Designing Rebondable Structural Adhesives

Reversible adhesion inspired by the gecko has attracted attention in applications such as biomedical masks, climbing robots, transfer printing, and pressure-sensitive adhesives. The approaches used to accomplish reversible adhesion are typically classed into two categories: patterned and non-patterned. The first category uses a micro-patterned surface that mimics well-known biostructures, while the latter category does not. Reworkable adhesives include thermoplastics that melt at an elevated temperature and solidify on cooling. Rework is accomplished in the melt state and allows debond and rebond/repositioning of components. One approach to the design of rebondable thermoset adhesives is through optimizing the chemical structure. This design requires the crosslinked thermoset structure to possess bonds that are labile (e.g., the bond connectivity is exchangeable between segments). Academically, these kinds of bond exchange reactions have been shown to occur even within fully thermoset networks. With this in mind, a solid-state adhesive approach based on covalent bond exchange within a high-temperature polymer presents itself as an attractive solution.