Of the multitude of stimuli-responsive microgels, it is still a challenge to achieve multiple responsivenesses to one single stimulus, which can even revert to the corresponding original state autonomously after stimulus. In this work, we reported a series of anthraquinone functionalized microgels (PNI-xVAQ) with thermosensitivity and redox-actuated self-regulating color, size, and fluorescent properties, which were easily synthesized via surfactant-free emulsion copolymerization (SFEP) with N-isopropylacrylamide (NIPAm) as the monomer, 2-vinylanthraquinone (VAQ) as the comonomer, and N,N′-methylenebis(acrylamide) (BIS) as the cross-linker in an aqueous solution at 70 °C. The hydrophobic interactions of comonomer VAQ also led to the formation of internal phase-separated hydrophobic nanodomains in the obtained PNI-xVAQ microgels. The self-regulating color, size, and fluorescence changes of the PNI-xVAQ microgels were reliant on the nonequilibrium redox process of anthraquinone moieties by the addition of sodium dithionite as the chemical fuel to activate the positive feedback that was the reduction of anthraquinone to transient anthraquinone radical anions, following the slow oxidation of anthraquinone radical anions by autonomous “breathing” oxygen in air as the delayed negative feedback. These autonomous self-regulating properties of the PNI-xVAQ microgel were recyclable to a certain extent by repeated feeding of sodium dithionite.

中文翻译：

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具有相分离的纳米域和通过结合蒽醌部分的自我调节特性的多响应微凝胶。

在多种刺激响应性微凝胶中，实现对单个刺激的多种响应仍然是一项挑战，在刺激后，这些响应甚至可以自动回复到相应的原始状态。在这项工作中，我们报道了一系列具有热敏性和氧化还原激活的自调节颜色，大小和荧光性质的蒽醌官能化微凝胶（PNI- x VAQ），可通过无表面活性剂与N的乳液共聚（SFEP）轻松合成-异丙基丙烯酰胺（NIPAm）作为单体，2-乙烯基蒽醌（VAQ）作为共聚单体，N，N在70°C的水溶液中，以'-亚甲基双（丙烯酰胺）（BIS）作为交联剂。共聚单体VAQ的疏水相互作用也导致在获得的PNI- x VAQ微凝胶中形成内部相分离的疏水纳米域。PNI- x VAQ微凝胶的自调节颜色，大小和荧光变化取决于蒽醌部分的非平衡氧化还原过程，方法是添加连二亚硫酸钠作为化学燃料来激活正反馈，即将蒽醌还原为瞬态蒽醌自由基阴离子，随后通过自主“呼吸”空气中的氧气作为延迟的负反馈缓慢氧化蒽醌自由基阴离子。PNI- x的这些自主的自我调节特性VAQ微凝胶可通过重复加入连二亚硫酸钠在一定程度上可回收利用。