A thermoresponsive liquid with unique two-way volume memory function

Shape memory materials (SMMs) recover their original shape as an external stimulus is applied. To meet the growing needs for complicated applications, it is imperative to design advanced SMMs with more functions and better performance. This paper reports a new design of liquid-based SMMs, i.e. liquid nanofoam (LN) system, by controlling the extent of liquid outflow from hydrophobic nanopores. The liquid outflow behavior is dominated by the thermoresponsive sensitive bubble nucleation process in the confined nanoenvironment. As temperature increases, the extent of liquid outflow is promoted, and the system volume is recovered. Thus, the LN system exhibits an instant volume memory behavior. As temperature decreases, the volume memory behavior is reversed. A constitutive model for the shape memory LN material has also been developed and validated. The thermoresponsive nanoconfined liquid outflow opens up new avenues for the design of advanced SMM. (paper)