Synthesis,self-assembly,and photomechanical actuator performance of a sequence-defined polyviologen crosslinker |
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Authors: | Abigail O Delawder Anusree Natraj Nathan D Colley Tiana Saak Angelique F Greene |
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Institution: | Department of Chemistry, Washington University, St. Louis, MO, USA |
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Abstract: | ABSTRACTAlthough 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. |
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Keywords: | Redox-responsive materials viologens macrocrosslinker photoredox catalysis |
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