Stretchable and transparent hydrogels as soft conductors for dielectric elastomer actuators

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 52; no. 16; pp. 1055 - 1060
• Main Authors: Chen, Baohong, Bai, Yuanyuan, Xiang, Feng, Sun, Jeong-Yun, Mei Chen, Yong, Wang, Hong, Zhou, Jinxiong, Suo, Zhigang
• Format: Journal Article
• Language: English
• Published: Hoboken, NJ Blackwell Publishing Ltd 15.08.2014; Wiley; Wiley Subscription Services, Inc
• Subjects: Actuators; Applied sciences; Conductors; Deformation; dielectric elastomer; Dielectrics; Elastic deformation; Elastomers; Exact sciences and technology; hydrogel; Hydrogels; ionic conductor; Mathematical models; Organic polymers; Physicochemistry of polymers; Properties and characterization; Solution and gel properties; stretchable conductor; Deformation; Electrical properties; Lithium chloride; Ionic conductivity; Elastomer; Polymer solid electrolyte; Experimental study; Modeling; Colloidal gel; Free radical polymerization; dielectric elastomer; stretchable conductor; hydrogel; ionic conductor; Size effect; Acrylamide polymer; Manufacturing; Electric field effect; Actuator
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.23529

ABSTRACT A soft ionic conductor can serve as an artificial nerve in an artificial muscle. A polyacrylamide hydrogel is synthesized containing a hygroscopic salt, lithium chloride. Two layers of the hydrogel are used as ionic conductors to sandwich a dielectric elastomer and fabricate a highly stretchable and transparent actuator. When the two layers of the hydrogels are subject to a voltage, the actuator reduces its thickness and expands. An areal strain of 134% is demonstrated. The voltage‐strain curves are calculated by using a model that accounts for the elastic constraint of the hydrogel and the inhomogeneous deformation of the actuator. For actuators fabricated with the hydrogel of various thicknesses and with the dielectric elastomer of various prestretches, excellent agreements are found between experimental data and theoretical predictions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1055–1060 Elastomeric conductors are being intensely researched for their potential applications in soft actuators, robotics, and generators. A polyacrylamide hydrogel containing a hygroscopic salt, lithium chloride, is synthesized as a stretchable transparent ionic conductor, and is laminated with a dielectric elastomer to make a largely deformed actuator. The elastic constraint of the hydrogel and the deformation of actuator are studied by an inhomogeneous model. The experimental results and the theoretical predictions are highly consistent.