膽固醇型液晶為週期性螺旋結構，由於螺距約與光線波長相當，故可使特定波長之光線發生布拉格反射(Bragg reflection)；而一般膽固醇液晶的形成是將手性分子溶解於向列型液晶中，藉由摻混在向列型液晶中的手性分子來誘導出膽固醇型液晶相。本研究以高分子拓印技術複印膽固醇液晶螺旋結構，藉此高分子模板誘導出膽固醇液晶相，並使具有特殊之光學性質。利用非手性且不具有液晶相的雙官能性單體4,4’-bis(6-(acryloyloxy)hexyloxy)-biphenyl (BAHB)與膽固醇型液晶均勻混和，經光聚合誘導相分離法及溶劑洗滌的步驟後，可複印出具膽固醇型液晶分子排列的手性網狀結構，之後重新填入向列型液晶，發現可成功誘導出膽固醇液晶相，並顯示出選擇性光反射的光學特性。本研究針對雙官能性單體的含量、cell元件厚度、及多次曝光的新製程參數，探討高分子網狀結構對液晶分子的誘導能力，找出在此製程下的最佳條件。結果發現，該高分子膜內部在不含液晶條件下即具有布拉格反射之光學特性，亦可藉由充填溶劑種類的改變調控反射光之波長。

Cholesteric liquid crystal (ChLC) spontaneously forms a photonic band structure and exhibit Bragg reflections when the periodicity of helix matches the wavelength of light. It is well-known that the helical arrangement of cholesteric liquid crystals is mainly induced by the chiral molecules. In this thesis, we conceived a new methodology for preparing chiral non-liquid crystalline polymer networks with achiral liquids, which imprint cholesteric liquid crystalline structure with photonic properties. A chiral polymer template was prepared by photopolymerizing an achiral and difunctional monomer of 4,4’bis(6-(acryloyloxy)hexyloxy)biphenyl (BAHB) that was dispersed within a chiral nematic pre-mixture, which was then subsequently removed by solvent. Upon injecting the achiral nematic liquid crystal into the polymer template cell, it was found to exhibit the cholesteric liquid crystal phase and perform selective light reflection property. The effects of monomer concentration, spacer thickness and multiple photocrosslinking times on the optical properties of the polymer film were investigated. Furthermore, we found that the polymer materials themselves served not only as a chiral template but also exhibited Bragg reflections property at the optimal condition. Tuning of color was achieved by making a refractive index contrast between the two periodic media of imprinted solid helical structure and the isotropic liquids that is filled it.

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