Properties, Functions, Chemical Transformation, Nano-, and Hybrid Materials of Poly(diphenylacetylene)s toward Sensor and Actuator Applications

This review examines poly(diphenylacetylene)s (PDPAs) as a special class of conjugated polymers. Various properties of PDPAs, including liquid crystallinity, fluorescence (FL) emission, and chirality are described in detail. The FL origin of PDPAs is intramolecular excimer emission that comes from the intramolecular stack structure of side phenyl rings. PDPAs show remarkable FL responses to external stimuli such as solvents, heat, surface tension, and pressure. PDPAs are easily transformed to desired forms via polymer reactions, chiral solvent annealing, and coupling with long alkyl chains. Very useful nanomaterials and hybrid materials can be prepared by chain quenching and in situ hybridization methods. PDPAs and their nano- and hybrid materials show highly advanced functions toward sensors and actuators.