| 초록 |
A series of thermotropic polyurethanes containing biphenyl units was synthesized by the polyaddition reaction of diisocyanates such as 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), hexamethylene diisocyanate (HDI) with 4,4'-Bis(9-hydroxynonoxy)biphenyl (BP9). 4,4'-bis(9-hydroxynonoxy)biphenyl exhibited a smectic type mesophase. Mesophase was found for all synthesized liquid crystalline polyurethanes except 1,4-PDI/BP9. The structures of the monomer and the corresponding polymers were identified by using FT-IR and 1H NMR spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry (DSC) and optical polarizing microscopy. |
