Synthesis and characterization of adamantane-based copolyimides with high transparency

In this work, a copolyimide (Co-PI) film with high transparency was prepared by the copolymerization of hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3 ′ ,4,4 ′ -biphenyltetracarboxylic dianhydride (BPDA), 2,2 ′ -Bis(trifluoromethyl)benzidine (TFMB) and adamantane-1,3-diamine (DAA). The effects of DAA monomers on the optical, thermal, and mechanical properties of the co-PIs were discussed in detail. We found that the preparation of polyimide (PI) based on the combination of two dianhydrides and two diamines could obtain the co-PI film with excellent comprehensive performance due to the synergy between the -CF 3 group, the aliphatic ring and the aromatic structure. Through the structure and composition optimization, the co-PI film with 1.30% DAA (Q3) has a T g of 374 o C, T 5 higher than 530 o C, T 430 of 82% and the tensile strength higher than 145 MPa. These results indicate that the Co-PI films can be successfully utilized in the development of novel heat-resistant plastic substrates for the optoelectronic engineering applications.