Revolutionary Reusable Adhesives: A New Era for Composites

For decades, composite adhesives like epoxy resins have been crucial in various industries due to their strength and durability. However, their permanent nature poses challenges for repair, recycling, and reprocessing. Researchers at UC Berkeley have introduced a new class of composite materials that are equally robust but can be disassembled and reused. This innovation tackles the limitations of traditional adhesives by using physical entanglements between long polymer chains, termed "pseudo-bonds," instead of irreversible chemical bonds. Lead author Ting Xu explains that this approach opens a new path to composites, drawing inspiration from nature and biology. The team engineered a nanocomposite using polystyrene and silica nanoparticles, creating "hairy particles" where polymer chains interweave and pack together, forming a crystal-like structure. The nanoconfinement of these polymer chains allows for precise control over entanglement and material properties. Microscopic images confirmed the pseudo-bond mechanism, showing polymer chains extending and disentangling under stress. This technology can be adapted to various polymer and filler particle combinations, enabling the design of composites with tailored functionalities. Potential applications include flexible electronics, advanced sensors, optoelectronic devices, and industries reliant on non-recyclable composites, paving the way for a more sustainable future.