Mechanically Transparent Adhesives for Stretchable Materials

Joining soft, flexible materials, such as fabrics and foams, presents unique challenges due to their surface topography, porosity, and the need to maintain adhesion and mechanical properties under large deformations. Conventional methods require damaging processes, such as sewing or the use of harmful solvents to achieve sufficient penetration for mechanical interlocking. To address these challenges, we present a bioinspired solvent-free, dual-network adhesive designed for seamless integration with stretchable materials. We use an ABA triblock copolymer, poly(methyl methacrylate)-poly(<i>n</i>-butyl acrylate)-poly(methyl methacrylate) (PMMA-<i>b</i>-PnBA-<i>b</i>-PMMA), where PMMA self-assembled microdomains provide structural integrity and the PnBA matrix ensures elasticity and adaptability. A secondary poly(<i>n</i>-butyl acrylate) (PnBA) network, polymerized <i>in situ</i>, locks the structure in place and allows for tunable mechanical properties (Young's modulus: 0.17-1.18 MPa) to match different substrates. This architecture enables seam bonds that match the mechanical behavior of the adhered material across a wide range of strains, creating "mechanically transparent seams". The use of compatible reactive monomers to mobilize the multiphase copolymer permits the formation of highly integrated bonds without the use of harmful solvents, providing an eco-friendly, high-performance bonding solution for industries requiring flexible, durable, and sustainable adhesion technologies.