Hydrophilic nature of silicate glass surfaces as a function of exposure condition

The work presented compares the hydrophilic nature of fused silica, BK-7 and soda lime silicate (SLS) glass surfaces as a function of exposure conditions. Oxygen (O2) plasma, water (H2O) plasma and a combination treatment of ultraviolet (UV) radiation (340 nm, 0.4 W/m2) in an aqueous environment (UV/H2O) were used as the exposure treatments. The hydrophilic character of the surfaces was based on Fourier transform infrared reflectance studies (4000–3000 cm−1 region) and contact angle analysis. It was found that the SLS glass was equally affected by all three exposure conditions, at least to the penetration depth of the IR reflection analysis (84° to the normal). A more hydrophilic behavior was achieved for fused silica and BK-7 using either the UV/H2O treatment or the H2O plasma treatment. It was confirmed by IR analysis that the O2 plasma treatment of fused silica and BK-7 glass resulted in free silanol groups at the surface, which contributed to the lower hydrophilicity after treatment.