Photoresponsive hydrogel system using molecular recognition of α-cyclodextrin
Photoresponsive hydrogel system using molecular recognition of α-cyclodextrin
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DOI：
10.1021/ma050670v
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发表时间：
2005-06-14
期刊：
影响因子：
5.5
通讯作者：
Harada, A
中科院分区：
文献类型：
--
作者：
Tomatsu, I;Hashidzume, A;Harada, A
通过对α-环糊精(α-CD)的分子识别，我们成功地构建了由简单组分、α-CD、十二烷基(C-12)修饰的聚丙烯酸(p(AA/C-12))和竞争客体4，4‘-偶氮二苯甲酸(ADA)组成的光响应性水凝胶体系。P(AA/C-12)的水溶液表现出类凝胶行为，因为聚合物链通过C-12侧链的疏水缔合形成网络结构。当α-CD加入到凝胶状水溶液中时，由于α-CD与C-12侧链形成包合物，解离了C-12侧链的疏水相互作用，凝胶转变为溶胶混合物。在p(AA/C-12)和α-CD的二元溶胶混合物中加入ADA后，α-CD主要与ADA相互作用，然后恢复C-12侧链的疏水缔合，导致溶胶-凝胶转变。当P(AA/C-12)、α-CD和ADA的三元凝胶混合物在紫外光照射下，ADA从反式异构化为顺式时，由于α-CD比顺式-ADA更有利于与C-12侧链形成包合物，混合物发生了凝胶-溶胶转变。当三元溶胶混合物在可见光照射下，ADA从顺式异构化为反式时，混合物经历了溶胶-凝胶转变。此外，在紫外光和可见光的重复照射下，这些凝胶到溶胶和溶胶到凝胶的转变反复发生。
Using molecular recognition of a-cyclodextrin (alpha-CD), we have successfully constructed a photoresponsive hydrogel system by combination of simple components, a-CD, dodecyl (C-12)-modified poly(acrylic acid) (p(AA/C-12)), and a photoresponsive competitive guest, 4,4'-azodibenzoic acid (ADA). An aqueous solution of p(AA/C-12) exhibited a gel-like behavior because polymer chains form a network structure via hydrophobic associations Of C-12 side chains. When alpha-CD was added to the gel-like aqueous solution, the gel was converted to a sol mixture because hydrophobic interactions Of C-12 side chains were dissociated by the formation of inclusion complexes of alpha-CD with C-12 side chains. Upon addition of ADA to a binary sol mixture of p(AA/C-12) and alpha-CD, alpha-CD interacted predominantly with ADA, and then hydrophobic associations of C-12 side chains were restored, resulting in a sol-to-gel transition. When a ternary gel mixture of P(AA/C-12), alpha-CD, and ADA was irradiated with UV light, ADA was isomerized from trans to cis, and the mixture underwent a gel-to-sol transition because alpha-CD formed inclusion complexes more favorably with C-12 side chains than with cis-ADA. When the ternary sol mixture was irradiated with visible light, ADA was isomerized from cis to trans and the mixture underwent a sol-to-gel transition. Furthermore, these gel-to-sol and sol-to-gel transitions occurred repeatedly by repetitive irradiations of UV and visible light.