Synthesis and phase behavior of new cholesteric liquid-crystalline copolymers containing chiral mesogenic groups derived from menthol derivatives

摘要

The synthesis of a new chiral mesogenic monomer (M-1), a nernatic monomer (M-2), and a series of side chain cholesteric copolymers (P-2-P-6) containing the mesogenic menthyl groups is described. The chemical structures of the compounds were confirmed by FTIR and H-1 NMR. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, thermogravimetric analysis, and polarizing optical microscopy. M-1 showed an enantiotropic cholesteric phase, and M-2 revealed a nernatic phase. The homopolymers P-1 and P-7, respectively, displayed a chiral smectic A (S-A) phase and a nernatic phase, while the copolymers P-2-P-6 exhibited the Grandjean texture of the cholesteric phase. T-g, T-i, and Delta T of P-1-P-7 increased with increasing the concentration of M-2 in the polymers. All of the obtained polymers displayed very good thermal stability and the wide mesophase temperature range. (c) 2008 Wiley Periodicals, Inc.