Unlocking of interlocked heteropolymer gel by light: photoinduced volume phase transition in an ionic liquid from a metastable state to an equilibrium phaseElectronic supplementary information (ESI) available: Experimental procedures (chemicals, apparatus, synthetic procedure for gels), the reversibility of volume phase transition in P(trans-AzoMA-r-BnMA) gel, redissolution kinetics of linear polymers, and estimation of azobenzene separation. See DOI: 10.1039/c2cc30830d

An azobenzene-containing heteropolymer gel in an ionic liquid exhibits thermally reversible volume phase transition when the azobenzene moiety mainly exists in the cis -state, whereas the transition becomes irreversible when it is in the trans -state and an interlocked collapsed state is stabilized; however, the unlocking of the metastable state occurs by UV light irradiation. An azobenzene(AB)-containing gel in an ionic liquid exhibits thermally irreversible volume phase transition when the AB exists in the trans -state; however, the unlocking of an interlocked state occurs by UV light irradiation.