Shape Memory Quasi-Liquid Slippery Surface for Programmable Droplet Manipulation
Shape memory droplet manipulation platforms have attracted significant attention due to their programmable droplet control capabilities. Current research primarily focuses on superhydrophobic surfaces and slippery lubricant-infused porous surfaces (SLIPS); however, these approaches suffer from vulnerable surface micro/nanostructures and loss of lubricant oils. Here, we report a shape memory quasi-liquid polydimethylsiloxane (PDMS) brush surface that overcomes these limitations. The surface is fabricated by introducing a SiO2 layer as a 'bridge' on a shape memory epoxy substrate, providing abundant functional groups for grafting PDMS brushes. By precisely controlling the SiO2 layer thickness and grafting conditions, the surface exhibits good shape memory properties and low adhesion to diverse liquids with varying surface tensions. Reversible anisotropic/isotropic droplet sliding control for both water and organic droplets is demonstrated through dynamic introduction/removal of groove structures, proving excellent droplet manipulation based on the combination of shape memory and low adhesion of PDMS brushes. Furthermore, the material can be applied as a functional coating on diverse substrates to impart anti-fouling and self-cleaning properties. This work introduces a nanoscale SiO2 layer as a 'bridge', offering a strategy to graft PDMS brushes onto polymer surfaces. Given the advantages of quasi-liquid PDMS brushes and programmable controllability of shape memory polymers, this work provides fresh ideas for developing droplet manipulation platforms.