Synthesis of Thermotropic Polyurethanes Containing Biphenylnate and Imide Units and their Mesophase Behavior
A series of novel liquid crystal polyurethanes containing biphenylnate and imide units were synthesized through the polyaddition reaction of 4,4′-Bis-(2-hydroxyhexoxy)biphenyl (BP2), 2,4-toluenediisocyanate (2,4-TDI) with N,N′-bis(2-hydroxyhexyl)-dicarboxyimide (BHDI) by altering the molar ratio of BP2 and BHDI. The effects of structure difference molar ratio between BP2 and BHDI on the liquid crystalline behavior and thermal stability were studied. Results showed that all of the polyurethane polymers exhibited thermotropic nematic liquid crystalline textures in the range of 160~190°C. The melting temperatures (Tm) and the thermal stability increased with increasing BHDI content.
Huaiying Zhou, Tianlong Gu, Daoguo Yang, Zhengyi Jiang, Jianmin Zeng
Z. Y. Huang et al., "Synthesis of Thermotropic Polyurethanes Containing Biphenylnate and Imide Units and their Mesophase Behavior", Advanced Materials Research, Vols. 197-198, pp. 1332-1336, 2011