| 초록 |
A series of novel polyurethanes was synthesized by the polyaddition reaction of diisocyanates: 2,6-tolylene diisocyanate (2,6-TDI), 2,5-tolylene diisocyanate (2,5-TDI), 2,4-tolylene diisocyanate (2,4-TDI), and 1,4-phenylene diisocyanate (1,4-PDI) reacted with 4,4'-bis(7-hydroxyheptoxy)biphenyl (BP7) which exhibits a smectic type mesophase. All synthesized liquid crystalline polyurethanes except 1,4PDI/BP7 exhibit liquid crystalline behavior. Polyurethanes exhibit nematic liquid cystalline texure which is detected at the cooling run from the isotropic state under the shear but not at the heating run. |
