An embedded interface regulates the underwater actuation of solvent-responsive soft grippers

Area of Science:

• Polymer Science
• Materials Science
• Soft Robotics

Background:

• Bilayer polymer systems offer tunable actuation for various applications.
• Interface properties significantly influence the mechanical behavior of composite materials.
• Solvent-induced deformation is a key mechanism for soft actuators.

Purpose of the Study:

• To investigate the role of interfacial strength in the folding and actuation of polymer bilayers.
• To understand how interface properties affect solvent-responsive deformation and gripping capabilities.
• To develop a model correlating interface strength with bilayer performance.

Main Methods:

• Fabrication of chitosan/Poly(methyl-methacrylate) (PMMA) bilayers with varying interfacial strengths.
• Experimental characterization of bilayer folding and actuation in response to solvent exposure.
• Development and application of a coupled diffusion-deformation and cohesive zone model.

Main Results:

• Interfacial strength was successfully tuned by silane treatment, affecting bilayer folding dynamics.
• A direct correlation was observed between interface strength and the direction, curvature, and rate of folding.
• The developed model accurately predicted the observed diffusion-deformation behavior.

Conclusions:

• Interfacial strength is a critical parameter controlling the solvent-induced actuation of polymer bilayers.
• The study demonstrates the potential of these bilayers as grippers for submerged objects, triggered by the immersion medium.
• This work provides fundamental insights into designing responsive soft actuators based on interfacial engineering.