Stiffening surface lowers ice adhesion strength by stress concentration sites

Abstract

Mechanically softening materials have been intensively investigated to reduce ice adhesion strength based on the adhesion failure mechanism. Achieving icephobic surfaces with both low ice adhesion strength and mechanical robustness is challenging. The surface stiffening-induced stress concentration sites on elastomer should be possible to improve the mechanical robustness and lower the ice adhesion strength simultaneously, as it can build material inhomogeneity (stiffness mismatch) and geometry irregularity-induced cracks on the surface layer of elastic materials. To reveal this hypothesis, the stress concentration sites are introduced to obtain the robust low ice adhesion surface (RLAS) by implementing rigid nanocomposites with the elastic modulus of GPa scales (e.g. silica nanoparticles, SiO2NPs, ca. 68.9 GPa) into the surface layer of elastomers (e.g. polydimethylsiloxane, PDMS, ca. 2.7 MPa). The effects of the material inhomogeneity (stiffness mismatch) and geometry irregularity-induced stress concentration sites on the reduction of ice adhesion strength are revealed. The minimum ice adhesion strength of the RLAS is down to 10.5 kPa, and its ice adhesion strength remains at 13.8 kPa after 25 icing/deicing cycles. Originating from abundant potential crack initiation sites and stiff nanoparticles, our designed nano-composite materials remarkably lower the ice adhesion strength and are over 2-fold mechanically stiffer than pure elastomer. This strategy offers an unconventionally hardening surface approach for designing icephobic materials with combined durability and robustness.