Block copolymers by transformation of living ring opening polymerization into an initer process

The transformation of ring opening polymerization into an initer process is reported for the preparation of the block copolymer of ε-caprolactone (CL) with styrene (St). In the first step, ring opening polymerization of CL was carried out by using triphenyl methanol (TPM) as the initiator and aluminum alkoxide as the promoter, respectively, to give a triphenylmethyl (trityl)-terminated polymer. UV and ¹H-NMR studies show that the trityl group associated with the active alkoxy group of the initiator is selectively attached to one chain end. In the second step, the trityl-terminated polymer served as a thermal 'initer' for the polymerization of styrene and this makes it possible to prepare a block copolymer.