Saeed Bastani

Effects of silane precursors on curing behavior of UV-curable hybrid coatings

This study demonstrates the effect of some commonly used silane precursors on curing behavior and photopolymerization kinetics of UV-curable hybrid coatings. Tetraethoxyorthosilane (TEOS), vinyltrimethoxysilane (VTMS), and 3-methacryloxypropyltrimethoxysilane (MPS) were polymerized under acidic conditions by the sol–gel method. The resulting structure of the tested siloxane oligomers was characterized using 29Si-NMR and 1H-NMR spectroscopy. Photo-DSC was used to evaluate photocuring enthalpy. A fully integrated model was applied to investigate propagation rate coefficients and to identify the most effective termination mechanism (monomolecular, bimolecular, or mixed). Results showed that oligomers containing MPS effectively promoted total heat of the polymerization process and consequently affected the maximum rate of polymerization and final double bond conversion. Enthalpy rating for samples containing MPS was higher than that of those containing VTMS, showing that MPS was more compatible with the acrylate systems. In addition, evaluations for photopolymerization kinetic constants proved that non-functional oligomers containing TEOS caused radical trapping and increased activity of the monomolecular termination mechanism.Graphical Abstract

UV-Curable Nanocomposite Coatings and Materials

Abstract Photopolymerization is a rapidly expanding technology because it offers several advantages. For instance, it is solvent-free and energy-efficient and can be used for heat-sensitive substances. Composites are materials consisting of two organic and inorganic compounds collecting the process ability of organic materials as well as hardness and ductility of inorganic materials. This chapter covers the theoretical aspects of UV-curing process and some general challenges in preparation of nanocomposites, including dispersion of nanoparticles in matrix and colloidal stability as well as sol gel-based composites. In addition, some characterization techniques of cured materials, morphology of nanocomposites, monitoring of photo-cross-linking, and UV-curing kinetics are discussed. Physical and mechanical properties of UV-curable composite coatings and some of their application are introduced. Finally, new approaches, trends, and discoveries are presented.