Synthesis and properties of hyperbranched polyimides from A2+ B′B2 monomers and A2+ B′B2 + B2 monomers with various comonomer ratios

A series of hyperbranched polyimides were successfully synthesized by A(2) + B'B-2 approach based on 2,4,6-triaminopyrimidine(TAP) and biphenyl dianhydride (BPDA). The resulting polyimides were characterized by FTIR, SEC/MALLS, NMP, DSC, TGA. The results showed that BPDA-TAP hyperbranched polyimides had poor thermal stability. In accord with this fact, difunctional B-2 comonoer (4,4'-oxydianiline(ODA)) was added into the polymer structure to improve heat resisting property of HBPIs by incorporation. This approach could be described as A(2)+ B'B-2 + B-2 or more simply A(2) + B-3 + B-2 copolymerization. Both for the BPDA-TAP-ODA and BPDA-TAP hyperbranched polyimides, the amine-terminated polyimides showed higher glass transition temperature and 10 % weight loss compared with the corresponding anhydride-terminated ones, which can be attributed to the different terminal functional groups and the anhydride residues.