Rugged Soft Robots using Tough, Stretchable, and Self‐Healable Adhesive Elastomers

Abstract

Soft robots are susceptible to premature failure from physical damages incurred within dynamic environments. To address this, we report an elastomer with high toughness, room temperature self‐healing, and strong adhesiveness, allowing both prevention of damages and recovery for soft robotics. By functionalizing polyurethane with hierarchical hydrogen bonds from ureido‐4[1H]‐pyrimidinone (UPy) and carboxyl groups, high toughness (74.85 MJ m−3), tensile strength (9.44 MPa), and strain (2340%) can be achieved. Furthermore, solvent‐assisted self‐healing at room temperature enables retention of high toughness (41.74 MJ m−3), tensile strength (5.57 MPa), and strain (1865%) within only 12 h. The elastomer possesses a high dielectric constant (≈9) that favors its utilization as a self‐healing dielectric elastomer actuator (DEA) for soft robotics. Displaying high area strains of ≈31.4% and ≈19.3% after mechanical and electrical self‐healing, respectively, the best performing self‐healable DEA is achieved. With abundant hydrogen bonds, high adhesive strength without additional curing or heating is also realized. Having both actuation and adhesive properties, a “stick‐on” strategy for the assembly of robust soft robots is realized, allowing soft robotic components to be easily reassembled or replaced upon severe damage. This study highlights the potential of soft robots with extreme ruggedness for different operating conditions.

A Data‐Driven Review of Soft Robotics

“…[485] Recent publications following our data collection have described progress in the 3D printing of elastomers for streamlined fabrication, [486,487] and further development has occurred in self-healing elastomers that are combined with liquid metals or adhesives. [487,488] Cui et al even crafted garments made from bulk elastomeric material for thermoregulation of an individual to reduce environmental impacts. [489] A widely adopted category, elastomers show great diversity in chemical makeup, application, and function media.…”

Probing and Manipulating Noncovalent Interactions in Functional Polymeric Systems

“…Strategies such as adding a high concentration of hygroscopic LiCl salt or wrapping the hydrogels with an elastomer as an outer layer have been proposed, but they are either expensive or complicated. Therefore, the development of water-free self-healing elastomers has become a promising strategy. − For example, bidentate urea hydrogen bonds, urethane hydrogen bonds, bidentate carboxylated hydrogen bonds, and quadruple hydrogen bonds between UPy moieties have been extensively studied for the fabrication of self-healing elastomers toward applications in flexible electronics such as soft robots, e-skin, triboelectric nanogenerators, capacitive sensors, etc. A major challenge for the preparation of self-healing hydrogels based on hydrophobic interactions is the poor solubility of hydrophobic monomers in aqueous solutions, which could be addressed by the formation of micelles or controlled dehydration.…”

Adhesive and Self-Healing Polyurethanes with Tunable Multifunctionality

“…Secondly, antioxidant and anti-inflammatory properties appear critical, which can stabilize the normal physiological microenvironment and facilitating tissue recovery at the implantation site [ 12 , 13 ]. Since implants are easily damaged by mechanical and chemical external stresses to result in reduced service life and loss of function during their lifetime [ 14 , 15 ], self-repairing properties can allow for functional recovery and prolong the implant life [ 16 , 17 ]. In addition, extensive and adequate adhesion to the substrate, especially in wet media, is important to ensure the stable performance of implants [ 18 ], when PUs are used as a coating [ 19 , 20 ].…”