Durable ER@SiO2@PDMS superhydrophobic composite designed by double crosslinking strategy for efficient oil-water separation

Wettability behavior of DTMS modified SiO2: Experimental and molecular dynamics study

In this research, the wetting behavior of SiO2 modified with dodecyltrimethoxysilane (DTMS) was explored using both experimental and molecular dynamics (MD) simulation approaches. The experimental results reveal that DTMS can chemically bond to the SiO2 surface, and the contact angle (CA) reaches the maximum value of 157.7° when the mass of DTMS is twice that of SiO2. The different wetting behaviors caused by DTMS grafting were analyzed by CA fitting, ionic pairs, concentration distribution, molecule orientation, and interfacial interaction energy. The results demonstrate that a 25 % DTMS grafting rate resulted in a maximum CA of 158.2°, which is ascribed to the disruption of interfacial hydrogen bonding and changes in the hydration structure caused by DTMS grafting. Moreover, the above hydrophobic SiO2 model shows a slight decrease in CA as the water temperature increases, which is consistent with the experimental findings. In contrast, an opposite change was observed for the pristine SiO2 model. Although the higher water temperature enhances the diffusion capacity of water molecules in both models, the difference in interfacial interactions is responsible for the change in CA. We hope this finding will contribute to a deeper understanding of the wetting adjustment of SiO2.

Durability and Additional Properties of Anodized Aluminum-Based Coatings with Different Wettability under Natural Conditions

The study aimed to test the durability of coatings under natural conditions. The present study focused on the changes in wettability and additional properties of the coatings under natural conditions. The specimens were subjected to outdoor exposure and additionally immersed in the pond. Impregnating porous anodized aluminum is a popular production method for hydrophobic and superhydrophobic surfaces. However, prolonged exposure of such coatings to natural conditions causes leaching of the impregnate and, thus, the loss of hydrophobic properties. After the loss of hydrophobic properties, all kinds of impurities and fouling adhere better to the porous structure. Additionally, deterioration of anti-icing and anti-corrosion properties was observed. Finally, the self-cleaning, anti-fouling, anti-icing and anti-corrosion properties were comparable or even worse to those of the hydrophilic coating. In the case of superhydrophobic specimens, during outdoor exposure there was no loss of superhydrophobicity, self-cleaning and anti-corrosion properties. Still, despite this, the icing delay time dropped. During outdoor exposure, the structure, which initially had anti-icing properties, may degrade. Nevertheless, the hierarchical structure responsible for the superhydrophobic effect can still be preserved. The superhydrophobic coating initially had the best anti-fouling properties. However, the coating was also gradually losing its superhydrophobic properties during water immersion.

Transparent Oil-Water Separating Spiky SiO2 Nanoparticle Supramolecular Polymer Superhydrophobic Coatings

A potential application of spiky SiO₂ nanoparticles (NPs) with tubular and rough surfaces is investigated as superhydrophobic coatings, for their unique transparent, fluorinate-free, and environmentally friendly properties. This study demonstrates a facile method for the successful fabrication of superhydrophobic coatings and SiO₂ @polydimethylsiloxane (PDMS) using spiky SiO₂ NPs, N-coordinated boroxines, and PDMS. Combined with spray coating technology, this method of superhydrophobic coating can be simply applied to both hydrophilic and hydrophobic surfaces, including wood, fabric, glass, metal, sponge, and paper. The nanocomposite coating on the glass surface showed both excellent superhydrophobicity and high transparency, with a contact angle of 165.4 ± 1.0° and 96.93% transmittance at 550 nm, respectively. SiO₂ @PDMS-modified glass substrate is found to be resilient to UV irradiation, water, and high temperature treatments at ambient conditions. Experimental data demonstrated that the simple but effective combination of N-boroxine-PDMS and spiky SiO₂ NPs produces a layered coating material that exhibits many good integrated surface properties, including stability, transparency, superhydrophobicity, and oil-water separation.