Triblock copolymers composed of soft and semi-crystalline segments—synthesis and characterization of poly[(n-butyl acrylate)-block-(ε-caprolactone)-block-(L-lactide)

Abstract

Poly(n-butyl acrylate) terminated with benzyl alcohol units (PnBA-MI) of varying molecular weights were synthesized by polymerizing n-butyl acrylate using substituted benzyl alcohol based initiators under atom transfer radical polymerization (ATRP) conditions. Between the ligands bipyridine and PMDETA, the latter ligand showed better control for the polymerization of n-BA. High molecular weight diblock copolymers of poly[(n-butyl acrylate)-block-(e-caprolactone)] were synthesized by ring opening polymerization (ROP) of e-caprolactone using PnBA-MI which formed thin, flexible and opaque films which are soft to touch. Triblock copolymers of poly[(n-butyl acrylate)-block-(e-caprolactone)-block-(L-lactide)] were synthesized in a one pot, two step reaction by the sequential addition of monomers. The molecular weights of PCL and PL segments in the triblock copolymers were comparable. Due to this, the triblock copolymer showed exothermic transition upon cooling well above the Tm of PCL block.