多孔/层状阶层结构铝超疏水表面润湿转换机制及抗腐蚀行为研究

Superhdrophobic aluminum/aluminum alloy surfaces of Cassie state have a broad application prospect in the field of marine corrosion and protection. However, the Cassie state is easily damaged and irreversibly transferred into Wenzel state during anticorrosion process, leading to the degradation of hydrophobicity and anticorrosion ability, which is indicated as the key issue that restricts the application of superhydrophobic aluminum/aluminum alloy surfaces in marine environment. In this work, porous anodic alumina (PAA) will be fabricated on aluminum substrate through an anodic oxidation process, and hierarchical structure will be achieved by in-situ growth of Layered double hydroxide films on the walls of PAA pores with the aims of increasing the energy barrier against the transition of wetting state and the mechanical durability of superhdrophobic surface. Meantime, polydopamine (PDA) of high adhesivity and abundant groups will be introduced to bridge the hierarchical structure and the surface hydrophobic layer in order to improve the chemical stability of the surface hydrophobic layer and reduces the surface chemical inhomogeneity for further improving the stability of Cassie state and the anticorrosion performance. Based on the characterization and investigation on the contact angle and electrochemical performance of superhydrophobic surfaces, the influences of PAA/LDH hierarchical structure, surface hydrophobic layer on the stability of Cassie state and the corrosion resistance of the superhydrophobic surface will be revealed, and the wetting transition and anticorrosion mechanisms of superhydrophobic surface will be improved in the mean time, which will provide theoretical basis for the fabrication of superhydrophobic aluminum based surfaces with ultra-high anticorrosion performance.

Cassie型铝及铝合金超疏水表面在海洋腐蚀与防护领域有广阔的应用前景。然而，在抗腐蚀过程中，Cassie界面易被破坏并不可逆转地过渡到Wenzel界面，导致表面疏水性及相应抗腐蚀性能的退化，是制约铝及铝合金超疏水表面在海洋环境中应用的关键问题。本项目拟采用阳极氧化技术在铝表面构建多孔氧化铝（PAA），并在PAA孔壁原位生长层状双金属氢氧化物（LDH）分级粗糙结构，以提高超疏水表面润湿转换能量势垒和机械稳定性。同时，在粗糙结构和表面疏水改性层之间引入粘附性强、官能团丰富的聚多巴胺（PDA），提高表面疏水改性层的化学稳定性和化学组成均一性, 进一步提高Cassie界面稳定性和表面抗腐蚀性能。通过对超疏水表面进行接触角和电化学表征，揭示PAA/LDH阶层结构、表面疏水改性层与Cassie界面稳定性和表面抗腐蚀性能之间的构效关系，完善超疏水表面润湿转换和抗腐蚀理论，为构建具有优异抗腐蚀性能的铝基超疏水表面提供科学依据。

Cassie型超疏水表面粗糙结构中俘获的气体能有效阻止侵袭性Cl- 离子及液体与固体表面的接触，阻止腐蚀反应发生，提高表面抗腐蚀性能，受到研究人员的广泛关注。抗腐蚀过程中，Cassie界面容易发生不可逆转的破坏，降低表面抗腐蚀性能，成为制约超疏水表面在腐蚀防护领域应用的关键问题。本项目通过二次阳极氧化技术在铝基表面构建封闭多孔结构（PAA）来降低滞留空气的逃逸速度问题，通过在PAA表面原位构建层状LDHs阶层粗糙结构及原位引入聚多巴胺（PDA）表面改性层来提高表面疏水稳定性和抗腐蚀性能。结果显示，具有层状阶层结构的PDA辅助超疏水改性LDHs/PAA表面疏水角可达160°以上，迟滞角小于5°，表现出优异的疏水稳定性和抗腐蚀性能。分析认为原位生长PAA多孔结构、原位生长LDHs分级阶层粗糙结构极大地提高了表面疏水稳定性，同时协同LDHs层状阶层结构捕获Cl-离子的能力进一步提高了表面抗腐蚀性能。研究结果对推进铝基超疏水抗腐蚀表面在工业领域尤其在海洋腐蚀防护领域应用具有重要理论指导价值。