Water-based adhesive for zero-waste economy

The purpose of this proposal is to create a water-based reversible adhesive using commodity materials that is inexpensive, scalable, and environmentally friendly. The target impact of this research is a commercially successful adhesive that has widespread applications, particularly in areas where recycling is important, such as bottle labelling. Other areas, such as automotive parts and e-waste management, would also benefit by supporting a design for an environment approach in which, at the end of the first life cycle, products can be dismantled, and parts repurposed. The technology can also function as a simple water-based adhesive to replace other glues based on volatile organic compounds. The premise is simple: a surface coated with a positively charged polymer can adhere to one coated with a negatively charged polymer. These will stick in water and remain adhered even after the contact has dried. Changing the local pH changes the charge on the polyelectrolytes so that, in an acid pH, the polyacid will become neutral. The polybase will remain charged and the adhesion fails. Previous demonstrations of reversible adhesion have required the end-user to perform significant chemistry. Here we are proposing a simple route to reversible adhesion based on a standard polymerization process. The surfaces to be adhered would each be coated by separate layers and joined. Adhesion is expected to be instantaneous and durable. Unlike other water-based adhesives, exposure to moisture would not compromise the joint. An acid or alkaline wash would be used to separate the two components. A rapid and effective means of disjoining requires significant research and forms a large part of this proposal. In addition, the spray coating of polyelectrolytes onto surfaces will also be explored as a simple route to adhesion for a limited range of applications. The technology will be validated in collaboration with partner companies.