Well-Defined Amphiphilic Biodegradable Comb-Like Graft Copolymers: Their Unique Architecture-Determined LCST and UCST Thermoresponsivity

Abstract

As an extremely promising characteristic, the transformation between a lower critical solution temperature (LCST) and an upper critical solution temperature (UCST) has rarely been reported until now. In the present paper, a three-step strategy, based on “grafting onto” concept, was implemented to synthesize a novel thermoresponsive amphiphilic biodegradable and biocompatible poly(p-dioxanone)-grafted poly(vinyl alcohol) (PVA-g-PPDO) copolymer with well-define structure. A transformable thermoresponsivity from a LCST to an UCST can be achieved facilely via changing the graft chain length of the resulting PVA-g-PPDO copolymers. The results of transmittance indicate that a wide range of LCST and UCST between 30 and 80 °C can be achieved easily, which is attributed to the controllable structures and hydrophobic/hydrophilic ratio of copolymers by adjusting degree of polymerization (Dp) of PPDO prepolymers and molar feed ratios in the last esterification coupling step. This is the first example having the featu...