Rationally Regulating the Mechanical Performance of Porous PDMS Coatings for the Enhanced Icephobicity toward Large-Scale Ice.

Ice accumulation on various surfaces in low-temperature and high-humidity environments is still a major challenge for several engineering applications. Herein, we fabricated a kind of PDMS coating with the introduction of porous structures under the surface by a two-step curing and phase separation method. The coatings with no further surface modification showed good hydrophobicity and icephobicity, and the typical ice adhesion strength was down to 40 kPa with a water contact angle of 116.5°. More than that, the porous PDMS coatings showed extraordinary icephobicity, especially toward large-scale ice (>10 cm). In this case, the large-scale ice layer can be rapidly removed under a small external deicing force in a form of interface crack propagation rather than whole direct fracture. It was confirmed that by regulating the pore size and porosity of PDMS coatings properly, the stiffness mismatch between coatings and ice can be controlled to induce the initiation of interfacial cracks. On this basis, under the condition of a large-scale icing area, a small external deicing force can cause an increased surface stress concentration, and the formed interface cracks can propagate quickly, resulting in the ice layer falling off easily. In addition, under the influence of the size effect, ice can be removed without an additional force, and the minimum external force (per unit width) can be only 60 N/cm. This paper proposes that prefabricating a large number of microcracks at the interface can significantly weaken the bonding between ice and coatings, that is, reduce the fracture toughness. The new coatings have a remarkable effect toward large-scale icing.