Zhao Tom Y, Jones Paul R, Patankar Neelesh A
Northwestern University, Department of Mechanical Engineering, 2145 Sheridan Road, Evanston, Illinois, 60208, United States.
Sci Rep. 2019 Jan 22;9(1):258. doi: 10.1038/s41598-018-36268-5.
The build-up of ice on aircraft, bridges, oil rigs, wind turbines, electrical lines, and other surfaces exposed to cold environments diminishes their safe and effective operation. To engineer robust surfaces that reduce ice adhesion, it is necessary to understand the physics of what makes a surface icephobic ("ice-hating") as well as the relationship between icephobicity and ice adhesion. Here we elucidate the molecular origin of icephobicity based on ice-surface interactions and characterize the correlation between material icephobicity and liquid wettability. This fundamental understanding of icephobic characteristics enables us to propose a robust design for topologically textured, icephobic surfaces. The design identifies the critical confinement length scale to sustain liquid water (as opposed to ice) in between roughness features and can reduce the strength of ice adhesion by over a factor of twenty-seven compared to traditional hydrophobic surfaces. The reduction in ice adhesion is due to the metastability of liquid water; as ambient ice cleaves from the textured surface, liquid water leaves confinement and freezes - a process which takes the system from a local energy minimum to a global energy minimum. This phase transition generates a detachment force that actively propels ambient ice from the surface.
飞机、桥梁、石油钻井平台、风力涡轮机、电线以及其他暴露在寒冷环境中的表面上结冰，会削弱其安全有效运行。为了设计出能降低冰附着力的坚固表面，有必要了解使表面具有憎冰性（“憎冰”）的物理原理以及憎冰性与冰附着力之间的关系。在此，我们基于冰 - 表面相互作用阐明了憎冰性的分子起源，并表征了材料憎冰性与液体润湿性之间的相关性。对憎冰特性的这种基本理解使我们能够提出一种用于拓扑纹理化憎冰表面的稳健设计。该设计确定了在粗糙度特征之间维持液态水（而非冰）的临界限制长度尺度，与传统疏水表面相比，可将冰附着力的强度降低超过27倍。冰附着力的降低归因于液态水的亚稳性；当环境中的冰从纹理化表面分离时，液态水离开限制区域并冻结——这一过程使系统从局部能量最小值转变为全局能量最小值。这种相变产生了一个分离力，该力主动将环境中的冰从表面推开。
