Synthesis and Characterization of Novel Organic-Inorganic Nancomposite Coatings
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SYNTHESIS AND CHARACTERIZATION OF NOVEL ORGANIC-INORGANIC NANCOMPOSITE COATINGS BRIAN P. MOSHER, TAOFANG ZENG North Carolina State University, Dept of Mechanical and Aerospace Engineering, Raleigh, NC 27695
ABSTRACT In this paper, we report the synthesis and characterization of three novel water-based nanocomposite coatings. Throughout the paper, these coatings will be referred to as coatings 1, 2 and 3. The coatings are silica-based and are sol-gel derived using surfactant assemblies, with aluminum perchlorate as a catalyst. After synthesis, curing causes cross-link polymerization of silica, forming Si-O-Si network. The formation of this 3-Dimensional network can be verified using Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). Incorporating metal oxide nanoparticles gives the material unique properties.
INTRODUCTION
The sol-gel process was originally developed for the preparation of inorganic glasses.1,2 The mild reaction conditions of sol-gel process allow the incorporation of an inorganic component into organic materials. Thus it is very favorable for the synthesis of organic-inorganic nancomposite materials.3 Composite organic-inorganic multilayers comprising silicate have recently been prepared by continuous self-assembly from silica-surfactant-monomer species spontaneously organizing into lyotropic mesophases partitioning the organic and inorganic precursors within a laminated structure, mimicking that of nacre. 4,5 Organic modification of the silicates allows precise control of surface properties and pore sizes of mesoporous sieves for specific applications, while stabilizing the material towards hydrolysis.6 Further, under acid catalyst and carefully controlled reaction conditions, transparent and monolithic hybrid/composite materials can be obtained through the sol-gel process.7 In recent years, federal regulations have become stricter on Hazardous Air Pollutants (HAPs) and Volatile Organic Compounds (VOCs), creating higher demand for cleaner and safer synthesis of coatings. Waterbased coatings create very low VOCs and virtually no HAPs, making them ideal materials in industry. Further, when applying water based coatings, machinery can be cleaned much more easily, without the use of solvents or other chemicals. However, because water-based coatings are relatively new, their mechanical properties are not as well developed as those of organic solvent-based coatings. Also, the addition of specific nanosized particles allows fine-tuning of the material’s properties, allowing the material to be tailored to different applications. In this study, we have synthesized monolithic and transparent composite materials via acid-catalyzed solgel reactions of inorganic precursor. We report the synthesis and characterization three novel water-based nanocomposite coatings, which are dense, abrasion resistant and UV absorbent.
MATERIALS AND METHODS Coating 1: Materials: Ludox TMA Colloidal Silica, Grace Davison, used as received 3-Glycidoxypropltrimethoxysilane (GLYMO),
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