The present work addresses a market demand for high refractive index (n D) coatings. We prepared organic UV-curable oligomers with n D > 1.6. We found a novel way to prepare sulfur-containing UV-curable high n D oligomers of melamine and urethane acrylates. Refractive indices of the synthesized oligomers were between 1.552 and 1.615. Cure of the oligomers led to films with n D = 1.559 and 1.660. A wide variety of mechanical properties for UV-cured oligomers can be obtained with the facile synthesis methods used.

Summary: A new siloxane colloid was developed, for the use in UV‐curable inorganic‐organic hybrid films. The UV‐crosslinkable silica‐colloids were prepared from vinyltrimethoxysilane (VTMS) via a sol‐gel method. The structure of silica‐colloids was characterized using 1H NMR, 29Si NMR, FT‐IR, and matrix‐assisted laser desorption/ionization (MALDI‐TOF) mass spectrometry (MS). The particle size of the siloxane colloid was evaluated using atomic force microscopy (AFM) and small angle light scattering (SALS). Organic phase was based on an acrylated polyester which was synthesized using 1,4‐cyclohexane dimethanol (1,4‐CHDM), neopentyl glycol (NPG), 1,6‐hexanediol (1,6‐HD), maleic anhydride (MA), adipic acid (ADA), and acrylic acid (AA). The acrylated polyester was characterized by gel‐permeation chromatography (GPC) and acid titration. A photo‐initiator was added to the formulation and the UV‐crosslinking reaction of hybrid film was monitored via photo‐differential scanning calorimetry (Photo‐DSC) and real‐time infrared spectroscopy (RT‐IR). The effect of the concentration of VTMS colloids, UV‐light intensity, and exposure time on the polymerization rate was investigated and compared with an inorganic‐organic hybrid film based on TEOS oligomers. Photo‐DSC and RT‐IR results indicated that VTMS colloids can greatly increase free radical polymerization rate and the VTMS colloids functioned effectively as cross‐linker and reactive diluent. AFM and small angle light scattering (SALS) data showed that the silica‐colloids were well dispersed in the organic phase. magnified image

The free-radical reaction kinetics and microgel formation of UV-curing unsaturated polyester acrylates were studied in terms of the effects of internal maleic and terminal acrylate unsaturations. A triacrylate-functional monomer, trimethylolpropane triacrylate, was used as the reactive diluent. A time-resolved Fourier transform infrared technique was used to evaluate the consumption of double bonds and showed that internal (maleic) double bonds were involved in microgel formation at a rate similar to that of the more reactive terminal (acrylic) double bonds. Dynamic light scattering was used to measure the microgel particle size. The introduction of internal unsaturations caused smaller microgels, whereas terminal acrylate unsaturations resulted in larger particle sizes. These results were attributed to the higher tendency of the internal maleic double bonds toward intramolecular cyclization reactions. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6544-6557, 2006

An unsaturated polyester, based on maleic anhydride, 1,6-hexanediol, and trimethylol propane, was formulated with tetraethylorthosilicate (TEOS) oligomers and a coupling agent to prepare inorganic/organic hybrid films. TEOS oligomers were prepared through the hydrolysis and condensation of TEOS with water, and 3-(triethoxysilyl)propylisocyanate was used as the coupling agent between the organic and inorganic phases. The hybrid materials were cured by moisture via sol-gel chemistry and by the UV curing of unsaturated polyesters. To compare the properties of the moisture-cured inorganic/organic hybrid films, a conventional 2K polyurethane system was also prepared. The tensile, adhesion, abrasion, and fracture toughness properties were investigated as functions of the coupling agent and relative amount of UV cure versus thermal cure. Although no difference could be observed in the tensile properties, the abrasion resistance, fracture toughness, and adhesion were enhanced by the incorporation of TEOS oligomers into polyurethane films. Also, the abrasion resistance, fracture toughness, and tensile properties were increased with both moisture and UV exposure.

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