Synthesis and characterization of diblock and triblock copolymer by enzymatic ring-opening polymerization of epsilon-caprolactone and ATRP of styrene

摘要

Diblock and triblock copolymer of epsilon-caprolactone(epsilon-CL) and styrene( St) were obtained by the combination of two different polymerization process, namely enzymatic ring-opening polymerization(ROP) and atom transfer radical polymerization( ATRP) methods. Mono-/ di- hydroxyl terminated macromolecules were prepared by enzymatic ROP of epsilon-CL in the presence of Novozyme-435 and methanol/ethylene glycol as biocatalyst and initiator, respectively, and subsequently converted to bromine ended polycaprolactone(PCL) by the esterification of the resulting macromolecules with alpha-bromopropionyl bromide. The mono- and difunctional macroinitiators were employed in ATRP of styrene using CuCl/2,2'-bipyridine( bpy) as the catalyst system. The GPC and H-1-NMR analysis indicated a controlled/living radical polymerization which resulted in the formation of block copolymers with narrow polydispersities.