A binary polymer blend of side-chain liquid crystalline (SCLC) polymers with azobenzene and cyanobiphenyl side-chains was miscible and formed a compatible polymer blend. The compatible LC polymer blend exhibited the hybrid LC phase with the higher isotropic temperature compared with each homopolymer. X-ray scattering measurement revealed that the hybrid LC blend adopted a highly ordered smectic (Sm) phase such as SmB and SmE phases which the LC homopolymer did not exhibit. We conducted to control the phase-separated state and hybrid LC state of the LC polymer blends through the photoinduced phase transition of the azobenzene photoisomerization by UV irradiation. The LC polymer blends in thin films switched between incompatible (phase-separated) and compatible systems with and without UV irradiation.
