title: Programmable and Bidirectional Bending of Soft Actuators Based on Janus Structure with Sticky Tough PAA-Clay Hydrogel.
abstract: Facile preparation, rapid actuating, and versatile actions are great challenges in exploring new kinds of hydrogel actuators. In this paper, we presented a facile sticking method to prepare Janus bilayer and multilayer hydrogel actuators that benefited from a special tough and adhesive PAA-clay hydrogel. Combining physical and chemical cross-linking reagents, we endowed the PAA gel with both toughness and adhesion. This PAA gel was reinforced by further cross-linking with Fe3+. These two hydrogels with different cross-linking densities exhibited different swelling capabilities and moduli in the media manipulated by pH and ionic strength, thus acting as promising candidates for soft actuators. On the basis of these gels, we designed hydrogel actuators of rapid response in several minutes and precisely controlled actuating direction by sticking two hydrogel layers together. Elaborate soft actuators such as bidirectional bending flytrap, gel hand with grasp, open, and gesturing actions as well as word-writing actuator were prepared. This method could be generalized by using other stimuli-responsive hydrogels combined with the adhesive PAA gel, which would open a new way to programmable and versatile soft actuators.
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Jiahe
authors.initials: J
authors.lastname: Huang
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Yuancheng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Tao
authors.identifier: http://orcid.org/0000-0002-2396-377X
authors.initials: T
authors.lastname: Wang
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Weixiang
authors.identifier: http://orcid.org/0000-0001-6964-8313
authors.initials: W
authors.lastname: Sun
authors.affiliation: Research Institute of Materials Science and ‡State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tong
keywords: Janus structure; bidirectional actuation; bilayer; soft actuator; tough PAA-clay hydrogel