在之前的研究中，我們實驗室已經能夠成功製作出粒徑約10 nm左右的氧化鋯粒子，並藉由適當的改質有機酸及矽烷讓其能分散於酯類及醇類等極性溶劑中。藉由添加這些奈米粒子到壓克力樹酯中，我們可以提升樹酯的折射率同時保持樹酯的透光性，並能添加到約47 vol%的氧化鋯粒子而將折射率提高至1.69。這種具有高折射率且透光的樹酯膜可以應用在增亮膜(brightness enhancement for FPD)、手機面板、以及固態LED封裝等材料上。 奈米複合材料是藉由奈米粒子的添加來增加母體的性質，通常添加的粒子量越多對於性質的強化越為顯著，但是由於膠體液黏度會隨著粒子添加量的增加呈現指數性的上升，以致無法塗佈。故傳統的塗膜方式所製作出來的複合膜，其無機含量都限制在約50 vol%上下，無法有更進一步的突破。電泳沉積製程 (EPD)，是一種可解決這限制的方法。在一外加的直流電場中，膠體溶液中的膠粒會受到電場的作用往一邊的電極移動而聚集，並且有順序的堆積到電極上形成一緻密膜層，藉由此方法可以製作出具有高無機含量之奈米複合膜。本研究中，利用電泳沉積法製作出了具有高無機含量之有機無機奈米複合膜。 我們首先對實驗室過去的矽烷改質方法做了檢討，發現改質過程中不添加水，而以Non-hydrolytic反應進行的矽烷接枝是可行的。此法最大的好處是可以減少矽烷的用量並可以減少反應所需時間。接著我們驗證了經由矽烷接枝後分散的氧化鋯粒子的確具有正電性，適合進行電泳沉積製程。在此還利用了兩種不同原理的表面電位測量儀器來互相應證。最後，我們成功做出了含有82 wt%複合氧化鋯粒子、體積分率達64 vol%的連續透明複合膜。可惜因為複合粒子之折射率較低，故折射率僅能達到1.64，並建立了電泳沉積步驟的基礎參數與其所獲膜材之性質鑑定。 ;The synthesis of sub-10 nm zirconia nanocrystals, as well as the dispersion of them in polar and non-polar solvents after proper surface modification, had already been accomplished in our previous studies. By adding comparable resin to the dispersion, we could prepare a transparent composite having 47 vol% ZrO2 nanoparticles and a refractive index of 1.69. Such a high reflection index material is useful as brightness enhancement film for FPD, a simpler lens-stack for cellular phone, or a more efficient second order optical design for the LED lighting systems. The index of the ZrO2/resin composite could be increased further, by loading with more nanoparticles. This was impossible previously since the viscosity increased exponentially as the inorganic content approaching a threshold. Electrophoretic deposition (EPD) may be a way to overcome this problem. By depositing the organic modified nanoparticles at the electrode under the compression of the electric field, the particle may self-assemble into a densely-packed film on the electrode. In this study, electrophoretic deposition was used to preparing a zirconia nanoparticles/polymer composite with a high inorganic fraction. We start by substituting the previous silanes modification scheme with a non-hydrolytic one. We found that this could approach save about 20% silane and take less time to react. We also measured the zeta potential of the modified particles with two different instruments, and confirmed that they were positively charged. Finally, we successfully made a continuous transparent nanocomposite which had nearly 82 wt% / 64 vol% filler loading, and establish a guideline for controlling the properties of the EPD nanocomposite film.
