Simple modification of the primary product of TiO2 coated with SiO2 shell for the preparation of UV-aging-resistant, wear-resistant, superhydrophobic self-cleaning coatings

To improve the long-term UV stability of outdoor architectural coatings, a SiO₂ shell was coated onto the primary product of TiO 2 (P-TiO₂). The primary product of TiO 2 coated with SiO 2 shell (P-TiO 2 @SiO 2 ) composite particles were prepared via a sol–gel method, forming a uniform and dense SiO 2 coating layer on the P-TiO 2 surface to enhance its UV-shielding performance. The P-TiO₂@SiO₂ composite particles were used to construct a superhydrophobic coating by a simple two-step spraying process. KH560-modified E-51 epoxy resin was used as the adhesive layer, followed by spraying of the P-TiO₂@SiO₂/HDTMS hydrophobic layer. After 30 days of UV irradiation, the coatings containing P-TiO 2 @SiO 2 as the filler exhibited a color difference (ΔE*) of only 0.38 and a yellowing index (Δb*) of 0.23, significantly lower than those with pure P-TiO 2 (ΔE*=1.64, Δb*=0.76). It indicated that the SiO 2 shell effectively reduced color change and yellowing. Furthermore, the amorphous nanoscale SiO 2 uniformly coated on the P-TiO 2 surface contributed to the formation of a rough surface morphology. After modification, the superhydrophobic coatings achieved a water contact angle (WCA) of 161.5° and a sliding angle (WSA) of 1.23°. The coatings demonstrated excellent superhydrophobicity and self-cleaning performance on multiple substrates, including concrete, wood, and bricks. Moreover, they maintained stable superhydrophobicity after 60 days of continuous UV irradiation. Abrasion tests indicated that the incorporation of the KH560-modified epoxy resin primer significantly improved the wear resistance of the coatings. After 21 abrasion cycles, the coatings retained superhydrophobicity, whereas coatings without a primer lost superhydrophobicity after only 9 cycles. The superhydrophobic coatings prepared in this study were superhydrophobic, self-cleaning, UV-aging-resistant, fluorine-free, and wear-resistant without introducing traditional organic UV absorbers and hindered amine light stabilizers. The preparation process was simple, and the coatings exhibited stable and reliable performance, demonstrating promising applications in long-term outdoor protective and self-cleaning coatings. Download: Download high-res image (261KB) Download: Download full-size image