In this study, polyimide-silica (PI-silica) based hybrid coating compositions were prepared from tetraethoxysilane (TEOS), g-glycidyloxypropyl trimethoxy silane (GOTMS), and polyamic acid (PAA) via a combination of sol-gel and thermal imidization techniques. PAA was synthesized from 3,3(,4,4(-benzophenone tetracarboxylic dianhydride (BTDA) and 3,3'-Diaminodiphenyl sulfone (DDS) in N-Methyl-2-pyrrolidone (NMP). The silica content in the hybrid coatings was varied from 0 to 20 wt%. The structural characterization of the hybrid coatings was performed using FTIR and 29 Si-NMR spectroscopies. Results from both pendulum hardness and micro indentation test show that the hardness of hybrid coatings improves with the increase in silica content. The tensile tests also demonstrated that the mechanical properties at low silica content are rather striking. Their surface morphologies were characterized by scanning electron microscopy (SEM). SEM studies revealed that inorganic particles were distributed homogenously through the PI matrix. It was also found that, incorporation of the silica domains increased the thermal stability of the hybrid coatings.

In this article, a series of novel polyimide/ silica (PI/SiO 2 ) nanocomposite coating materials were prepared from tetraethoxysilane (TEOS), c-glycidyloxypropyltrimethoxysilane (GOTMS), and polyamic acid (PAA) via sol-gel technique. PAA was prepared by the reaction of 3,3 0 ,4,4 0 -benzophenone tetracarboxylic dianhydride (BTDA) and bis (3-aminophenyl) phenyphosphine oxide (BAPPO) in N-methyl-2-pyrrolidone (NMP). BAPPO was synthesized hydrogenation of bis (3-nitrophenyl) phenyphosphine oxide (BNPPO) in the presence of Pd/C. The silica content in the hybrid coating materials was varied from 0 to 20 wt %. The molecular structures of the composite materials were analyzed by means of Si-NMR spectroscopy techniques. The physical and mechanical properties of the nanocomposites were evaluated by various techniques such as, hardness, contact angle, and optical transmission and tensile tests. These measurements revealed that all the properties of the nanocomposite coatings were improved noticeable, by the addition of sol-gel precursor into the coating formulation. Thermogravimetric analysis showed that the incorporation of sol-gel precursor into the polyimide matrix leads to an enhancement in the thermal stability and also flame resistance properties of the coating material. The surface morphology of the hybrid coating was characterized by scanning electron microscopy (SEM). SEM studies indicated that nanometerscaled inorganic particles were homogenously dispersed throughout the polyimide matrix V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: [3256][3257][3258][3259][3260][3261][3262][3263][3264] 2010

In the present study, maleimide-modified epoxide resin containing UV-curable hybrid coating materials were prepared and coated on polycarbonate substrates in order to improve their surface properties. UV-curable, bismaleimide-modified aliphatic epoxy resin was prepared from N-(p-carboxyphenyl) maleimide (p-CPMI) and cycloaliphatic epoxy (Cyracure-6107) resin. The structure of the bismaleimide modified aliphatic epoxy resin was analyzed by FTIR and the characteristic absorption band for maleimide ring was clearly observed at 3100 cm S1 . Silica sol was prepared from tetraethylorthosilicate (TEOS) and methacryloxy propyl trimethoxysilane (MAPTMS) by sol-gel method. The coating formulations with different compositions were prepared from UV-curable bismaleimide-based epoxy oligomer and sol-gel mixture. The molecular structure of the hybrid coating material was analyzed by 29 Si-CP/ MAS NMR spectroscopy techniques. In the 29 Si CP/MAS NMR spectrum of the hybrid coating, mainly two kinds of signals were observed at S68 and S110 ppm that correspond to T 3 and Q 4 peaks, respectively. This result shows that a fully condensed structure was obtained. The thermal and morphological properties of these coatings materials were investigated by using TGA and SEM techniques. Hardness and abrasion resistance properties of coating materials were examined and both were found to increase with sol-gel precursor content of the coating. The photopolymerization kinetics was investigated by using RT-IR. 70% conversion was attained with the addition of 15 wt% of BMI resin into the acrylate-based coating formulation. It was found that the UV-curable organic-inorganic hybrid coatings improved the surface properties of polycarbonate.

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