Preparation And Properties Of Transparent ZNO/Silicone Nanocomposites

Because transparent organic/inorganic nanocomposites not only have the advantagesof both polymer (such as light weight, easy processing and flexibility) and inorganicnanomaterial (such as high refractive index, high hardness, good heat resistance andUV-shielding properties), but also have ability to produce more superior performance bysynergic interactions within each components, these nanocomposites are widely used in thefield of fiber optic, LED packaging materials, optical lenses, flat panel displays and otheroptoelectronic applications, besides, they also possess attractive development prospects.However, inorganic nanoparticles are prone to aggregate and disperse nonuniformly inorganic polymer, so this phenomenon not only reduces the visible light transmittances ofmaterials but also affects other properties such as thermal properties and dielectricproperties. Consequently, it is an important subject in this field that how to improve thedispersity of inorganic nanoparticles in organic polymers and enhance interfacial bondingbetween two phases.The performance of nanocomposites depend on their basic components, ZnOnanoparticles were selected as inorganic filler because they have some advantages such ashigh UV absorption, high refractive index, high strength, good chemical stability,non-toxic and environment-friendly, silicone was chosen as polymer matrix due to itsexcellent performance such as outstanding visible light transmittance, high thermalstability and resistance to ultraviolet radiation, in addition, two aspects of research work inthis thesis are as follows:First, poly (methyl methacrylate)(PMMA) were grafted from ZnO nanoparticles byatom transfer radical polymerization (ATRP) technique and prepared ZnO-PMMA nanoparticles, the UV-curable ZnO-PMMA/acrylic silicone resin (ZnO-PMMA/SA)nanocomposites were prepared on the basis of the above, ZnO/SA nanocomposites werealso prepared in order to compare with ZnO-PMMA/SA nanocomposites, the effects ofPMMA on the dispersion of ZnO nanoparticles in polymer matrix and the dielectricproperties, thermal properties, optical properties of nanocomposite were discussedsystematically. Results show that PMMA make ZnO-PMMA/SA composites possesshigher UV-shielding efficiency, transmittance of the visible light, better thermal stabilityand lower dielectric loss compared with ZnO/SA composites. Therefore，the resultssuggest that the method of ATRP technique is a new approach to develop highperformance transparent optoelectronic materials for cutting-edge industries.Second, ZnO quantum dots (QDs) were modified by combination of MgO inorganicpassivation layer and vinyl triethoxysilane (A151), thus ZMO-A QDs were prepared, thenthe ZMO-A/S nanocomposites were prepared on the basis of the above, furthermore, theZnO-A/S nanocomposites containing organic modified ZnO-A nanoparticles and ZnO-A/Snanocomposites containing unmodified ZnO QDs were also prepared for comparison. Theeffects of MgO inorganic passivation layer and A151on the dispersion of ZnO QDs insilicone rubber and the optical properties and thermal properties of nanocomposite werediscussed systematically. Among them, the combined modification was found to be morebeneficial to improve dispersion of QDs in silicone rubber compared with othermodification methods which confirmed by transmission electron microscopy and dynamicmechanical thermal analysis, at the same time, the combined modification significantlyimprove the thermal stability, fluorescent properties and transmittance of the visible lightof ZnO/S and ZnO-A/S nanocomposites.