Controlled synthesis of non-functionalized POSS nanoparticles with hydrophobic to hydrophilic wettability transition

The surface characteristics of nanoparticles is essential for practical applications, which is usually modulated by chemical modification, high-temperature treatment, and laser etching. Wherein, realizing the wettability transition from hydrophobic to hydrophilic nanoparticle surfaces without physical or chemical modifications remains a great challenge. Here, we propose a strategy to modulate the surface wettability of POSS nanoparticles by controlling the amount of deionized water. In the absence of any modifier, the prepared POSS nanoparticles can be transformed from hydrophobic to hydrophilic by only gradually increasing the deionized water content in the reaction. It is demonstrated in the FTIR and XPS test results that the density of Si-OH on the surface of the nanoparticles increases when the content of deionized water is gradually increased in the reaction process. And the generation of Si-OH is related to the hydrolysis and condensation rate of POSS molecules. The SEM images and particle size statistics displayed a clear dependence between the size of synthesized POSS particles and the varying deionized water content. It can be inferred that the variation in deionized water content during the reaction impacts the surface wettability of the synthesized POSS nanoparticles. This effect is primarily related to the hydrolysis and condensation rates of the POSS molecules, monomer concentration and the particle size of the resulting particles. Increasing the deionized water content leads to an acceleration in the rates of hydrolysis and condensation. This results in a higher production of Si-OH groups through hydrolysis and an increase in the density of Si-OH on the surface of the POSS nanoparticles. Simultaneously, the particle size decreases. The combination of increased Si-OH density and smaller particle size enhances the hydrophilicity of the nanoparticles. In addition, fully wettable and controllable coatings were prepared based on hydrophilic and hydrophobic tunable POSS nanoparticles, and their ability to delay icing at low temperatures was explored, showing excellent anti-icing performance.