Highly soluble and thermally stable copolyimides modified with trifluoromethyl and siloxane

A series of highly soluble aromatic polyimides with excellent thermal properties were fabricated by traditional two-step polycondensation reaction of dianhydride monomer 4,4-(4,4-isopropylidenediphenoxy)bis(phthalic anhydride) or 4,4-(hexafluoroisopropylidene)diphthalic anhydride with diamine monomer 1,3-bis(4-aminophenoxy)benzene or 1,3-bis(3-aminopropyl) tetramethyldisiloxane in N,N-dimethylacetylamide solvent. Results revealed that copolyimide of PI-4 containing trifluoromethyl and tetramethyldisiloxane possessed excellent solubility and remarkable thermal properties. PI-4 could dissolve well in common low boiling point solvents such as THF of up to 80 mg/mL and acetone of 40 mg/mL. Moreover, the 10% weight loss temperature of the PI-4 was 539C and the T_g value of the PI-4 was 311C. PI-4 might be easily cast into flexible and tough films applied in optoelectronic devices.