Abstract
Some liquid crystalline copolymers were prepared by radical polymerization of mesogenic monomers having cyanobiphenyl, carboxybiphenyl, and cholesterol groups with acrylic acid (AA). AA enhanced the liquid crystalline ordering and the isotropic temperature. The copolymers were easily oriented by spinning in the liquid crystalline melt to yield the fibrous samples. When the fibers were immersed into the water, the molecularly-oriented hydrogels were successfully created. The hydrogels showed a phase transition from a smectic A (SmA) to a smectic I (SmI) by increasing the water content. When the SmI hydrogels were mechanically elongated, an inverse SmI-SmA transition was observed. Moreover, the SmI-SmA transition occurred at 40°C upon heating. A large shrinkage in the oriented hydrogels was observed through the thermotropic SmI-SmA transition in the body temperature range in water. We expected that the liquid crystalline hydrogel system may lead to a possible artificial muscle for biomedical uses in the future.
