Synthesis of triblock copolymers via metathetic degradation of poly-butadiene combined with ring-opening polymerization of D,l-lactide

Controlled degradation of polymers and tandem living polymerization methodology offer astonishing opportunities to recombine different kinds of polymers and monomers into valuable, well-defined copolymers with excellent properties and wide application prospects. In this work, the possibility of synthesizing ABA triblock copolymers by combining cross metathetic degradation of poly-butadiene (PB) with ring-opening polymerization of d,l-lactide was studied and confirmed. The effects of the reaction time and the concentration of the chain transfer agent (CTA) on the final molecular weights of the telechelic polymers were investigated. As a result, a new and high valuable α,ω-diol-ended PB (macro-CTA) was synthesized by the metathetic degradation of PB with acyclic olefin (cis-1,4-diacetoxy-2-butene) as the CTA, which was then hydrolyzed. With Sn(Oct)2 as the catalyst, the reaction of difunctional macro-CTA with d,l-lactide was successfully realized and series of well-defined ABA triblock copolymers with different molecular weights were achieved.