Isomer effect on chemical reactivity and superhydrophobicity of chlorosilane modified SiO2 nanoparticles prepared by one-step reaction

Superhydrophobic (SH) silica (SiO2) nanoparticles (NPs) were successfully synthesized through a simple and facile technique. The effect of chlorosilane isomers was investigated by the grafting of butyltrichlorosilane (C4But) and dichloro (3-chloropropyl) methylsilane (C4Di) on superhydrophilic SiO2 NPs. The SEM results displayed that the particle size of C4Di modified SiO2 (C4Di-SiO2) NPs was larger than C4But modified SiO2 (C4But-SiO2). This can be due to the steric effect of the methyl group on the C4Di segment. The wetting analysis revealed that C4Di-SiO2 cannot reach SH criteria as it showed a water contact angle (WCA) of 149° and a sliding angle (SA) over 10°, while C4But-SiO2 showed a SH surface with a WCA of 159° and SA of 2°. Interestingly, the modified SiO2 NPs created a transparent film on the glass substrate which is a key opportunity for self-cleaning application.