A green approach for tunable fluorescent and superhydrophobic monodisperse polysilsesquioxane spheres

Hypothesis: Typically, calcination at high temperature could bring fluorescence to hybrid silica spheres prepared with 3-aminopropyltriethoxysilane and tetraethylorthosilicate, but they tended to be hydrophilic. Further extra modification is required to gain superhydrophobicity, which might probably block the fluorescence. Short side organic chains are very thermostable at high temperature. Therefore, it might be possible to produce superhydrophobic and fluorescent hybrid silica spheres through the co-condensation of organosilanes with short side organic chains and calcination at high temperature. Experiments: Methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) were co-condensed to prepare polysilsesquioxane (PSQ) spheres, which were subsequently calcinated at high temperature. The impact of MTMS/VTMS ratio on the chemical structures, fluorescence and wettability was investigated, and the applications of PSQ spheres were expanded. Findings: The PSQ spheres with the ratio of MTMS/VTMS as 3/1 and 2/2 exhibited strong fluorescence, and the calcination did not destroy the superhydrophobicity for the remaining of abundant methyl, vinyl, or ethyl groups. Our study provides an extremely green, simple and effective approach to prepare thermostable, fluorescent and superhydrophobic monodisperse silica spheres without using rare earth element, gold, conjugated polymer, phorsphore, fluoride chemical or organic solvent.