Yeong-Beom Lee, Han Young Woo, Chong-Bok Yoon and Hong-Ku Shim
Nonlinear optical (NLO) functionalized polyimides were directly synthesized using the nitro-displacement reaction between an alkanediol monomer and a diimide monomer without a thermal curing step. The polyimides were soluble in aprotic polar solvents such as DMSO, DMAc, DMF and NMP, and showed glass transitions at temperatures between 172 and 198°C. We observed good thermal stability up to around 300
°C (at 5% weight loss) for the polymers. The weight average molecular weights of the resulting polymers were determined to be 10
400–15
100 (Mw/Mn = 1.84–2.00). The poled polymer films showed good nonlinearity (d33 = 76 pm V–1) in the Maker fringe method for the second harmonic generation (SHG).