(558j) Solvent Exchange Programs the Lifetime of Soft Information

Autonomous and non-monotonic response behaviors pre-programmed in the temporal domain are ubiquitous in nature. In contrast, response paths of synthetic smart materials are generally monotonic between two equilibrium states and rely on the switch of external stimuli. This paper reports that during the exchange of two solvents, the optical information (opacity) in an elastomer film can autonomously appear-then-vanish in a programmable timeline. A fast small molecular mix driven by osmotic pressure pushes the system far from equilibrium, so phase separation of elastomer/solvents happens, encoding soft information. The vanishing of soft information relies on re-establishing equilibrium, dominated by molecular diffusion through the elastomer-dense phase. The lifetime of encoded soft information can be programmed to be as long as months or as low as hours.