This month in Journal of Polymer Science A, Kazuo Akagi from Kyoto University in Japan highlights some of the recent advances made in the field of liquid-crystal conjugated polymers, focusing on those that are ferroelectric and photoresponsive. Poly(para-phenylene) and poly(meta-phenylene) derivatives display chiral smectic C phases, which are responsible for ferroelectricity; they have been found to have a high electric-field response, showing switch-ing times of less than one second between two bistable states. The spontaneous polarization of poly(meta-phenylene) remains unchanged even after the electric field is zero, which has potential in liquid-crystal-based memory functions. When dithienylethene moieties are introduced into the side chains of photoresponsive poly(para-phenylenevinylene) and poly(bithienylene-phenylene) derivatives, they are found to exhibit drastic quenching of fluorescence when the photoresponsive moiety changes from an open form to a closed one upon irradiation of ultraviolet light. The quenched fluorescence is recovered through photoisomerization from the closed form back to the open one.

K. Akagi et al., J. Polym. Sci., Part A: Polym. Chem. ; DOI: 10.1002/pola.23277