Novel rigid semi-alicyclic dianhydride with large side groups for high performance colorless polyimides (CPIs)

A new dianhydride 9,10-diphenyl-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetraacid dianhydride (6FDPDA) with rigid semi-alicyclic structure was reported. CPI materials were prepared by copolymerizing 6FDPDA with 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) or 4,4'-(hexafluoroisopropene) diphthalic anhydride (6FDA) respectively, with 2,2′-bistrifluoromethyl benzidine (TFDB) as the diamine building blocks. Due to the ladder semi-alicyclic structure as well as –CF3 and phenyl large side groups, this new dianhydride exhibits two important advantages, the cut-off conjugated in the polymer backbone and suppressed intermolecular stacking. When 6FDA as the dianhydride comonomer, the obtained CPIs exhibits distinguished performance with transmission of 90 % at 550 nm, YI of 2.45, CTE of 16.5 ppm/K and Tg over 450 °C. These results demonstrated that 6FDPDA is an excellent building block to prepare the high performance CPIs in optoelectronic devices, for an example the substrates for flexible AMOLED display.