ABSTRACT
Silica sol was prepared by acid catalyzed sol-gel process using tetraethylorthosilicate (TEOS) as precursor and dimethyldietoxysilane (DDS) as pore-forming agent. A novel kind of monolayer microporous silica anti-reflective (AR) coating was obtained on K9 glass substrate by dip-coating technique and then heat treated at 500 degrees C. The effects of different DDS/TEOS molar ratios on refractive index, transmittance and hardness were investigated. A positive correlation was found between the transmittance and the DDS/TEOS molar ratio due to the increasing porosity. The maximum transmittance can reach 99.7% with the molar ratio of DDS/TEOS rising to 1 : 1. Meanwhile, the refractive index was found quite close to the ideal value 1.22. Nevertheless, higher molar ratio will lead to a bad film-forming property. On the other hand, the hardness of the coatings decreased with the DDS increasing but still remained more than 2 h when the transmittance reached highest. Besides, these coatings exhibit a well abrasion-resistance and excellent adhesivity. The maximum transmittance was only dropped by 0.071% and 0.112% after abrasion for 500 and 1 000 times respectively. Accelerated corrosion tests indicated that the transmittance of traditional coatings rapidly fell down to the substrate level (-92%) after immersion for 5 min, while the transmittance of our novel coating almost linearly decreased and was kept 93.2% after 56 min. In other words, the environment-resistance of our novel silica AR coating is ten times higher than that of traditional ones. The promotions of the coating performances benefit from its micropore structure (-0. 4 nm) with which water molecule can be effectively prevented. With its high transmittance, good mechanical properties and high environment-resistance, this kind of novel coating has a potential application in the field of solar glass modification to improve its anti-reflective properties.
ABSTRACT
A group of low-T(g) photorefractive polymers of double function with carbazole and p-nitrodiazencarbazole called P-2, P-3 and P-4 were synthesized by means of different proportional diazonium salts being diazo-coupled with the poly [bis(6-carbazolhexyloxy)] phosphazene(P-1). P-2, P-3 and P-4 were characterized by 31P NMR, 1H NMR, IR, UV-Vis, GPC, TG and DSC. The result showed that P-2, P-3 and P-4 have good heat stability (T(d) approximately 300 degrees C) and a lower glass transition temperature (T(g) approximately 30-40 degrees C). Their fluorescence properties were studied by photoluminescence and the result showed that P-1 has a stronger fluorescence properties and fluorescence intensity. P-2, P-3 and P-4 have varying degrees of quenching after nitro joining. The fluorescence properties were related with numbers of carbazole and nitro and their molecular space structure.
