Synthesis and Characterization of Polyimides Based on Twisted Non-coplanar Backbone Containing Indolocarbazole

A diamine monomer(4,4’-(((5,11-dihydroindolo[3,2-b]carbazole-6,12-diyl)bis(4,1-phenylene))bis(oxy))dianiline) containing a rigid conjugated indolocarbazole was designed and synthesized through a three-step reaction. A series of high-performance functional polyimides were prepared through simple condensation polymerization of the monomer with different industrial dianhydrides 6 FDA, BTDA and ODPA,respectively, which exhibit superior thermal stability, good solubility in polar organic solvents and good mechanical properties. The glass transition temperature(T) is above 334℃, and the 5% weight loss temperature(T5%) of polyimides under nitrogen atmosphere falls in the range of 502～526℃. The tensile strength and tensile modulus are 49.45～60.08 MPa and 1.4～1.6 GPa, respectively. In addition, the maximum fluorescence emission wavelength of polyimides in the NMP solution(0.02 mg/mL) are around 448 nm with blue light emission and 451 nm as film without significant red shift, which indicates the prepared polyimides process a certain application potential in high-performance flexible polymer optoelectronic devices.