Shape memory quasi-liquid slippery surface

Abstract

Shape memory droplet manipulation platforms have garnered widespread attention due to their programmable droplet control capabilities. Current research primarily focuses on superhydrophobic surfaces and slippery lubricant-infused porous surfaces (SLIPS); however, vulnerable surface micro/nanostructures and loss of lubricant oils are unavoidable. Herein, we report a shape memory quasi-liquid polydimethylsiloxane (PDMS) brush surface that can avoid the above imperfections. The surface was prepared by introducing a layer of SiO₂ as a “bridge” on a shape memory epoxy substrate to provide abundant functional active groups for grafting PDMS brushes. By precisely controlling the thickness of the SiO₂ layer and the grafting condition of the PDMS brushes, the obtained surface shows good shape memory property and low adhesion to diverse liquids with different surface tensions. Reversible anisotropic/isotropic droplets sliding control for both water and organic droplets was demonstrated through dynamic introduction/removal of the groove structures on the surface, proving the excellent droplet manipulation function based on the combination of shape memory property and the low adhesion of the PDMS brushes. Furthermore, the obtained material can be used as a functional coating for diverse substrates to impart anti-fouling and self-cleaning properties. This work proposed the use of a nanoscale SiO₂ layer as a “bridge”, which offers a strategy to address the challenge of grafting PDMS brushes onto a polymer surface. Meanwhile, given the excellent advantages of quasi-liquid PDMS brushes and programmable controllability of shape memory polymer, this work could provide some fresh ideas for the development of a droplet manipulation platform.