[In-situ study on the crystallization of PCL films using FTIR]

The crystalline behaviors of PCL(poly(epsilon-caprolactone) )thin film on Si and KBr substrates have been studied in-situ using FTIR with a heat stage. In the crystalline process, due to the decrease in free volume and the increase in interaction among different molecules, the peak of C=O shifted to lower wave number and the crystalline peak of C-O-C and C-H appeared. The degree of crystallinity has been calculated through the comparison between the peaks of crystal and amorphous parts. FTIR study on the films cast from solution with different concentrations showed that the thicker the film is, the higher crystallinity it has. This may be due to the substrate effect or geometric confinement. It was also shown that under the same preparation condition, the film on KBr wafer had higher degree of crystallinity than that of film on Si wafer.