Interlocking-interface-enabled thermally deformable liquid metal/polymer membrane with high bonding strength

Hypothesis The high surface tension of liquid metal (LM) causes interface incompatibility and poor bonding strength with many substrates. Fine adjustment towards the properties of the surface area is sufficient to introduce strong bonding. Hence, we hypothesize that the interlocking structure using hydrophilic polyvinyl alcohol (PVA) as a “bridge” should be helpful for tight interfacial bonding of LM with polymeric substrates, thus achieving high-performance LM/polymer membranes, which have wide applications in the field of soft sensors and robotics. Experiments The bulk EGaIn was fabricated into LM nanoparticles (LMNPs@PVA) solution. Then, PVA molecules were “doped” into the surface crosslink of the plasma treated polymer substrate by an interfacial penetrating method. Afterward, the solution was evenly dropped on the surface of the treated substrate to obtain the LMNP/polymer membrane after the water evaporated. Photothermal actuators were fabricated based on the membranes. Findings During the interlocking structure, PVA macromolecules could be doped and trapped onto the top surfaces of various polymer substrates as binding “bridges” between the LMNPs and the matrix materials. The achieved LMNP membrane exhibites satisfactory bonding strength, durability and water-assisted erase-reprint, which can be used as soft photothermal actuators with remote laser control.