Preparation Of Organic/Inorganic Nanocomposites By UV Photopolymerization

Preparation of organic/inorganic nanocomposites by UV photopolymerization combines the advantages of both nanocomposites and the UV photopolymerization. To prepare organic/inorganic nanocomposites with excellent properties, different types of organic/inorganic nanocomposites were prepared through different purposes based on the different UV photopolymerization components in the thesis, and the organic/inorganic components were bonded together through chemical bond. The main results was emphasized.1. Ammonium surfactants with methacryloxy group of different chain length were synthesized via Michael-Addition and quatemization reaction. The Na-montmorillonite(Na-MMT) was modified by the ammonium surfactants with polymerizable group through cationic exchange. MMT/polyurethane nanocomposites had been produced by UV initiated polymerization with 5w% organoclay loading. XRD, DMA and the study of tensile properties indicated that the mechanical and physical properties of the nanocomposites increased with the chain length of modifiers.2. Polymerizable ammonium surfactants with two methacrylate alkyl chains were successfully synthesized via Michael-Addition and quaternization reaction. Organoclays containing reactive methacrylate groups were prepared by cationic exchange process. Nanocomposites have been produced by UV initiated polymerization with different organoclay loadings. X-ray diffraction (XRD) spectroscopy showed that the d spacing of organoclay increased with increment of methacrylate alkyl chains length. After organoclay was dispersed in urethane acrylate resin and photopolymerized, the d spacing decreased with increment of the methacrylate alky chains length, which was different to that of the polymerizable ammonium surfactants with methacrylate alkyl single chain. Dynamic mechanical analysis (DMA) showed nanocomposites containing reactive organoclay had high glass transition temperature and storage modulus. Tensile analysis implied that incorporation of reactive organoclay could enhance mechanical and tensile properties of nanocomposites dramatically.3. A photoinitiator 1173TDI was synthesized, which was intercalated into montmorillonite through cationic exchange. The intercalated photoinitiator also had high photoinitiation efficiency, even only 1/100(w/w) modified-clay could initiate the radical polymerization with the 87% acrylate conversion on 20mW/cm~2 exposure. XRD and TEM showed that the MMT was partly intercalated and partly exfoliated in the polymer matrix.4. Reactive epoxy groups were intercalated into the layered silicates through sol-gel reaction of triethoxysilanepropylamineformylethyl trimethyl ammonium iodide (APS) and 3-glycidoxypropyl trimethoxysilane (GPS). The modified organoclay through sol-gel reaction were easy to be dispersed in acetone and formed stable slurry. The slurry was then mixed extensively with epoxy resin to form epoxy-nanoclay composites by photopolymerization. XRD and TEM study showed that the modified clay had good affinity to the epoxy resin, and the resulting epoxy-nanoclay composites exhibited a high degree of clay exfoliation from order exfoliation to highly disorder exfoliation and a good thermal stability property with the increment of GPS.5. Photoinitiator 1173IPS was intercalated into the montmorillonite (MMT) through sol-gel reaction of triethoxysilanepropylamineformylethyl trimethyl ammonium iodide (APS) and 1173IPS. XRD indicated that the d spacing of the modified clay was enlarged to 2.26-3.65nm. The modified clay was then mixed with urethaneacylate oligomer and MMT/polyurethane nanocomposites were prepared by photopolymerization. Real-time FTIR (RTIR) results showed the system had almost the same final conversion but different polymerization rates with different ratios of APS/1173IPS modified clay. XRD and TEM results showed that the modified-clay was exfoliated and dispersed in parallelly alignments as multilayers in the organic matrix.6. UV-curable nanocomposites were prepared by the in-situ photopolymerizaton with nanosilica obtained from sol-gel process of tetraethyl orthosilicate (TEOS), 3-(triethyloxysilyl) propyl methacrylate (MAPS) and 1173IPS. The photoinitiator 2-hydroxy-2-methyl-1-phenylpropane-1-one (1173) was anchored onto the surface of the nanosilica with or without methacryloxypropyltrimethoxysilane (MAPS) modification. The Real-Time Fourier transform IR (RTIR) showed that the double bond conversion and curing rate increased with the increment of 1173IPS, and nanocomposites containning the nanosilica particles without MAPS modification had much higher curing rates than those containning the nanosilica particles with MAPS modification. Transmission electron microscopy (TEM) indicated that MAPS and 1173IPS played an important role on the uniformal dispersion of the nanosilica in the organic matrix. With the increment of 1173IPS photoinitiator, the uniformity was improved, no phase separation took place and with the addition of MAPS, the uniformity was further improved. UV - vis transmittance showed that with the increment of 1173IPS photoinitiator, the transparence was also improved, with the addition of MAPS, the transparence was further improved.