Integrating environmental robustness, energy-efficient recoatability and multi-scenario applicability into a single durable coating that can resist the accumulation of liquid, solid, and mold contaminants is critical for the sustainable development of the coatings industry, yet remains a significant challenge. Here, this issue is addressed by developing a novel hydrophilic-hydrophobic conversion strategy to engineer an environmentally robust organic/inorganic hybrid superhydrophobic coating with remarkable anti-soiling properties and pH-induced recoatability. This conversion, achieved through surface chemistry regulation incorporating hydrophobic hydrocarbon chains and aminopropyl functional groups, yields a coating with a high water contact angle (WCA) of 155.4 degrees and a low sliding angle (SA) of 1.3 degrees. Notably, the WCA can reversibly transition to 0 degrees within 15 s under pH adjustment. The wide range of the surface energy variations enables effective recoatability and restores surface wettability in damaged coatings, with an adhesion strength up to 5.34 MPa, allowing for the in-situ reuse of old coatings. The uniform distribution of modified silica nanoparticles within semi-cured epoxy matrix imparts satisfactory environmental durability, allowing the composite coating to retain its superhydrophobicity after enduring various harsh conditions, including 100 cycles of sandpaper abrasion, 70 cycles of tape-peeling, 120 h of water immersion, and 168 h of heat and humidity exposure. Additionally, the coating demonstrates enhanced anti-mold performance, achieving a grade 1 rating. This work introduces a novel design and fabrication method for multifunctional pH-triggered recoatable superhydrophobic coatings with enhanced environmental robustness that significantly extends their lifespan and adaptability.
As an important part of human cultural heritage, earthen sites are subject to damage caused by a variety of environmental factors, such as cracking, weathering, and flooding. Due to the low mechanical strength of earthen site materials, especially in humid environments, they are susceptible to hazards like moisture penetration, freeze-thaw cycles, and biological invasion. Superhydrophobic coatings show promising potential in the protection of earthen sites, with key properties that include waterproof performance, breathability, robustness, and transparency. By exploring various material systems and preparation methods, the current state of research on the protection of building materials with superhydrophobic materials has been demonstrated, highlighting advantages in the corrosion resistance, self-cleaning, frost prevention, anti-scaling, and other aspects. At the same time, it also points out the challenges faced in the practical application of earthen site protection and the prospects for future research. These include enhancing the bonding strength between the coating and soil particles, improving durability and breathability, and developing large-scale, low-cost, and efficient coating construction techniques.
In outdoor environment, the exterior walls surface of buildings always suffers from damages caused by ultraviolet radiations, temperature variation, abrasion and erosion phenomenon, dust pollution, and microbial adhesion: Thereby reducing their durability over time. In order to overcome these obstacles, the superhydrophobic coatings can be an advantageous solution to ensure long-term stable use by improving the exterior concrete walls durability. In this line, a fluorine-free water-repellent coating was developed through sol-gel method and successfully applied to concrete substrates by dip-coating technique. The coating was formulated with low surface energy polydimethylsiloxane (PDMS) and polymeric silica (PS) to simultaneously modify the microstructure and chemical properties of concrete substrate surface. The coated concrete substrate showed super-hydrophobicity with high water contact angle (WCA) over than 150 degrees. Besides, the self-cleaning property, mechanical robustness, stability under UV irradiations, resistance to temperature and humidity were investigated. The results indicated that the coated concrete substrate cannot be soiled by dust and can resist over than 300 cycles of abrasion test. It also presents resistance to temperature of 45 degrees C associated with a humidity of 80% during 720 hours and showed excellent resistance to prolonged exposure to UV irradiations during 1440 hours. Natural out-door aging tests have shown that the superhydrophobic coating is weather resistant.
Crude oil pollution in water and soil has resulted in considerable environmental damage. The utilization of hydrophobic and oleophilic sponge materials for the treatment of crude oil pollution has garnered significant interest, owing to their excellent selective adsorption performance. In this paper, superhydrophobic and superoleophilic sponges (SMF) are prepared by a simple silane hydrolysis-thermal curing method, which is low-cost, environmentally friendly, large-scale preparation, acid and alkali-resistant, and mechanically stable. They can be used for the remediation of oil pollutants in water and soil simultaneously, and show high efficiency, excellent stability, and biosafety. Under appropriate circumstances, SMF is capable of adsorbing up to 82.7 g/g of crude oil in water and eliminating over 70.0 % of crude oil in soil, while exhibiting exceptional recycling performance. Notably, this study introduces a novel technique that alters soil viscosity by controlling soil water content, in conjunction with SMF, for the removal of crude oil in soil. Consequently, SMF shows great promise for practical application in the remediation of oil pollutants in both water and soil.