本研究合成具有光學異構化特性之偶氮苯單體，以具有溫度和pH值應答特性的聚甲基丙烯酸二甲氨基乙酯作為起始劑，並利用原子轉移自由基聚合法合成雙團聯共聚物poly(2-(dimethylamino)ethyl methacrylate)-block-poly(6-(4-(4-dimethylaminophenylazo)phenoxy-hexyl methacrylate) (PDMAEMA-b-PDMA-Azo)，並觀察其在不同混合溶劑比例之下結構的變化。PDMAEMA-b-PDMA-Azo在中性溶劑(THF)中為random coil結構，隨著選擇性溶劑(H2O)在混合溶劑中的比例增加時，由於PDMAEMA鏈段對水的溶解度較PDMA-Azo鏈段佳，因此會逐漸形成以偶氮苯鏈段在內、PDMAEMA鏈段在外之微胞結構。
由於團聯共聚物具有偶氮苯之光學異構化特性，因此可利用紫外光引發其構型由穩定之反式異構物轉變為順式異構物；而在置於黑暗中則會引發逆反應，使其回復至反式異構物。我們將PDMAEMA-b-PDMA-Azo分別溶於不同比例的混合溶劑(THF/H2O)中，並透過紫外光-可見光分光光譜儀分析其光異構化行為，結果顯示當水的比例增加時，團聯共聚物的聚集會限制異構化所需要的自由體積，因此光異構化的速率會下降。另外，不同比例的混合溶劑也會影響偶氮苯分子在溶劑中的聚集型態，當水的比例增加時，偶氮苯聚集型態會從nonassociation及H-aggregate逐漸轉換至J-aggregate之聚集型態，因此當水的比例增加時，其吸收圖譜之最大吸收峰會有紅移的現象。

In this study, we synthesized an azobenzene monomer with photoisomerization properties. Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), which exhibits temperature and pH-responsive behavior, was used as the initiator to synthesize the diblock copolymer poly(2-(dimethylamino)ethyl methacrylate)-block-poly(6-(4-(4-dimethylaminophenylazo)phenoxy-hexyl methacrylate) (PDMAEMA-b-PDMA-Azo) through atom transfer radical polymerization. The structural changes of the diblock copolymer in various solvent mixtures were observed. PDMAEMA-b-PDMA-Azo forms a random coil structure in a neutral solvent (THF). As the proportion of selective solvent (H2O) in the mixed solvent increases, the PDMAEMA segment, which has better solubility in water compared to the PDMA-Azo segment, gradually forms micelle structures with the azobenzene segment inside and the PDMAEMA segment outside.
Due to the photoisomerization properties of the azobenzene in the diblock copolymer, UV light can induce its configuration to change from the stable trans isomer to the cis isomer. When placed in darkness, the reverse reaction occurs, returning it to the trans isomer. PDMAEMA-b-PDMA-Azo was dissolved in mixed solvents (THF/H2O) with different ratios, and its photoisomerization behavior was analyzed using UV-visible spectrophotometer. The results showed that as the water proportion increased, the aggregation of the diblock copolymer restricted the free volume necessary for isomerization, thereby reducing the rate of photoisomerization. Furthermore, different ratios of the mixed solvents affected the aggregation states of the azobenzene molecules. As the water proportion increased, the aggregation state of azobenzene shifted from nonassociation and H-aggregate to J-aggregate. Consequently, as the water proportion increased, a red shift in the maximum absorption peak of the absorption spectrum was observed.

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