Enzymatic degradation of fluorinated Poly(ε-caprolactone) (PCL) block copolymer films with improved hydrophobicity

Abstract

Fluorinated Poly(ε-caprolactone) (PCL) block copolymers PCL-PTFOA(2 h), PCL-PTFOA(4 h), PCL-PTFOA(6 h), PCL-PTFOA(8 h) were prepared via esterification by using poly(1H,1H,2H,2H-perfluorooctylacrylate) (PTFOA) with different molecular weights as reactants. It was found that PCL-PTFOA(6 h) and PCL-PTFOA(8 h) possessed the similar molecular weight via GPC analysis. PCL and fluorinated PCL block copolymers films were prepared by solution casting method. The structure and properties of film surface of the fluorinated PCL block copolymers were analyzed by energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), Differential scanning calorimetry (DSC), water contact angles (WCAs) and the surface free energy. The results showed that the fluorinated PCL films possessed improved hydrophobicity because of the microphase separation between fluoropolymer chain and PCL chain. The enzymatic degradation of PCL, PCL-PTFOA(2 h), PCL-PTFOA(4 h) and PCL-PTFOA(6 h) films were performed at 37 °C in a phosphate buffer solution (PBS, 0.1 M, with a pH of 7.2–7.4) with lipase and analyzed by weight loss, SEM and EDS. It was found that the introduction of fluorine-containing segment reduced the rate of enzymatic degradation of the copolymer film in the early period, while increased the finally weight loss rate with a prolonged time. In addition, the enzymatic degradation rate of PCL-PTFOA(2 h) film and PCL-PTFOA(4 h) film was faster than that of PCL-PTFOA(6 h) film.