presence of PFPE using aluminum alkoxides as initiator was very slow, contrary to what is known about the homopolymerization of CL.