High Performance Biomass-Based Polyimides for Flexible Electronic Applications

Biobased polymers have received extensive research attention in flexible and renewable electronics to meet the concept of environmental sustainability. In this study, we develop a series of new polyimides (PIs) from biosources to serve as the substrate and dielectrics for a flexible organic field-effect transistor (OFET). The bioderived diamine, (3R,6S)-hexahydrofuro[3,2-b]furan-3,6-diyl bis(4-aminobenzoate) (ISBA), synthesized from isosorbide (ISB), was reacted with three dianhydrides of pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA), and cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) to obtain PIs and copolyimides (Co-PIs) with a high biomass content up to 53%. These bioderived PIs possessed high Td's over 400 °C and Tg's over 250 °C. Furthermore, the CBDA-based and PMDA-based PIs exhibited CTE values below 50 ppm K–1 due to the rigid heterocyclic ISB unit and the structural linearity of the CBDA and PMDA moieties in the polymer backbone. High transparency and low coloration were also observed in the biobased PIs. Finally, highly thermal-resistant PI(ISBA-C95B5) consisting of the CBDA/BPDA mole ratio of 95/5 was applied as the substrate and dielectrics in flexible OFET, demonstrating the compatible and stable performance even after being baked at 200 °C for 2 h or 1000 bending cycles. The present study reveals the potential application of biobased PIs in electronic devices for a sustainable economy.