| Summary: | A new class of aqueous dual networks was studied, which incorporate both a small amount of non-covalent cucurbit[8]uril (CB[8])-mediated host-guest interactions and a trace amount of covalent cross-linking. A polymerizable guest (1-benzyl-3-vinylimidazolium), serving as a non-covalent supramolecular cross-linker upon complexation with CB[8] in a 2:1 manner is polymerized with a trace amount of chemical cross-linker N,N'-methylenebisacrylamide and a hydrophilic monomer acrylamide, yielding an aqueous dual network. The CB[8] host-guest complexes form dynamic loops along the polymer chains between two covalent cross-linking sites. Uniaxial stretching studies were conducted to further investigate the nonlinear and viscoelastic behavior of the dual networks. The notch-insensitiveness is evidenced when a notched sample was stretched, the notch was dramatically blunted and remained stable during stretching until a critical strain of 7x. These aqueous dual networks are stretchable and tough, showing efficient energy dissipation, and can be fully self-recovered upon relaxation through the reformation of host-guest complexes at room temperature. Both dynamic supramolecular interactions and chemical cross-links have been readily combined within a single system, and such dual network fabrication represents a powerful and facile strategy for the construction of biomimetic supramolecular materials, holding great promise for myriad applications, including artificial muscles, cartilage replacement and tissue engineering, wearable electronic devices, and microactuators.
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