ABSTRACT Although it is well known that viologen radical cations can self-assemble into stacks or complexes on account of radical-radical pairing interactions, it has only recently been demonstrated that reduction of main-chain polyviologens integrated into hydrogel networks can trigger actuation. In these earlier examples, hydrogels comprising oligoethylene glycol-based polyviologens and poly(ethylene glycol) were functionalized with terminal azide groups to prepare ‘click’-based gels. Here, we report a new structural design for the functional polyviologen that consists of main-chain viologen subunits separated by hexamethylene groups instead of glycols and is capped at each end with styrene groups. Activation of this viologen-based macrocrosslinker was achieved using chemical- and photoreduction methods and its ability to undergo intramolecular chain-folding was monitored by absorption spectroscopy. Acrylate-based organogels and hydrogels were also prepared and a comparison was carried out to assess the actuator performance in each gel in terms of the rate of contraction and changes in stiffness. Graphical abstract

中文翻译：

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序列定义的聚紫精交联剂的合成、自组装和光机械致动器性能

摘要虽然众所周知紫精自由基阳离子可以由于自由基-自由基配对相互作用而自组装成堆叠或复合物，但直到最近才证明，整合到水凝胶网络中的主链多紫精的还原可以触发驱动。在这些早期的例子中，包含低聚乙二醇基聚紫精和聚（乙二醇）的水凝胶用末端叠氮化物基团官能化以制备基于“点击”的凝胶。在这里，我们报告了一种功能性聚紫精的新结构设计，它由主链紫精亚基组成，由六亚甲基基团而不是二醇分隔，并在每端用苯乙烯基团封端。这种紫罗碱基大交联剂的活化是使用化学和光还原方法实现的，并且通过吸收光谱监测其进行分子内链折叠的能力。还制备了基于丙烯酸酯的有机凝胶和水凝胶，并进行了比较，以评估每种凝胶在收缩率和刚度变化方面的致动器性能。图形概要