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 (T-g) of the polymer was accomplished by photochemically changing the phase structures of the phasese-parated LC; the large decrease in Tg (Delta T-g = -23 degrees C) was obtained with the addition of 70 wt% azo-doped LC.