本篇論文將成功利用同軸靜電紡絲技術製備出可光致變色之染料摻雜膽固醇液晶次微米纖維絲。實驗發現，在靜電紡絲過程中，聚合物濃度與溶液流速會影響到製成的纖維形態，其中包含串珠型、準連續型與溢出型三種。這三種型態中，準連續型較為實用之纖維。當聚合物濃度為17.5 wt%，且鞘層(聚合物溶液)與芯層(染料摻雜膽固醇液晶溶液)之流速比例在某特定範圍時，可成功製備出準連續形態之實用型液晶纖維，而此比例範圍會隨著外流速提升而增加。
在光控研究方面，實驗結果發現，液晶纖維絲之反射特性(反射色彩與反射率)可由連續照射紫外與藍光作全光調控變化。當在染料摻雜膽固醇液晶次微米纖維絲樣品上照射一道弱紫外光(845µW/cm2)，較低濃度之偶氮親手性分子由於trans-cis同素異構反應從棒狀trans態轉變至彎曲狀cis態進而局部擾動液晶秩序性，在尚無能力破壞螺旋結構下，造成膽固醇液晶螺距之拉伸，達到可光致液晶纖維反射顏色從藍色紅移至綠色。實驗亦發現纖維絲反射色彩繼續照射藍光後藍移回藍色，此乃由於照射藍光會引發cis-trans逆同素異構反應，偶氮親手性分子會從彎曲狀cis態回復至棒狀trans態，使得纖維內膽固醇液晶螺距回復。此外，直徑較粗的液晶纖維在照射相同時間之等強度紫外光後，因含有較高cis濃度，導致變色後所需回復時間較長。進一步，若照射紫外光強度提高三倍至2.75mW/cm2，由於引致的同素異構化反應劇烈許多，所產生的大量cis態偶氮親手性分子足以劇烈擾亂膽固醇液晶結構，導致液晶纖維絲反射色彩消失變暗；此外，直徑較細與較粗的液晶纖維在照射強紫外光後，因內部侷限強度與殘留的cis異構物濃度之差異，當照射藍光回復時，形成缺陷的情況亦有所不同。由上可知，此可光控液晶纖維絲可應用於紫外線感測元件與可穿戴式智能布料。

This thesis successfully develops photo-controllable, colorful DDCLC sub-micron fibers through the coaxial electrospinning technique. Experimental results show that different polymer concentrations and feeding rates of the polymer solution and DDCLC can significantly cause different morphologies (appearances) of the formed fibers, including beading, quasi-continuous, and smearing-out types. Among these types, quasi-continuous LC fibers are practical for further application. Quasi-continuous fibers can be successfully fabricated at a polymer concentration of 17.5 wt% and specific ranges of ratio for the feeding rates of sheath (polymer solution) to core (DDCLC).
Furthermore, the experimental results show that the reflective features (i.e., reflective color and reflectivity) can all be optically controlled by successive UV- and blue beam-irradiation. With the weak UV-irradiation (845 µW/cm2), only a few azo-chiral molecules become bended cis form through trans-cis isomerizations. As a consequence, the local order parameter of LCs may slightly decrease, thus extending the helical pitch of CLC without distorting the helical axis in the fibers. This condition results in the red-shift of the reflective color of LC fibers from blue to green. With the blue beam-irradiation following UV-irradiation, the cis isomers may revert to the rod-like trans state, resulting in the recovery of the helical pitch of the CLC in the fiber cores. The color of the fibers then blue-shifts back. Under the same conditions of UV-irradiation, if the fibers are thicker, the recovery time becomes longer because of the higher concentration of induced cis isomer. If the intensity of the UV-irradiation is enhanced to 2.75 mW/cm2, the induced massive cis isomers can also considerably disturb the helical structure of the CLC in the cores, thus eliminating the color reflectivity of the fibers. More defects remain in the thicker fibers after the blue beam-irradiation-induced recovery under the same conditions of UV and blue beam-irradiation. This condition is caused by the discrepancies between the confinement strengths and concentration of the residual cis isomer in thicker and thinner fibers. Based on the results, the optically controllable LC fibers have high potential for use in applications of UV micro-sensors and wearable smart textiles.

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