Programmable Chromism and Photoluminescence of Spiropyran-Based Liquid Crystalline Polymer with Tunable Glass Transition Temperature.

Spiropyran-based materials (SPBMs) can give responses to the stimulations induced by the light, heat, force, or pH, which have been used as triggers for many smart materials. Here, a cross-linkable SPBM containing mesogenic-units is synthesized, which is pale-colored, non-photoluminescent and non-mesogenic at a spiro form, but dark-colored, photoluminescent, and mesogenic at a merocyanine form. Moreover, the dynamic interconversion behavior of the form in the different chemical environments are distinct. Liquid crystalline polymers (LCPs) containing the SPBMs cross-linked via visible light, own a photoswitchable glass transition temperature (T ) and retain the switchable property; however, the SPBMs cross-linked via UV light will be locked at the MC state, because the molecular movement was frozen at the room temperature lower than the given T of the LCP. Thus, programmable chromism and photoluminescence based on the tunable T can be endowed to the functional materials prepared from the SPBMs.