J. Bao, J. Yang, D. Fan
The University of Texas at Austin,
United States
Keywords: hierarchical organogels, bicontinuous networks, phase separation, mechanical enhancement
Summary:
Hydrogels and organogels, comprising three-dimensional polymer networks swollen with water and organic solvents respectively, have garnered significant attention due to their high liquid content, softness, and biocompatibility. However, their widespread application remains constrained by inherent mechanical limitations. Drawing inspiration from biological tissue networks such as tendon, muscle, and bone, where self-assembled fibrous nanostructures synergistically interact with non-fibrillar organic matrices to facilitate efficient load distribution and energy dissipation, we herein report a type of hierarchical organogels with bicontinuous networks. These networks are engineered through the combination of phase-separated poly(vinyl alcohol) (PVA) interconnected by in-situ polymerized poly(acrylic acid) (PAA) in organic solvents. Through integrated molecular and structural engineering approaches, we have successfully created organogels featuring multiscale double-network architecture, wherein phase-separated polymer-rich domains serve as primary energy-dissipative networks, while solvent-rich regions facilitate load distribution and accommodate substantial deformations. The resultant organogels demonstrate exceptional mechanical properties, including an ultimate stress of 31.2 MPa, toughness of 410 MJ/m³, remarkable stretchability up to 3100%, and superior long-term stability. Molecular dynamics simulations elucidate the crucial role of PVA-PAA interactions in organic solvents during deformation processes. The versatility of this synthesis strategy has been validated across various solvent systems and monomers, demonstrating broad applicability across different polymer platforms. These robust organogels present promising opportunities for applications in tissue engineering, wearable electronics, soft robotics, and energy storage devices, while offering substantial potential for further functional optimization.