Multifunctional Flexible Hard Coatings with Weathering Resistance and Heat-Shielding Properties

Hard, flexible, transparent, and hydrophobic multifunctional coatings have a wide range of applications, but they do not adequately protect against harsh conditions, especially photoaging. In this study, SiO2 and Al2O3 nanoparticles were first modified by silazane and epoxy-functionalized silanes and then reacted with a polyetheramine curing agent to prepare highly crosslinked multifunctional hybrid coatings at room temperature. Due to the integration of siloxane nanoparticles and a polymer network, the multifunctional coatings presented outstanding hardness (4H), flexibility (bending diameter of 10 mm), and transmittance (>97%). The introduction of low-surface-energy PDMS and methyl-rich HMDS endowed the coatings with good hydrophobicity (water contact angle = 141.37°). The high reflectivity of SiO2 and Al2O3 in the solar spectral region can help prevent photoaging of the coatings, improve their heat-shielding effect, and broaden their application scenarios. Compared with the traditional manufacturing methods, this study did not need ultraviolet irradiation, and the multifunctional transparent coatings could be prepared through a simple and efficient step-by-step strategy.