Abstract: The study of thermal behavior of the crystalline polymer ultra-thin films was carried out in this paper. We focused on the effect of the thickness of the ultra-thin films on the melting temperature T_m and the crystallization temperature T_c. The ultra-thin films were made by means of spin-coater. The thicknesses of the films vary from about 20 nm to over 1 500 nm. The T_m and T_c of the ultra-thin films were measured by using differential scanning calorimetry(DSC). The results show that with the decrease of the film thickness, the T_m of PHB thin films first decrease gradually and then rise dramatically in a specific range, finally with further decreases of film thickness T_m decrease again sharply and the crystallization temperature T_c descended. The thermal behavior of the thickness of the ultra-thin films is discussed under a restrained condition.

Key words: Polymer ultra-thin film, Thickness, Melting point, Crystallization temperature