Reversible Thermochromic Superhydrophobic BiVO₄ Hybrid Pigments Coatings with Self-Cleaning Performance and Environmental Stability Based on Kaolinite

Abstract

The inferior acid resistance and high cost of BiVO4 pigments seriously hinder their wide applications in some fields. Inspired by the superhydrophobic properties of some plants and insects in nature, the reversible thermochromic superhydrophobic coatings with self-cleaning performance and environmental stability were successfully designed by combining with the surface roughness of kaolinite/BiVO4 hybrid pigments (Kaol/BiVO4–HP) and the modification with hexadecyltrimethoxysilane (HDTMS). When the concentration of HDTMS was 4.58 mmol/L, the yellow superhydrophobic coatings exhibited excellent self-cleaning properties and chemical and environmental stability. Furthermore, the superhydrophobic Kaol/BiVO4–HP coatings exhibited the reversible thermochromic behavior with the change of the external temperatures from room temperature to 270 °C. Interestingly, this facile strategy also can be used to fabricate a series of superhydrophobic clay mineral/BiVO4–HP coatings based on the different clay minerals, and there was no relationship between the superhydrophobic properties of the coatings and the morphologies of clay minerals, which was different from the reported color superhydrophobic coatings prepared with Maya-like blue pigments. Thus, the low-cost and thermochromic superhydrophobic clay mineral/BiVO4–HP coatings presented a promising application in temperature sensors and switches with the excellent weather resistance to record and monitor the temperature changes.

Mechanochemical synthesis of multifunctional kaolin@BiVO4 hybrid pigments for coloring and reinforcing of acrylonitrile‐butadiene‐styrene

“…Figure 1e exhibits the FTIR spectra of kaolin, kaolin@BiVO 4 ‐HP and KH‐570 modified kaolin@BiVO 4 ‐HP, which can reveal the changes of the surface functional groups and structural features of the samples. In the case of kaolin, the characteristic absorption bands of the stretching vibrations of hydroxyl groups (AlOH and SiOH), SiOSi, and the physically adsorbed water are found at 3500–3200, 1034, and 1630 cm −1 , respectively 20 . The typical absorption bands of BiVO 4 are observed at 467, 716, and 833 cm −1 , the bands of 716 and 833 cm −1 are ascribed to the symmetric and asymmetric stretching bending vibrations of VO of VO 4 3− , 19 and the band at 467 cm −1 is attributed to the BiO stretching and bending vibration 20,28 .…”

“…In the case of kaolin, the characteristic absorption bands of the stretching vibrations of hydroxyl groups (AlOH and SiOH), SiOSi, and the physically adsorbed water are found at 3500–3200, 1034, and 1630 cm −1 , respectively 20 . The typical absorption bands of BiVO 4 are observed at 467, 716, and 833 cm −1 , the bands of 716 and 833 cm −1 are ascribed to the symmetric and asymmetric stretching bending vibrations of VO of VO 4 3− , 19 and the band at 467 cm −1 is attributed to the BiO stretching and bending vibration 20,28 . After modification with KH‐570, the absorption bands located at 2927 and 2853 cm −1 correspond to the CH stretching vibration of CH 2 and CH 3 of KH‐570, respectively, and the absorption band at 1399 cm −1 are attributed to the CO stretching vibration of KH‐570, 28 which indicates that kaolin@BiVO 4 ‐HP is successfully modified with KH‐570.…”

“…20 The typical absorption bands of BiVO 4 are observed at 467, 716, and 833 cm À1 , the bands of 716 and 833 cm À1 are ascribed to the symmetric and asymmetric stretching bending vibrations of V O of VO 4 3À , 19 and the band at 467 cm À1 is attributed to the Bi O stretching and bending vibration. 20,28 After modification with KH-570, the absorption bands located at 2927 and 2853 cm À1 correspond to the C H stretching vibration of CH 2 and CH 3 of KH-570, respectively, and the absorption band at 1399 cm À1 are attributed to the C O stretching vibration of KH-570, 28 which indicates that kaolin@BiVO 4 -HP is successfully modified with KH-570. After introduction of BiVO 4 nanoparticles, it is obvious that the BiVO 4 nanoparticles with a diameter of 10-20 nm is uniformly anchored on the surface of flake matrix (Figure 1f), and the interplanar spacing of 0.184 nm corresponds to (121) crystal plane of BiVO 4 .…”

“…In recent years, clay minerals-based cobalt blue hybrid pigments, 17,18 bismuth yellow hybrid pigments, 19,20 and iron red hybrid pigments 21 were prepared by various liquid-phase technologies including chemical precipitation method, sol-gel method, hydrothermal, or microwave-assisted hydrothermal method. It was confirmed that incorporation of clay minerals obviously reduced the production cost and enhanced the color properties of inorganic pigments due to the doping of chemical compositions of clay minerals and the control of the particle size and dispersion.…”

Super pressure-resistant superhydrophobic fabrics with real self-cleaning performance

“…The color parameters of the pristine, contaminated and self-cleaned fabrics were evaluated using the CIE 1976 L∗a∗b∗ colorimetric method with a Color-Eye automatic differential colorimeter (X-Rite, Ci 7800), where L∗ is the color lightness (0 for black and 100 for white), a∗ is the red (+)/green (−) axis, and b∗ is the yellow (+)/blue (−) axis ( Wang et al., 2021 ). The changes in L∗ , a∗ and b∗ values were used to evaluate self-cleaning performance of the fabrics.…”