| Summary: | 博士 === 國立中央大學 === 化學工程與材料工程研究所 === 98 === The objective of this research is the preparation of high refractive index transparent nanocomposite thick film. The organic matrix of nanocomposite, epoxy resin ERL-4221 (refractive index is 1.5) is used as an encapsulant of LED. The inorganic material is selected nano-TiO2 and nano-ZrO2 which the refractive index of the two materials are higher than 2 (the refractive index of anatase-TiO2 is 2.3,compared to 2.1 for ZrO2) to enhance the refractive index of organic materials.
The primary work is the synthesis of highly dispersed TiO2 and ZrO2 nanoparticles. For high refractive index transparent nanocomposite, it is necessary to control the dispersity and crystal size of TiO2 and ZrO2. The influences of hydrolysis of precursors, pH value of neutralization and hydrothermal condition(pH, temp. and
time) in the synthesis process of highly dispersed TiO2 and ZrO2 nanoparticles were discussed.
In addition, the preparation of TiO2-ZrO2 mixed oxide was studied. The interesting was whether the advantages of TiO2 and ZrO2 nanocrystals imported for preparation of ZrTiO4 nanocrystal. ZrTiO4 nanocrystal was prepared with the coprecipitation of methacrylic acid-TiCl4 and methacrylic acid-ZrOCl2 by calcination at 600℃.
To disperse nanoparticles and epoxy resin in organic solvent, surface modification of the nanoparticles is pivotal. Surface modification of nanoparticles with oleic acid (sodium oleate), n-hexylamine (dodecylamine) or silane
(3-methacryloyloxy propyl trimethoxysilane and 3-glycidoxy propyl trimethoxysilane) allowed nanoparticles to be dispersed in n-hexane, chloroform and ethylacetate.
The MPTMS&GPTMS-modified TiO2 and ZrO2 dispersions in ethylacetate were blended with epoxy resin ERL-4221 and curing agent. The TiO2/epoxy and ZrO2/epoxy nanocomposite thick film was prepared with MPTMS&GPTMS modified
nanoparticles and epoxy resin ERL-4221 which were dispersed in ethylacetate by blade-coating and thermal curing. The thickness of TiO2/epoxy and ZrO2/epoxy
nanocomposite thick film which contained 15-45 wt% TiO2 or ZrO2 was 2-13 μm and 8-35 μm individually. The refractive index of TiO2/epoxy and ZrO2/epoxy
nanocomposite thick film was up to 1.7 and 1.63 respectively. The optical transmittance of TiO2/epoxy and ZrO2/epoxy nanocomposite thick film was higher than 80% at wavelength of 600 nm.
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