Rational design of ionic-liquid infused porous surfaces as liquid repellent coatings

污染物在表面的不受控制的附着会在广泛的技术应用中极大地降低材料的性能，从过滤和膜技术的堵塞到光学设备的视力损失或医疗保健部门的病原体污染。因此，设计驱避性、无污染的表面涂层是一个关键的工程挑战。这个问题的潜在解决方案是从自然界的灵感演变而来的。传统的驱避表面设计模式是莲花植物，它具有超疏水特性，但不能排斥低表面张力的液体或复杂的液体。另一种解决方案受水壶植物的启发，采用渗入多孔表面涂层的流体润滑层。这种润滑剂渗透防止表面与第二个受污染的液体直接接触，从而在液体滑出润滑层时产生有效的排斥力。这种涂层对水、低表面张力液体和复杂流体表现出显著的排斥能力，并具有巨大的潜力，可以防止细菌吸附造成的污垢，减少冰粘附力，并具有自我修复特性，因为流体润滑剂可以回流到表面的受损部分。然而，润滑层可能会蒸发，从而随着时间的推移和温度的升高而降解涂层。在这里，我们的目标是通过使用具有极低蒸汽压的离子液体作为润滑剂来减少润滑剂的损失。为此，我们将首先关注离子液体与表面相互作用的详细分子理解和优化。我们将利用硅烷化学将化学功能引入玻璃模型表面，并测量与离子液体的界面能。我们预计，由于离子液体的化学异质性，可能需要具有多个功能部分的混合自组装单分子膜来最小化界面能量。低界面能是产生稳定的固体-润滑剂界面所必需的，该界面不会被被排斥的液体所取代。其次，我们将创建高度有序的纳米多孔表面(反蛋白石)作为模型涂层，以研究其与离子液体的润湿行为。我们将利用渗透后结构颜色的变化和第二种液体的替换来可视化作为所应用的表面化学的函数的驱避性。然后，我们将把这一概念转化为一种简单且可扩展的涂层工艺。最后，我们将通过将硅烷单分子膜改变为活性酯基聚合物网络的表面结合薄膜来优化长期排斥性能。它们可以被功能胺定量取代，提供模拟离子液体结构元素的侧基，从而最大限度地提高与润滑剂的化学亲和力。

The uncontrolled adhesion of contaminants onto surfaces can drastically decrease the performance of a material in a wide range of technological applications, ranging from clogging in filtration and membrane technology to vision loss in optical devices or pathogen contamination in the healthcare sector. The design of repellent, non-fouling surface coatings is therefore a key engineering challenge.Potential solutions to this problem have evolved from inspiration by the natural world. The traditional role model for the design of repellent surfaces is the Lotus plant, which imparts superhydrophobic properties but can fail to repel low surface tension liquids or complex fluids.An alternative solution is inspired by the Pitcher plant and employs a fluid lubricant layer that is infiltrated into a porous surface coating. This lubricant infiltration prevents direct contact of the surface with a second, contaminated liquid, leading to efficient repellency as the liquid slides off the lubricant layer. Such coatings have shown remarkable repellency of water, low surface tension liquids and complex fluids and great potential for the prevention of fouling by bacteria adsorption, the reduction of ice adhesion, and self-healing characteristics as the fluid lubricant can flow back into damaged parts of the surface. However, the lubricant layer can evaporate, thus degrading the coating over time and at elevated temperatures. Here, we aim to mitigate failure by loss of lubricant using ionic liquids with extremely low vapor pressure as the lubricant. To this end, we will first focus on a detailed, molecular understanding and optimization of the interactions of ionic liquids with the surface. We will use silane chemistry to introduce chemical functionalities onto glass model surfaces and measure the interfacial energy with the ionic liquid. We anticipate that mixed self-assembled monolayers with multiple functional moieties may be required to minimize the interfacial energy, as a consequence of the chemical heterogeneity of ionic liquids. A low interfacial energy is a requirement to create a stable solid-lubricant interface that is not replaced by the liquid to be repelled. Second, we will create highly ordered nanoporous surfaces (inverse opals) as model coatings to investigate the wetting behavior with ionic liquids. We will use the change in structural color upon infiltration and replacement with a second liquid to visualize the repellency properties as a function of the applied surface chemistry. We will then transfer the concept to a simple and scalable coating process. Finally, we will optimize the long-term repellency properties by changing the silane monolayers to surface-bound thin films of active ester-based polymer networks. These can be quantitatively replaced by functional amines, providing side groups that mimic the structural elements of the ionic liquids and thus maximize the chemical affinity with the lubricant.