Study on degradation behaviors of poly(ethylene glycol)/poly(butylene terephthalate) copolymers in a simulated earth environment

The degradable behaviors of a series of block copolymers, based on polyethylene glycol (PEG) as the soft segment and poly(butylene terephthalate)(PBT) as the hard segment, was studied by embedding the copolymer film in a simulating earth environment and immersing film into PBS(pH 7.4) at 37°C. The results show that the copolymer composition affects physical properties, including the swelling ratio, weight loss, inherent viscosity, as well as the micromorphology of copolymer film. The change of inherent viscosity of the copolymers decrease with increasing of PBT content, whereas a relatively lower weight loss occurs in a simulating earth environment, compared with the hydrolytic degradation. Therefore, water could enhance the weight loss of copolymers by facilitating degradation products to disperse into the media. Over a degradation period of 100 days, morphology of copolymer with 30% of PBT mass ratio shows a little change in a simulating earth environment.