Stimuli-responsive structures find use in many areas of technology, ranging from soft robotics to biomimetic structures. Drawing inspiration from biologic materials a recent interest in polymer composites has centered around the ability to combine hydrophobic (elastomer) and hydrophilic (hydrogel) materials. While previous research has utilized chemical approaches to generate strong adhesion between hydrogels and elastomers, herein a more general methodology is presented. This talk will focus on the production of hydrogel/elastomer composites based on a physical adhesion approach (i.e., a fabric interphase) and the composite application as stimuli-responsive actuators. In our method, a glass fiber fabric is implemented as an interfacial compatibilizer between a polyampholyte hydrogel and an elastomer; this composite structure results in a tearing toughness (143 kJ m<sup>-2</sup>) which vastly exceeds the toughness of either neat soft component. We use this approach to demonstrate stimuli-responsive curvature throughout the entire composite structures when exposed to organic solvents, salt solutions, or vacuum. Notably, we demonstrate cyclic actuation which demonstrates tension intensities ~ 20% that of human skeletal muscle. Experimental results are qualitatively and quantitatively compared with Timoshenko modeling exhibiting excellent agreement. The method presented within this talk merges the benefits of fabric-reinforced composites and hydrogel/elastomer composites to produce robust soft materials with wide applicability. Being able to produce robustly bound hydrogel/elastomer composites with various stimuli-responsive actuation mechanisms and a cyclic nature lends to a wide range of applications, such as artificial muscles, demonstrated here.

Stimuli-responsive hydrogel/elastomer composites via fabric interphases

2019 Spring National Meeting

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