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Stimuli-responsive dendronized polymeric hydrogels through Schiff-base chemistry showing remarkable topological effects†
Polymer Chemistry ( IF 4.1 ) Pub Date : 2017-12-19 00:00:00 , DOI: 10.1039/c7py01865g Jie Liu 1, 2, 3, 4, 5 , Xiacong Zhang 1, 2, 3, 4, 5 , Xiao Chen 1, 2, 3, 4, 5 , Liangliang Qu 6, 7, 8, 9 , Liyuan Zhang 6, 7, 8, 9 , Wen Li 1, 2, 3, 4, 5 , Afang Zhang 1, 2, 3, 4, 5
Polymer Chemistry ( IF 4.1 ) Pub Date : 2017-12-19 00:00:00 , DOI: 10.1039/c7py01865g Jie Liu 1, 2, 3, 4, 5 , Xiacong Zhang 1, 2, 3, 4, 5 , Xiao Chen 1, 2, 3, 4, 5 , Liangliang Qu 6, 7, 8, 9 , Liyuan Zhang 6, 7, 8, 9 , Wen Li 1, 2, 3, 4, 5 , Afang Zhang 1, 2, 3, 4, 5
Affiliation
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Hydrogels with dual-responsive and self-healing properties were prepared through Schiff-base chemistry from oligoethylene glycol (OEG)-based dendronized copolymers. These copolymers were comprised of 88–94% dendritic OEG components to provide thermoresponsiveness and 6–12% amino moieties for crosslinking with dialdehydes. To examine the architectural effect of the dendritic polymers on the formation and performance of the hydrogels, copolymers with linear OEG pendants of similar compositions were prepared. These hydrogels inherited the thermoresponsive properties from their parent OEG-based dendronized copolymers, and their thermally induced phase transition behavior as well as reversible sol–gel transitions mediated by pH were examined. Moreover, the dynamic covalent nature of the imine bond affords the hydrogels with adaptive self-healing properties without applying any extra stimulus. Most interestingly, by virtue of the enhanced Schiff-base reaction through either thermally induced polymer aggregation or freezing of polymer aqueous solutions, hydrogels were also prepared above the polymers’ cloud points (Tcs) or below the freezing points (Tfs) of the aqueous solutions, respectively. Hydrogels with different mechanical properties and porous structures were obtained accordingly, and exhibited different thermally induced shrinking behavior. The present work not only provides a convenient strategy for the preparation of novel hydrogels with unique multi-responsive and self-healing ability from dendritic polymers with the aid of Schiff-base chemistry, but also proves that crowding and thickness effects from dendronized polymers can make a significant contribution to the formation of hydrogels and lead to the enhancement of their mechanical strength.
中文翻译：
通过席夫碱化学反应产生刺激的树突化聚合物水凝胶，显示出显着的拓扑效应†
通过基于低聚乙二醇（OEG）的树枝状共聚物的席夫（Schiff）基化学制备具有双重响应和自愈特性的水凝胶。这些共聚物由88-94％的树枝状OEG组分组成，可提供热响应性，并具有6-12％的氨基与二醛交联。为了检查树枝状聚合物对水凝胶的形成和性能的结构影响，制备了具有相似组成的线性OEG侧基的共聚物。这些水凝胶继承了其母体OEG基树枝状共聚物的热响应特性，并检测了其热诱导的相变行为以及pH介导的可逆溶胶-凝胶转变。而且，亚胺键的动态共价特性使水凝胶具有自适应的自我修复特性，而无需施加任何额外的刺激。最有趣的是，由于通过热诱导的聚合物聚集或聚合物水溶液的冻结增强了席夫碱反应，还可以在聚合物的浊点以上制备水凝胶（T c s或低于水溶液的冰点（T f s）。因此获得了具有不同机械性能和多孔结构的水凝胶，并表现出不同的热诱导收缩行为。本研究不仅为利用希夫碱化学技术从树枝状聚合物制备具有独特的多反应性和自愈能力的新型水凝胶提供了便利的策略，而且证明了由树枝状聚合物形成的拥挤和厚度效应可以使对水凝胶的形成有重大贡献，并导致其机械强度的提高。
更新日期：2017-12-19
中文翻译：
通过席夫碱化学反应产生刺激的树突化聚合物水凝胶，显示出显着的拓扑效应†
通过基于低聚乙二醇（OEG）的树枝状共聚物的席夫（Schiff）基化学制备具有双重响应和自愈特性的水凝胶。这些共聚物由88-94％的树枝状OEG组分组成，可提供热响应性，并具有6-12％的氨基与二醛交联。为了检查树枝状聚合物对水凝胶的形成和性能的结构影响，制备了具有相似组成的线性OEG侧基的共聚物。这些水凝胶继承了其母体OEG基树枝状共聚物的热响应特性，并检测了其热诱导的相变行为以及pH介导的可逆溶胶-凝胶转变。而且，亚胺键的动态共价特性使水凝胶具有自适应的自我修复特性，而无需施加任何额外的刺激。最有趣的是，由于通过热诱导的聚合物聚集或聚合物水溶液的冻结增强了席夫碱反应，还可以在聚合物的浊点以上制备水凝胶（T c s或低于水溶液的冰点（T f s）。因此获得了具有不同机械性能和多孔结构的水凝胶，并表现出不同的热诱导收缩行为。本研究不仅为利用希夫碱化学技术从树枝状聚合物制备具有独特的多反应性和自愈能力的新型水凝胶提供了便利的策略，而且证明了由树枝状聚合物形成的拥挤和厚度效应可以使对水凝胶的形成有重大贡献，并导致其机械强度的提高。
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