Design And Synthesis Of Polymerizable Nanoparticles And The Resulting High Refractive Index Hybrid Optical Materials

The optical materials with high refractive index have attracted considerableattention due to its potential application in optical electronic and information storagefields, such as the LED encapsulate materials, optical waveguides, anti-reflectioncoatings, optical storage media, and volume holographics and so on. Therefore,research of high refractive index optical nanocomposites is becoming aninterdisciplinary subject.The traditional optical organic materials have a small adjustable RI range (1.3-1.7)due to their chemical structure limitation, which restricts their practical application inthe field of optics. In the past decades, researchers incorporated inorganicnanoparticles with high refractive index into polymers to improve the refractive indexof the polymer and achieved many achievements. Generally, inorganic nanoparticlesare easily to aggregate owing to their high surface area, which will directly sacrificethe transparency of the final materials. In the past research, the inorganicnanoparticles always experienced a surface modification process, which improved thecompatibility between inorganic nanoparticles and polymer matrix. However, itdecreased the refractive index of the pristine nanoparticles at the same time. It is stillan important topic to incorporate appropriately sized nanoparticles into a polymermatrix without aggregation and thus to prepare transparent materials with a highrefractive index via a simple and effective method. In the second Chapter, polymerizable ZnS NPs are prepared in the monomers viaa novel strategy and a series of transparent bulk nanocomposite materials are obtainedby free radical initiated in situ bulk polymerization using these polymerizable ZnSNPs. From the TEM results, we know that the obtained polymerizable ZnS NPs with asmall size of4–5nm have a good dispersion in the monomers. The FTIR and NMRresult indicate that the PA molecules were attached to the surface of the ZnS and havean interaction with the zinc ions. The obtained bulk nanocomposites have a goodtransmittance in the visible range and its refractive index can be continuouslyregulated in the range of1.527to1.598by changing the content of polymerizable ZnSNPs. The novel strategy opens a new gate to fabricate these kinds of nanocompositesand thus extend the application of the nanocomposites in optical devices.In the third Chapter, stable GNPs with a diameter of3–5nm have beensynthesized in DMAA by the solvothermal method. The refractive index of theGNPs–PDMAA nanocomposite films could be continuously regulated in the range of1.516to1.976by the content of GNPs. Additionally, the refractive index could reach1.976with50wt%GNP content. We also obtained nanocomposite films with a higherrefractive index above2.0by improving the refractive index of the polymer matrices.Based on the polymerizable GNPs, we also prepared a series of free-standing filmswith different weight contents of GNPs, and the refractive index of theseself-supporting films can be continuously regulated in the range of1.534to1.583.And we also find that the GNPs play a key role in the mechanical properties of thenanocomposites.In the forth Chapter, ultrahigh refractive index Si NPs-based transparentnanocomposite films are obtained by embedding quantum-sized and almost oxide-freeSi NPs into polymer matrices via an effective and convenient chemical method. Weuse vinyl-terminated monomers as the solvent, ligand, and monomer to produce thepolymerizable Si NPs. The polymerizable Si NPs further polymerizes withco-monomer to produce Si NPs-based nanocomposite films. By altering the dosage ofSi NPs, the refractive index of the films is tunable to2.3. Based on the polymerizable Si NPs, we also prepared a series of free-standing films with different weight contentsof Si NPs, and the refractive index of these self-supporting films can be continuouslyregulated in the range of1.534to1.718. And we also find that the Si NPs play a keyrole in the mechanical properties of the nanocomposites.In the fifth Chapter, a novel kind of flexible free-standing and high refractiveindex transparent paper-like materials based on graphene and silicon nanoparticleswere prepared. The flexibility paper-like materials have a high refractive index (from1.534to1.721) and good transmittance. It has great potential application as LEDencapsulant materials. On this basis, we applied these materials in the field of LEDand exhibit outstanding light output compared with the unencapsulated LEDs. Theoptical free-standing paper-like materials, which comprise a pliable base and possessa high refractive index property, may be expected to expand its applications in otheroptoelectronic devices.