Ezazi Mohammadamin, Shrestha Bishwash, Maharjan Anjana, Kwon Gibum
Department of Mechanical Engineering, University of Kansas, Lawrence, Kansas 66045, United States.
ACS Mater Au. 2021 Oct 13;2(1):55-62. doi: 10.1021/acsmaterialsau.1c00036. eCollection 2022 Jan 12.
Superomniphobic surfaces that can self-repair physical damage are desirable for sustainable performance over time in many practical applications that include self-cleaning, corrosion resistance, and protective gears. However, fabricating such self-repairing superomniphobic surfaces has thus far been a challenge because it necessitates the regeneration of both low-surface-energy materials and hierarchical topography. Herein, a water-responsive self-repairing superomniphobic film is reported by utilizing cross-linked hydroxypropyl cellulose (HPC) composited with silica (SiO) nanoparticles (HPC-SiO) that is treated with a low-surface-energy perfluorosilane. The film can repair physical damage (e.g., a scratch) in approximately 10 s by regenerating its hierarchical topography and low-surface-energy material upon the application of water vapor. The repaired region shows an almost complete recovery of its inherent superomniphobic wettability and mechanical hardness. The repairing process is driven by the reversible hydrogen bond between the hydroxyl (-OH) groups which can be dissociated upon exposure to water vapor. This results in a viscous flow of the HPC-SiO film into the damaged region. A mathematical model composed of viscosity and surface tension of the HPC-SiO film can describe the experimentally measured viscous flow with reasonable accuracy. Finally, we demonstrate that the superomniphobic HPC-SiO film can repair physical damage by a water droplet pinned on a damaged area or by sequential rolling water droplets.
在许多实际应用中，包括自清洁、耐腐蚀和防护装备等，能够自我修复物理损伤的超疏液表面对于长期可持续性能而言是非常理想的。然而，制造这种自修复超疏液表面迄今为止一直是一项挑战，因为这需要同时再生低表面能材料和分级形貌。在此，通过利用与二氧化硅（SiO）纳米颗粒复合的交联羟丙基纤维素（HPC）（HPC-SiO）并经低表面能全氟硅烷处理，报道了一种水响应性自修复超疏液薄膜。该薄膜在施加水蒸气时，通过再生其分级形貌和低表面能材料，能够在大约10秒内修复物理损伤（例如划痕）。修复后的区域显示出其固有的超疏液润湿性和机械硬度几乎完全恢复。修复过程由羟基（-OH）基团之间的可逆氢键驱动，该氢键在暴露于水蒸气时会解离。这导致HPC-SiO薄膜向受损区域发生粘性流动。由HPC-SiO薄膜的粘度和表面张力组成的数学模型能够以合理的精度描述实验测量的粘性流动。最后，我们证明超疏液HPC-SiO薄膜可以通过固定在受损区域的水滴或连续滚动的水滴来修复物理损伤。
