Morphology study of a series of azobenzene-containing side-on liquid crystalline triblock copolymers

A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy (TEM), small angle X-rays and neutron scattering (SAXS and SANS) were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies (disordered, lamellar, perforated layer and hexagonal cylinder) were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition (ODT) were studied in situ by SANS.