Synthesis and properties of poly(imide siloxane) block copolymers with different block lengths

Several poly(imide siloxane) block copolymers with the same bis(-aminopropyl)polydimethylsiloxane (APPS) content were prepared. The polyimide hard block was composed of 4,4-oxydianiline and 3,3,4,4-diphenylthioether dianhydride (TDPA), and the polysiloxane soft block was composed of APPS and TDPA. The length of polysiloxane soft block increased simultaneously with increasing the length of polyimide hard block. For better understanding the structure-property relations, the corresponding randomly segmented poly(imide siloxane) copolymer was also prepared. These copolymers were characterized by FT-IR, 1H-NMR, dynamic mechanical thermal analysis, thermogravimetric analysis, polarized optical microscope, rheology and tensile test. Two glass transition temperatures (Tg) were found in the randomly segmented copolymer, while three Tgs were found in the block copolymers. In addition, the Tgs, storage modulus, tensile modulus, solubility, elastic recovery, surface morphology and complex viscosity of the copolymers varied regularly with increasing the lengths of both blocks. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013