Phenylethynyl End-capped Polyimide Oligomers Derived from BTDA

A diamine monomer\2,5-bis(4-aminophenoxy)biphenyl(p-TPEQ)was synthesized by four-step routes, and 4-(1-phenyl ethynyl)-1,8-naphthalic anhydride(PENA) was synthesized and characterized as well. Two series of phenylethynyl-terminated imide oligomers were prepared by reacting BTDA with p-TPEQ, and end-capped with 4-phenylethynylphthalic anhydride(PEPA) or PENA. The thermal curing processes of the oligomers were investigated by FTIR, differential scanning calorimetry. As a result of undergoing a complex reaction of the phenylethynyl in the heating run, T_g increased with the increase of content of phenylethynyl. The obtained imide oligomers were molded into films. The cured films exhibited excellent mechanical properties and thermo-oxidative stability. All the results indicate that the incorporation of p-TPEQ monomer can increase the solubility and processing ability of the oligomers.