Structures and Properties of Side-Chain Cholesteric Liquid Crystalline Polyacrylates

The synthesis and mesomorphic properties of four monomers and three side-chain cholesteric liquid crystalline polymers containing 4-cholesteryl-4’-(acryloyloxy-n-alkyloxy)benzoate mesogenic side groups are described. The structure-property relationships of monomers M-1–M-4 and polymers P-1–P-3 are discussed. Phase behavior and optical properties were investigated by differential scanning calorimetry, thermogravimetric analyses, and polarizing optical microscopy. Monomers M-1–M-4 and polymers P-1–P-3 revealed cholesteric phase. Cholesteric texture and reflection color of the polymers were frozen by quenching. The experimental results demonstrated that selective reflection of M-1–M-4 and P-1–P-3 shifted to the long wavelength region with rigidity of the mesogen or decrease of flexible spacer length. Polymers with flexible spacer showed lower phase transition temperatures, wider mesomorphic temperature ranges and higher thermal stability compared with the polymer with no flexible spacer.