Synthesis and Characterization of Conjugated Polymer Containing Benzophenanthrene Liquid Crystal Unit in Side Chain

In this paper, a side chain conjugated polymer PBTTPHT-C8 containing benzophenanthrene discotic mesogens was designed and synthesized. Through the catalysis of anhydrous ferric chloride, 1,2-benzenedioctyl ether and 2-bromophenoxyphene ether undergo an intermolecular ring-forming reaction to synthesize side-chain benzophenanthrene discotic liquid crystal unit; In the condition of anhydrous and argon protection, the target polymer was synthesized by Stille cross-coupling reaction between 2,5-dibromo-3-benzophenanthrophene and 4,7-bis(trimethyltin)-2,1,3-benzothiadiazole. The structure of the synthesized monomers and polymers were characterized using advanced Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR). Gel permeation chromatograph (GPC) was used to characterize the molecular weight of the polymer. The UV visible spectrophotometer (UV-vis) test shows that the polymer has absorption peaks at 243 nm and 399 nm, and the band gap is 2.21 eV. Cyclic voltammetry (CV) tests show that the polymer E_HOMO is −5.62 eV and E_LUMO is −3.41 eV.