高折射率及高穿透度之二氧化鈦－環氧樹脂奈米複合材料之合成與物性研究

Synthesis and Physical Properties of TiO2-Epoxy Resin Nanocomposite with High Refractive Index and High Transparency

劉獻文(Hsien-Wen Liu)

指導教授 ： 林唯芳

國立臺灣大學/工學院/高分子科學與工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02933

摘要

隨著科技的進步，發展出利用高折射率奈米粒子與高分子混摻製備有機－無機奈米複合材料之技術，此奈米複合材料除了擁有高折射率及高透明度外，更有著低熱膨脹係數、良好的熱穩定性、優秀的機械性能等，因此可作為封裝材料、光波導及光學鏡片等材料。

本研究成功以溶膠凝膠法製備粒徑低於30nm之結晶性二氧化鈦奈米粒子，並使用界面活性劑進行表面改質，使二氧化鈦能夠均勻地分散至有機溶劑中。我們討論不同改質劑對二氧化鈦在溶液狀態下的光學性質影響。

接著將表面改質的二氧化鈦與環氧樹脂摻混後製成高折射率、高穿透度的奈米複合材料。動態反應動力學的研究方面，藉由熱差微分分析儀(DSC)測量複合材料的”熱流對溫度”曲線及利用Kissinger model的理論計算，我們得知硬化反應之活化能(Ea)、反應放熱峰最大值所對應的溫度(Tp)及反應放熱量(∆H)皆隨改質二氧化鈦含量增加而下降。

光學性質研究方面，硬化後的複合材料折射率隨著二氧化鈦固含量的增加而線性上升，雖然環氧樹脂本身的折射率低，但是加入折射率高的改質二氧化鈦含量至40wt%時，奈米複合材料在波長為633nm下的折射率可由1.54提升至1.73。另外，由於改質後的二氧化鈦能均勻的分散在高分子基質中，藉由紫外光-可見光圖譜分析儀(UV-Vis spectrum)得知材料在波長範圍500-800nm時，穿透度仍達90%以上。

硬化後的奈米複合材料分別利用熱差掃描計(DSC)、熱機械分析儀(TMA)、熱重分析儀(TGA)、以及微硬度測試來分析其熱性質與機械性質。隨著改質後二氧化鈦含量的增加，材料的玻璃轉移溫度（Tg）下降且耐熱性變差；但加熱到更高溫度時，由於導入了無機粒子二氧化鈦，故殘重隨二氧化鈦含量增加而上升。

關鍵字

折射率 ； 奈米複合材料 ； 溶膠-凝膠法 ； 催化劑 ； 環氧樹脂 ； 二氧化鈦

並列摘要

Along with the evolution of technology, the fabrication of the organic-inorganic nano composite was developed by blending the nano-sized particles and the polymers.
Nanocomposites had many advantages such as high refractive index, low thermal expansion coefficient, good thermal stability, and excellent mechanical properties. The high refractive index materials can be widely used as encapsulants , optical waveguides and optical lenses, etc.

In this research, crystalline TiO2 nanoparticles with an average size smaller than 30nm were successfully synthesized via sol-gel process. After surface modification, the TiO2 nanoparticles were stabilized and well dispersed in organic solvents to form transparent TiO2 nanoparticle colloidal solutions. Through the UV-vis spectra, we studied how the surfactants influenced the optical properties of surface modified TiO2 in solution state.

Then, the surface modified TiO2 nanoparticle solutions were mixed with epoxy resin to fabricate organic-inorganic hybrid materials with high refractive index and high transparency. Differential scanning calorimetry(DSC) was used to investigate the cure kinetics of the composite. We found that the activation energy (Ea) determined in accordance to Kissinger’s method, the peak temperature of exotherm (Tp), and the heat of curing(∆H) decreased with increasing concentration of surface modified TiO2.

The refractive index of cured nanocomposite films was in the range of 1.54–1.73 at 633nm, which linearly increased with the content of TiO2 nanoparticles from 0 to 40 wt %. The transmittance of the cured nanocomposite was higher than 90% because the well dispersion of surface modied TiO2 in the polymer matrix, which avoid the effect of light scattering caused by particle aggregation.

Differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermogravimetric analysis (TGA) and microhardness tests were applied to characterize the cured nanocomposite materials.

並列關鍵字

refractive index ； nanocomposite ； sol-gel ； catalyst ； epoxy resin ； titanium dioxide

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