关键词: 减反增透, 抗菌, 季铵盐, 二氧化硅空心球, 薄膜

Dual-functional thin films simultaneously demonstrating antireflective and antibacterial properties have important practical values in the fields of medicine and health. Unfortunately, related studies have so far been very limited. This work chose a quaternary ammonium salt with the longest carbon chain of C₁₈ as antibacterial agent, and used it to modify an acid-catalyzed silica sol via chemical bonding. The obtained quaternary ammonium salt modified acid-catalyzed silica sol (Q-ASNs) was subsequently mixed with a hollow silica nanospheres sol (HSNs) followed by stirring for 6 h to obtain a mixed sol. The volume percentage of Q-ASNs was varied as 3.1%, 4.9%, 6.7%, and 8.4%, respectively. In detail, Q-ASNs were synthesized as follows:1 mL tetraethyl orthosilicate (TEOS), 0.6 mL quaternary ammonium salt methanol solution (65 wt%), 13.6 mL ethanol, 0.45 mL water and 21 μL HCl were mixed followed by stirring at room temperature for 4 h and aging for at least one day. HSNs were prepared according to the following procedure:0.1 g poly(acrylic acid) (PAA) was dissolved in 4.5 mL ammonium hydroxide, and then it was mixed with 90 mL absolute ethanol under stirring. This was followed by the injection of 800 μL TEOS under vigorous magnetic stirring at room temperature in 40 min. After 10 h, a HSNs sol containing~30 nm hollow silica nanospheres formed. Before mixing Q-ASNs and HSNs, the HSNs were stirred in a ventilating cabinet for more than 24 h to remove ammonia. Antireflective/antibacterial dual-functional thin films were fabricated by dip-coating from the mixed sol of Q-ASNs and HSNs. The optical properties of the films were optimized by regulating the mixing ratio of the above-mentioned two sols. The optimal thin film coated glass substrate presented high transmittance (T_max=99.2%, T_ave=98.6%) in the visible wavelength range of 400~800 nm. The HSNs and the mixed sol were observed by transmission electron microscopy. The fabricated thin films were characterized by scanning electron microscopy, atomic force microscopy, transmission/reflection spectroscopy, X-ray photoelectron spectroscopy, and confocal laser scanning microscopy using a live/dead reagent. The current method is simple and easy for large-area coating without any high-temperature heat treatment, and is thus promising for practical applications.

Key words: antireflective, antibacterial, quaternary ammonium salt, hollow silica nanospheres, thin film