Shuhe Wei,Yan Xiao,Hanwen Jiang,Frédéric Héraly,Liangshun Zhang,Wanyi Huang,Jiayin Yuan,Meidong Lang
Soft actuators capable of large and swift locomotion in combination with biocompatibility hold great potential in medicine and healthcare applications. In this contribution, a polypeptide-type poly(ionic liquid) (termed “PLL-PMIM-Tf 2 N”) was designed and synthesized by post-polymerization modification of poly- L -lysine; Next, via controlled electrostatic complexation with poly(acrylic acid) (PAA) or poly( L -glutamic acid) (PLG), porous membrane actuators termed PLL-PMIM-Tf 2 N/PAA or PLL-PMIM-Tf 2 N/PLG, respectively, were tailor-made. Hemolytic tests support excellent blood cell compatibility of the fully polypeptide-based PLL-PMIM-Tf 2 N/PLG actuator. The as-made soft actuators could bend significantly up to 500°with a maximum curvature of 7 cm −1 in response to solvent vapor in a fast actuation process within 2 s. Their high sensitivity towards solvent molecules equips them with skills to distinguish solvent isomers, as exemplified by butanol isomers, in terms of bending curvature due to varied molecular interactions between the actuator and the isomer. To be highlighted is an unusual irreversible actuated tubular state of the fully polypeptide-based PLL-PMIM-Tf 2 N/PLG actuator that is stable in shape and resembles bionic blood vessels. Such polypeptide-type poly(ionic liquid) actuators are of significant value in future development of biocompatible devices for medical and healthcare applications.
Yang Cong,Shuhui Liu,Fengxiang Wu,Hua Zhang,Jun Fu
Rapid and reversible actuation and shape memory effects are critical for biomimetic soft actuators based on polymer hydrogels. However, most conventional hydrogel actuators show very slow actuation or deformation rates in water. It remains a challenge to realize rapid actuations, particularly for hydrogels to actuate in air. Here, a novel strategy to create diverse hydrogel devices with shape memory effects and rapid reversible actuations even in air was demonstrated. This strategy relies on a precise definition of local crosslinking by using multivalent metal ion coordination. This is demonstrated by infiltrating Fe3+ ions into stretchable nanocomposite polyacrylamide hydrogels with the amide groups converted into primary amine groups for multivalent coordination and crosslinking. The Fe3+ coordination with amine groups enhanced the crosslink density and modulus, leading to deswelling. By using an iron rod electrode, the Fe3+ coordination and crosslinking were precisely controlled to generate hydrogels with heterogeneous local crosslinking, including Janus hydrogels, S-shaped hydrogels, and cross-shaped hydrogel grippers. These soft devices were reversibly actuated in tens of seconds when cyclically dehydrated in ethanol and rehydrated in water. Most interestingly, very rapid reversible actuations of a hydrogel device in air were demonstrated by using electro-redox reaction of Fe3+ and Fe2+ in the hydrogel, where the reversible local coordination crosslinking and decomposition served as a hinge to actuate the hydrogel. This strategy based on reversible local coordination and crosslinking may open an avenue for rapid fabrication of hydrogel devices with well-defined structures and actuation properties.
危险品化学品经营许可证（带存储）