近年來產業及學術界對於研究高分子材料摻雜奈米粒子後，所表現出的複合材料特性，一直是個相當有趣的研究課題。其中高分子膜PVK [poly(N-vinyl carbazole)]作為配向膜的應用相當有趣，液晶分子沿著垂直於摩擦配向的方向排列，且加溫後因為微布朗運動使其配向的方向轉向平行於摩擦配向的方向。因此利用此熱效應的機制，搭配摻雜奈米粒子於PVK膜中，觀察其表現的物化性質，即為本論文研究目的。
本論文將奈米粒子POSS 摻雜入高分子膜PVK中，將其塗佈於基板表面後製成樣品並注入液晶，研究該薄膜在熱處理前後對液晶配向的影響及其光電特性。在摻雜POSS粒子的PVK膜中，我們以化學方法將POSS粒子溶入PVK膜中，改變POSS粒子在PVK膜中的濃度，或者加熱該PVK膜，用以改變POSS分子長鏈在垂直方向的密度，進而影響水平及垂直配向力之間的競爭，觀察液晶配向預傾角的變化，利用1D-Dimos套裝軟體模擬所量測的電壓-穿透曲線與實驗值作比對，用來推測液晶預傾角的結果，由實驗結果得知預傾角的調控範圍利用改變POSS濃度的方法可從0°至86°，且在預傾角固定後加熱樣品，可降低液晶預傾角，此結果可在控制液晶預傾角的技術上提供一新方法。故利用該製程，製作一pi cell，量測並分析其光電特性；該方法亦可應用於製作其他元件上，如電控可變焦式液晶透鏡等。

In recently, the research topics regarging the composite materials of the nanoparticle-doped polymer film have attracted much attention by the industrical and academic communities. Among them, the polymer film of poly(N-vinyl carbazole) (PVK) has been reported for use as a liquid crystal (LC) alignment. The mechanically rubbed PVK layer can induce a planar alignment of LCs with their director axis perpendicular to the direction of rubbing. Moreover, it is reported that the direction can be switched toward the rubbing direction by thermal treatment due to the micro-Brownian motion effect. According to the mechanism, it is motivated to study the physical and chemical properties of nanoparticle-doped PVK films before and after being thermal treatment.
This thesis studies and reports the electro-optical properties and the effect of liquid crystal LC alignment resulted from the nanoparticles POSS-doped PVK film coated onto the substrates before and after being thermal treatment. In order to mix the nanoparticle-POSS into PVK material, a solvent was used to dissolve poss/pvk compound at various concentrations. Experimentally, the density of the main chains of POSS along the derection parallel to the normal of the substrate increases with the concentration of the doped POSS, and can be reduced by thermal treatment. After being thermal treatment, the homeotropic alignment anchoring will compete with the homogeneous one to induce LC pre-tilt angles. The transmission of the sample under the application of an AC voltage was measured and fitted with the simulated results obtained by 1D-DIMOS software to acquire the pretilt angle. The formed LC pretilt angle can be controlled from 0° to 86° by changing the POSS concentration without being thermal treatment. Moreover, with thermal treatment, the generated pretilt angles can be reduced. Notably,such a mechanism is a novel approach to control the LC pretilt angles. Accordingly, a π-cell was fabricated using this approach. Its electro-optical responses and properties were measured and discussed, it is believed that such an approach has potential for uses to fabricate other devices, such as electrically tunable focusing LC lens.

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