液晶聚合物薄膜之表面物理研究及應用開發

Abstract

本論文主要欲探討可電控表面水濕性之液晶聚合物薄膜(Liquid Crystal and Polymer Composite Film)其表面物理機制及相關應用包含光電元件及精蟲感測元件之開發。此液晶聚合物薄膜可電控表面親疏水特性之原理，主要是利用液晶與聚合物單體之相分離，造成液晶錨定於表面聚合物顆粒之間，因液晶之苯環面及末端基的氰基鏈具不同的親疏水特性，當施加電場可使液晶指向矢軸向改變，因而液晶聚合物薄膜表面水濕性可用電場調控。本論文由液晶與聚合物單體之相分離出發，討論液晶聚合物薄膜相分離後的表面型態對於其表面電控水濕性之影響，並探討液晶聚合物薄膜表面接觸角遲滯效應對液滴運動之效應，並提出液晶聚合物薄膜之表面理論模型，由實驗及理論方式也找出了液晶聚合物薄膜隨電場變化之表面張力，由實驗結果及理論探討可同時驗證液晶指向矢軸向的改變對表面張力之影響。由表面理論衍生，我們實現許多光電與生醫應用包括利用液滴伸縮之不需偏振片的顯示器及精蟲檢測器。此論文研究可幫助設計開發更多生醫感測元件及光電元件：如三酸甘油酯感測器、血液感測器、光電開關等。

The surface physics and the applications of a switchable surface, liquid crystal and polymer composite film (LCPCF), are investigated in this thesis. The surface of LCPCF consisting of polymer grains and liquid crystal (LC) directors anchored among the polymer grains is electrically switchable after photo-induced phase separation because the benzene plane and cyano-group of LC molecules have different wetting properties. In this thesis, to begin with the phase separation between LC and polymer, we study wettability of LCPCF with different surface morphologies and droplet manipulation on LCPCF affected by contact angle hysteresis. The surface physical model of LCPCF is developed. The surface tension of LCPCF under different external voltages is also analyzed. On the basis of theoretical model and experiments, the orientation of LC directors indeed affects surface tension of LCPCF. Moreover, two applications are developed as well: one is a stretching type polarizer-free display and the other is sperm tester. This study can assist developing more photonic devices and biosensors, such as electro-optical switches, triglycerides sensors, and blood sensors.