Coupling of low elastic modulus with porosity makes extreme low ice adhesion strength possible

Anti-icing surfaces are vital for transportation and infrastructure. Low adhesion strength enables energy-efficient wind-driven or vibration-based ice-removal techniques beyond heating. A key challenge is to reduce the tangential adhesion strength of ice below 10 kPa, a goal hindered in practice by the high toughness of the ice-substrate interface. Even superhydrophobic materials with low surface energy struggle. Recent studies leverage low elastic moduli, lubricated surfaces, and minimal ice contact of porous substrates to reduce the adhesion strength. However, the rationale behind such an approach remains unclear, with no theories available for design purposes. In this study, we address this gap by establishing a solid mechanics framework based on fracture mechanics to model ice adhesion and inform anti-icing surface design. Here, we present an ice-solid interface fracture theory based on the Biot theory and a neo-Hookean framework, which accounts for substrate deformation and energy balance during ice debonding. Guided by this model, we optimized material properties of the substrate, including the porosity and pore size. Increasing porosity reduces the contact area and elastic modulus, while an optimized pore size prevents ice ingress and promotes interfacial cracking, lowering the interface toughness and energy cost of ice removal. The model prediction revises conventional scaling relations between the adhesion strength and the substrate modulus by modifying the exponent from 1/2 to 1, allowing the strength to reach even 0.1 kPa in theory. A durable, weather-resistant substrate with a tangential adhesion strength of 3 kPa is demonstrated in experiments.