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A series of abrasion-resistant coatings based on methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methacyloxypropyltrimethoxysilane (MEMO) were synthesized via a sol-gel method and applied to polycarbonate (PC) substrate. Through a comparison with an uncoated PC substrate, hardness, adhesion, and abrasion resistance of coated PC substrates were investigated. Fourier transform infrared (FTIR) spectra of these coatings before and after being cured indicated that the crosslinked structure of Si-O-Si was formed via the hydrolysis-condensation reactions of alkoxy silane. The optical test results showed that coated PC substrates possessed higher transmittance and lower haze than uncoated PC substrates. The hardness and adhesion data demonstrated that PC substrates coated with the hybrid coatings (MTMS/TEOS/MEMO coatings) possessed the greatest hardness and optimal adhesion. After 500 wear cycles, the PC substrate with MTMS/TEOS/MEMO coatings showed some grooves and wear tracks without any spallation or delamination, and there was a decrease of only 1.0-1.3% in transmittance and an increase of only 5.68-7.44% in haze. Whereas uncoated PC substrate and substrates with MTMS and MTMS/TEOS (molar ratio is 1.5:1) coatings exhibited a decrease of 3.3, 3.9, and 2.4% in transmittance and an increase of 30.19, 17.42, and 12.35% in haze, respectively. [ABSTRACT FROM AUTHOR]

UV curable, hard, transparent inorganic/organic composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. These hybrid coating materials were synthesized using a commercially available, acrylate end-capped polyester or polyurethane oligomeric resin (EBC80, EBC284), hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (TMSPM) as a coupling agent between the organic and inorganic phase, and a metal alkoxide, tetraethylorthosilicate (TEOS). The materials were applied on primer or oxygen plasma pretreated polycarbonate sheets and UV cured, followed by a thermal treatment to give a transparent coating with a good adhesion and abrasion resistance. The high transmission and the thermogravimetric behavior indicate the presence of a nanoscale hybrid composite, as is confirmed by SAXS and TEM measurements. In a Taber Abrasion Test, uncoated polycarbonate sheets exhibit a 48% decrease in light transmittance at 600 nm after 300 wear cycles, whereas the EBC80 hybrid coating system containing 9 wt% SiO2 (EBC80/25Si) shows only 28% decrease in light transmittance. A maximal improvement of the abrasion resistance is achieved when 23 wt% SiO2 is incorporated (EBC80/60Si, EBC284/60Si) with only 20% decrease in light transmittance. The abrasion resistance of glass is not yet encountered. For optimal results, it is essential that the rate of condensation of the silanol groups is sufficiently high to form a dense three-dimensional network. [ABSTRACT FROM AUTHOR]