Abstract A photoresponsive hydrogel consisting of stilbene dye (Sti; 4,4′-disubstituted stilbene), an 8-armed core molecule (POSS; polyhedral oligomeric silsesquioxane having eight amino groups), and bifunctional poly(ethylene glycol) (PEG) showed large and fast deformation derived from its highly symmetrical structure in aqueous media. The polymeric hydrogel with an 8-armed POSS (POSS-Sti; cross-linked polymer obtained from polycondensation reaction between POSS and PEG-modified Sti) showed a large deformation upon photostimulation (UV-A (λ = 350 nm) and UV-C (λ = 280 nm)). The bending deformation can be repeated at least ten times. On the other hand, the control hydrogel without Sti dye (POSS-PEG; polymer prepared from the polycondensation reaction between POSS and PEG) did not show any deformation upon photoirradiation. However, the TPEG-Sti hydrogel (Sti cross-linked with a 4-armed core molecule (TPEG; tetra-armed poly(ethylene glycol))) showed a smaller deformation compared to the POSS-Sti hydrogel with the 8-armed core molecule. The larger deformation of the POSS-Sti hydrogel was discussed in detail. The photoisomerization of the Sti units drives swelling/shrinking and the change in the Young’s modulus of the POSS-Sti hydrogel upon UV irradiation, where a stacked assembly of the Sti dye molecules acts as a cross-linking point. The photoisomerization of the Sti dye results in the association/dissociation of the Sti assembly, and the increase/decrease in the cross-linking density dramatically alters the volume of the POSS-Sti hydrogel, causing the efficient assembly of the Sti units because of their highly symmetric structure and the high density of the Sti dye derived from the 8-armed POSS core structure.

中文翻译：

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由 8 臂多面体低聚倍半硅氧烷交联的光响应聚合物致动器

摘要 由二苯乙烯染料 (Sti; 4,4'-二取代二苯乙烯)、8 臂核心分子 (POSS; 具有八个氨基的多面体低聚倍半硅氧烷) 和双功能聚乙二醇 (PEG) 组成的光响应水凝胶显示出大并且由于其在水性介质中的高度对称结构导致的快速变形。具有 8 臂 POSS（POSS-Sti；从 POSS 和 PEG 修饰的 Sti 之间的缩聚反应获得的交联聚合物）的聚合物水凝胶在光刺激（UV-A（λ = 350 nm）和 UV-C）下表现出较大的变形(λ = 280 纳米))。弯曲变形至少可以重复十次。另一方面，不含 Sti 染料的对照水凝胶（POSS-PEG；由 POSS 和 PEG 之间的缩聚反应制备的聚合物）在光照射下没有表现出任何变形。然而，与具有 8 臂核心分子的 POSS-Sti 水凝胶相比，TPEG-Sti 水凝胶（Sti 与 4 臂核心分子（TPEG；四臂聚乙二醇）交联）显示出更小的变形。详细讨论了 POSS-Sti 水凝胶的较大变形。Sti 单元的光异构化在紫外线照射下驱动了 POSS-Sti 水凝胶的膨胀/收缩和杨氏模量的变化，其中 Sti 染料分子的堆叠组装作为交联点。Sti 染料的光异构化导致 Sti 组装体的结合/解离，并且交联密度的增加/减少显着改变了 POSS-Sti 水凝胶的体积，