本研究合成具光異構化特性之偶氮苯單體，並以原子轉移自由基聚合法合成兩性雙團聯共聚物poly(acrylic acid)-block-poly(6-[4- (4’-methoxyphenylazo)phenoxy]hexylmethacrylate) (PAA-b-PAzoMA)。
我們以紫外光-可見光分光光譜儀探討PAA-b-PAzoMA/PEO混摻物在不同溶劑中的光異構化行為。在中性溶劑(THF和DMF)中，PAA-b-PAzoMA進行光異構化的速率大於選擇性溶劑(水)中，因為PAA-b-PAzoMA在水溶液中會形成微胞，PAA將PAzoMA包覆在內側，由於此立體障礙，造成光異構化反應較慢。PAzoMA的莫耳分率越大，光異構化的速率越慢，因為較多的偶氮苯限制了其光異構化的空間。PEO與PAA形成氫鍵後，在中性溶劑中，偶氮苯的光異構化速率不變，在選擇性溶劑中，氫鍵只影響了微胞表面的PAA，對於內部的偶氮苯並沒有施加作用力，因此光異構化速率沒有改變。
本研究亦探討PAA-b-PAzoMA/PEO混摻物在不同溶劑中的螢光放射行為。PAA-b-PAzoMA在選擇性溶劑中的螢光放射大於中性溶劑中，因為在選擇性溶劑中PAA-b-PAzoMA以微胞形式存在，阻礙了偶氮苯的光異構化反應，提升了螢光放射。在中性溶劑中，PAA-b-PAzoMA加入PEO會增強PAA-b-PAzoMA的螢光放射，因為降低了concentration quenching的可能。在選擇性溶劑中，PAA-b-PAzoMA加入PEO則減弱螢光放射，因為PEO改變了親水/疏水性的平衡。照射紫外光之後，在中性溶劑中的PAA-b-PAzoMA/PEO混摻物螢光放射有所提升，因為順式異構物有助於螢光放射，在選擇性溶劑中的PAA-b-PAzoMA/PEO混摻物螢光放射則減弱，因為PEO改變了親水/疏水性的平衡。

Azobenzene-containing amphiphilic diblock copolymer poly(acrylic acid)-block-poly(6-[4- (4’-methoxyphenylazo)phenoxy]hexylmethacrylate) (PAA-b-PAzoMA) was synthesized by atom transfer radical polymerization. The photoresponsive behavior of PAA-b-PAzoMA/PEO blends in various solvents was characterized using UV-visible spectrophotometry. The formation of micelles of PAA-b-PAzoMA with azobenzene moieties in the core in aqueous solution cause a reduction of the photoisomerization rate. We added PEO in PAA-b-PAzoMA to form hydrogen bonding with PAA. The hydrogen bonding between PAA and PEO did not affect the organization of azobenzenes, and hence the photoisomerization rate was not changed. We also investigated the fluorescence behavior of PAA-b-PAzoMA/PEO blends in various solvents. The fluorescence of PAA-b-PAzoMA/PEO blends in a selective solvent was stronger than those in a neutral solvent because azobenzene was confined in the core of micelles and it restricted the photoisomerization. In a neutral solvent, the addition of PEO in PAA-b-PAzoMA increased the fluorescence emission because it prohibited the occurrence of concentration quenching. On the other hand, in a selective solvent, the addition of PEO in PAA-b-PAzoMA decreased the fluorescence emission, which was attributed to the hydrogen bonding between PAA and PEO that changed the hydroplilic/hydrophobic balance. After UV irradiation, the fluorescence of PAA-b-PAzoMA/PEO blends in a neutral solvent increased because the cis isomers inhibited the photoinduced electron transfer mechanism. In a selective solvent, the photoisomerization changed the hydroplilic/hydrophobic balance, and the fluorescence of PAA-b-PAzoMA/PEO blends after UV irradiation decreased.

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