Heat triggered shape memory behavior of poly(tert-butyl acrylate) based star-block copolymers in physiological range

Abstract

Abstract A series of poly(tert-butyl acrylate) (PtBA) based star-block copolymers were synthesized to obtain physically cross-linked shape memory polymers (SMPs) with body temperature triggering. First, PtBA star polymers were prepared via atom transfer radical polymerization (ATRP) to form the hard segment. Then star polymers were used as macro-initiators (MI) and combined with linear/non-linear derivatives of poly(ethylene glycol) (PEG), which build the soft segment. Characteristics of star-block copolymers were controlled by fraction, molecular weight and topology of the soft segment. Copolymers were prepared with varying soft segment ratio from 5.3 to 55.4 wt% and Tm of soft segment is adjusted between 28.9 and 55.6 °C. PtBA based copolymers with enhanced hydrophilicity (from 86.3 to 57.6°) exhibited Tm based shape memory behavior around body temperature with good shape recovery (Rr = 98.5%) and shape fixity (Rf = 98%).