Chiang Mai Journal of Science

Superhydrophilic silica (SiO₂) nanoparticles (NPs) were successfully modified superhydrophobic SiO₂ NPs via a facile one-step reaction technique. The modified SiO₂ NPs with different alkyltrichlorosilanes (ATCS) were then coated on a glass substrate by dip-coating process. The effect of different ATCS chain lengths such as methyltrichlorosilane (C1), butyltrichlorosilane (C4), and octadecyltrichlorosilane (C18) on superhydrophobicity was investigated. The result showed the particle sizes of modified SiO₂ NPs slightly increases with the chain length. Likewise, the water contact angle (WCA) of C1, C4 and C18 modified SiO₂ NPs were 156º, 159º and 160º. Furthermore, the sliding angle (SA) of all the modified SiO₂ NPs are less than 3º. It is clearly indicated that ATCS with different chain lengths modified SiO₂ NPs were superhydrophobic. Interestingly, ATCSs modified SiO₂ NPs have high transparency with optical transmittance greater than 80%. This is a key opportunity for self-cleaning applications.