Preparation Of Cellulose Nanocrystals/metal/Dielectric Hybrid Materials And Study Its Properties

The cellulose nanocrystals (CNC), nano-metals hybrid and silica dielectric compositestructure nanomaterials are an emerging class of new materials. Dispersibility cellulosenanocrystal is prepared by a high pressure homogenizer. Then the CNC as a template inducessilica rods hybrids during the TEOS (Tetracethyl orthosilicate) hydrolysis process. The siliconcarbide whisker can be obtained by high temperature calcination for hybrids. The modifiedsilica and polystyrene microspheres as the matrix, the surface coats or deposits nano-silver,and the fluorescent dyes can be coated on the dielectric silica spheres. The hybrids have thedifferent functions, such as the multifunctional characteristics of metallic silver and themultifunctional characteristics of the fluorescent dyes. Therefore such hybrid materials arewidely used in the polymer matrix enhanced, antimicrobial, surface-enhanced Ramanscattering and biomedical field. This study reports that cellulose nanocrystals, silicon carbidewhiskers, nano-structure of hybrids hybrids (Ag/SiO2,Ag/CNC and Ag/PS) and fluorescentmaterial dye-doped silica hybrid compounds are prepared. The properities of polymerreinforce, fluorescently labeled performance, surface-enhanced Raman and antimicrobial arealso discussed. The paper is divided into five chapters.In the first chapter, the overview research significance and purpose of the hybrids structuralmaterials are given. And the commonly used preparation method, basic properties, applicationareas, our study thesis, main content and innovation are given.In the second chapter, the CNC is prepared by physical and mechanical method (highpressure homogenization method), and refinement of the low melting point glass powder arealso obtained by the same way. We discuss different homogenization time for effectingcellulose and glass powder particle size. The preparation CNC has a rod like and a gooddispersibility. And the particle diameter of glass powder reduces before than homogeneoussignificantly by the same method. After high homogeneous, the sintering temperature andsoftening of the glass powder are also studied. The result showes that the smaller the particlesize of the glass powder, the sintering temperature and the softening temperature is lower.In the third chapter, the cellulose nanocrystals as a template and inducers can form rod like hybrid materials during the TEOS hydrolysis process. The silicon carbide is obtainedhigh-temperature calcination the hybrid materials. We also test the silicon carbide whiskestructure by XRD, TEM, FTIR and so on. The silicon carbide whisker is applied polystyreneresin reinforced. And compared to ordinary polystyrene, the mechanical properties of siliconcarbide whisker-reinforced resin is significant improvement which the tensile strengthincreased by3times, notched impact strength increased by about8times. It shows that thesynthesis SiC whiskers have broad application prospects in polymer-based areas.In the fourth chapter, the modified silica as matrix, Fe3+as catalyst and DMF as a reducingagent, we prepare high dispersion Ag/SiO2hybrids. The catalyst and the reaction temperaturealso discussed for Ag nanoparticles deposited. The silver nanoparticles coating SiO2is usedin antibacterial test, and it also showes excellent antibacterial properties. Another fluorescentdye doping in the modified SiO2nanospheres is synthesized. The nanocomposites have gooddispersion, uniform size and the particle size between50～80nm. The fluorescence testexperiments show that the nanocomposites still retain the performance of the originalfluorescent and fluorescent leak can be significantly improved. We find that the cells have thedye doping silica nanocomposites when the nanocomposites are applied to cell label.In the fifth chapter, we prepare monodisperse polystyrene microspheres. And the obtainedPS spheres as a matrix, the nanocrystalline silver deposite different charges in PSmicrospheres surface. The Ag/PS composites are used in SERS enhancement experiments andit can improve MB’s Raman signals. In addition, by the simple ultrasound method, we canobtain nano-silver deposited CNC surface. It find that the growth of nano-silver particlesincrease with ultrasonic reaction time. With ultrasonic reaction60min, the uniform size of thenano-silver can deposit CNC surface. When ultrasonic time is80min, nano silver becomeslarger, and nano silver is obvious agglomeration and uneven in size. Further application ofantibacterial experiments, the nanosilver deposited CNC composites show good antibacterialeffect. And this material can be applied to antibacterial and biomedical research field.