高分子安定藍相液晶之晶格結構與電壓響應研究

Abstract

液晶的藍相介於各向等性相及膽固醇相之間，且有特殊的晶體對稱性結構；藉由加入高分子單體並進行光聚合作用後，可形成高分子聚合物網絡以穩定液晶的藍相結構，即為高分子安定藍相液晶；且藍相液晶的克爾效應(Kerr effect)，可應用於顯示器上。 本論文中分別對下列幾項主題進行研究：1.對高分子單體濃度比例的改變，並找出濃度比例對電壓響應的關係；2.不同基板與不同邊界條件對藍相液晶的影響；3.高分子單體配方對藍相液晶反射光譜的影響。本論文最後成功的根據反射光譜與科索圖案(Kossel diagrams)的量測，確定了藍相液晶的晶體結構與晶格常數。並使用場發式掃瞄電子顯微鏡(FESEM)直接觀察高分子網絡的鍵結，其高分子聚合物的尺寸亦落在晶格常數的合理範圍內。

Blue phase liquid crystal (BPLC) is a liquid crystal phase between cholesteric phase and isotropic phase. In the blue phase, two crystal structures, the body-centered cubic and the simple cubic, can be observed. By mixing BPLC with monomers and polymerizing this mixture, the polymer networks would locate at the disclination lines of the BPLC and stabilize the BPLC, forming the “polymer stabilized blue phase liquid crystal (PSBPLC)”. And, the Kerr effect of BPLC could be used in display technology. This research be divided as the following parts: 1. the relationship between monomer concentrations of BPLC and voltage response; 2. the effects of substrates and different boundaries on BPLC; 3. the effects of monomer recipes on BPLC. By using reflective spectra and Kossel diagrams of the BPLC, the crystal structure and the lattice constant of BPLC are determined. Furthermore, the morphology of the polymer networks in PSBPLC was directly observed by using the Field Emission Scanning Electron Microscopy (FESEM). The FESEM images reveal that the polymer networks are consistent with KiKuchi’s model.