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Temperature and Redox‐Responsive Hydrogels Based on Nitroxide Radicals and Oligoethyleneglycol Methacrylate
Macromolecular Chemistry and Physics ( IF 2.5 ) Pub Date : 2020-02-25 , DOI: 10.1002/macp.201900550 Miriam Khodeir 1 , Sayed Antoun 2 , Evelyne Ruymbeke 1 , Jean‐François Gohy 1
Macromolecular Chemistry and Physics ( IF 2.5 ) Pub Date : 2020-02-25 , DOI: 10.1002/macp.201900550 Miriam Khodeir 1 , Sayed Antoun 2 , Evelyne Ruymbeke 1 , Jean‐François Gohy 1
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A temperature and redox‐responsive polymer hydrogel is constructed by randomly incorporating 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐methacrylate (TEMPO) stable nitroxide radicals and oligoethyleneglycol methacrylate (OEGMA) groups in a polymer network. TEMPO can be reversibly oxidized into an oxoammonium cation (TEMPO+) providing the redox‐responsive properties while the lower critical solubility temperature (LCST) of OEGMA results in temperature‐responsive properties. Since a rather low amount of di(ethylene glycol) dimethacrylate (OEGMA2) is used to chemically crosslink the polymer network, the accordingly formed hydrogels obtained after swelling with water consist of microgel particles with entangled polymer chains that are not chemically crosslinked. By varying the amount of TEMPO in the polymer network, it is demonstrated that the radical form of TEMPO aggregates into hydrophobic domains acting as physical crosslinking nodes in the hydrogels and further increasing the cohesion between microgel particles. Increasing the temperature results in two opposite effects on the solubility of TEMPO and OEGMA units. The oxidation of TEMPO into TEMPO+ also results in a deep change in the hydrogel properties since TEMPO+ units are essentially hydrophilic and do not aggregate into physical crosslinking nodes.
中文翻译：
基于一氧化氮自由基和甲基丙烯酸低聚乙二醇的温度和氧化还原响应水凝胶
温度和氧化还原响应性聚合物水凝胶是通过在聚合物网络中随机掺入2,2,6,6-四甲基-1-哌啶基氧基甲基丙烯酸酯（TEMPO）稳定的氮氧自由基和甲基丙烯酸低聚乙二醇酯（OEGMA）基团而构建的。TEMPO可以可逆地氧化成氧铵阳离子（TEMPO +），提供氧化还原响应特性，而OEGMA的较低临界溶解温度（LCST）则具有温度响应特性。由于二甲基丙烯酸二乙二醇酯（OEGMA 2）用于化学交联聚合物网络，用水溶胀后获得的相应形成的水凝胶由具有未化学交联的缠结聚合物链的微凝胶颗粒组成。通过改变聚合物网络中TEMPO的量，证明了TEMPO的自由基形式聚集到疏水域中，充当水凝胶中的物理交联节点，并进一步增加了微凝胶颗粒之间的内聚力。温度升高对TEMPO和OEGMA单元的溶解度产生两个相反的影响。TEMPO +氧化为TEMPO +还会导致水凝胶性质发生深刻变化，因为TEMPO +单元基本上是亲水性的，不会聚集到物理交联节点中。
更新日期：2020-02-25
中文翻译：
基于一氧化氮自由基和甲基丙烯酸低聚乙二醇的温度和氧化还原响应水凝胶
温度和氧化还原响应性聚合物水凝胶是通过在聚合物网络中随机掺入2,2,6,6-四甲基-1-哌啶基氧基甲基丙烯酸酯（TEMPO）稳定的氮氧自由基和甲基丙烯酸低聚乙二醇酯（OEGMA）基团而构建的。TEMPO可以可逆地氧化成氧铵阳离子（TEMPO +），提供氧化还原响应特性，而OEGMA的较低临界溶解温度（LCST）则具有温度响应特性。由于二甲基丙烯酸二乙二醇酯（OEGMA 2）用于化学交联聚合物网络，用水溶胀后获得的相应形成的水凝胶由具有未化学交联的缠结聚合物链的微凝胶颗粒组成。通过改变聚合物网络中TEMPO的量，证明了TEMPO的自由基形式聚集到疏水域中，充当水凝胶中的物理交联节点，并进一步增加了微凝胶颗粒之间的内聚力。温度升高对TEMPO和OEGMA单元的溶解度产生两个相反的影响。TEMPO +氧化为TEMPO +还会导致水凝胶性质发生深刻变化，因为TEMPO +单元基本上是亲水性的，不会聚集到物理交联节点中。
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