Photoplasticization Effect of an Azobenzene-doped Liquid Crystal Depending on Phase Structures

A photoresponsive plasticizer for a photo-inactive polymer was developed using an azobenzene-doped liquid crystal (LC). The azo-doped LC was miscible with poly(methyl methacrylate) up to a critical concentration, above which it phase-separated from the polymer. A photoinduced decrease in the glass transition temperature (Tg) of the polymer was accomplished by photochemically changing the phase structures of the phase-separated LC; the large decrease in Tg (ΔTg = −23 °C) was obtained with the addition of 70 wt % azo-doped LC.