Surfaces With Special Wettability: Fabrication And Investigation Of Self-healing Performance

Wettability is one of important surface properties of solid materials, and it is also one kind of interfacial phenomena existed widely in nature. According to the wetting theories, contact angle（CA） is used as physical parameter to evaluate surface wettability. According to the evaluation criterion, surfaces with water（or oil） contact angle approaching to 0° can be considered as superhydrophilic（or superoleophilic） surfaces, while those with water（or oil） contact angle greater than 150° can be considered as superhydrophobic（or superoleophobic） surfaces. Hence, surfaces with extremely liquid repellency or liquid spreading are called as special wetting surfaces.Inspired by natural surfaces with special wettability like lotus leaves, strider legs, butterfly wings and mosquito compound eyes, biomimetic special wetting surfaces especially superhydrophobic and superamphiphobic surfaces have been studied widely owing to their wide range of potential applications in self-cleaning, anti-fouling, drag reduction, anti-fogging, anti-icing, corrosion resistance, oil-water separation, and so on. However, special wetting surfaces are difficult to fabricate since they requires both well-designed topography structures and chemical surface modification with low-surface energy agents. In the present research, most works have adopted complex methods including multi-steps to complete the fabrication of special wetting materials. Therefore, it should explore a simpler way like in-situ deposition to fabricate superhydrophobic and superamphiphobic materials. Moreover, the applications of these materials in practice are limited by the low mechanical durability and chemical stability, since generally their surfaces are in the metastable state and the surface structure and chemistry are liable to damage. Inspired by the nature, some works have reported functional surfaces with self-healing ability. Therefore, robustness should be realized through endowing the special wetting surfaces with self-healing performance. Therefore, it is an urgent requirement to fabricate surfaces with special wettability using simple and effective method and realize high mechanical durability and chemical stability using excellent self-healing performance.In order to put forward a facile and effective method of fabricating biomimetic surfaces with special wettability and realize their self-healing performance, this dissertation has carried out a series of research work including the design, fabrication, characterization and application of superhydrophobic and superamphiphobic surfaces. Moreover, it has also studied the self-healing performance of superhydrophobic and superamphiphobic surfaces induced by temperature, mechanical force and near-infrared（NIR） light, respectively. The main contents and results about this dissertation are summarized as follows:1. Based on Schiff base reaction between PDA and ODA, PDA@ODA nanocapsules were prepared using interfacial polymerization method. Simultaneously, PDA@ODA nanocapsules were in-situ deposited on the surface of textiles and hence endowed the fabric surface with hydrophobicity. The modified fabric showed a considerable increase in its liquid repellency due to the synergistic effect of the micro-nano hierarchical structures provided by nanocapsules and microfibers and the low surface free energy of ODA. The modified fabric also showed self-healing performance induced by heating because ODA loaded in PDA capsules melted and released from capsules via temperature increasing. Thanks to the self-healing ability and the versatile adhesive property of PDA, the hydrophobic fabric showed robustness and mechanical durability. The modified fabric exhibited very good anti-contamination and self-cleaning property for both liquid and solid contamination.2. In-situ deposition method was used to coat textiles with PDA nanocapsules encapsulated hydrophobic agents that hence endowed textiles with superhydrophobicity and self-healing ability. These treated textiles exhibited self-healing capability after losing superhydrophobicity under multiple mechanical force such as stretch, compression and friction. In addition, the coated fabric displayed an excellent self-healable superhydrophobicity using mechanical washing. These superhydrophobic materials are suitable for technological application because of rapid self-healable performance under easier and natural stimuli.3. Facile approach of in-situ deposition was used to efficiently achieve self-healing superhydrophobicity on textiles by depositing of PDA capsules encapsulated ODA and Fe₃O₄ nanoparticles. The self-healing of superhydrophobicity was accelerated by the photothermogenesis effect of Fe₃O₄ nanoparticles under NIR light within 40 seconds. The coated fabric was also robust and durable against washing and mechanical abrasion without apparently changing its superhydrophobicity. In addition, NIR light can be used to realize controllable wettability gradient and pattern on this kind of textiles.4. Superamphiphobic textile with excellent mechanical durability, acid stability and selfhealable superamphiphobicity was prepared by one-step modification of PDA@FAS-PFOL capsules using in-situ deposition method. Meanwhile, re-entrant micro-nano structures can be established and low surface energy materials can be modified simultaneously on the textile without addition of other nanoparticles. The coated fabric showed high acid stability, and it was also robust and durable against mechanical damages. In addition, the modified textile displayed excellent self-healing performance against plasma and chemical damages. Importantly, the fabric coated with PDA@FAS-PFOL capsules has capability of anti-leakage and has potential application in impermeable engineering.