The adhesives used to stick labels onto plastic bottles and packaging often leave behind a detrimental residue that limits how the plastic can be recycled and reused.
A research team from the Department of Chemistry at the University of Reading has created a new polymer adhesive that breaks down when treated with basic or alkaline solutions. This means labels can stay firmly stuck to bottles during normal use but can be easily removed as part of the recycling process.
Matthew Hyder, lead author of the research, said: “Existing commercial adhesives can prove extremely difficult to remove from plastic surfaces because of their chemical composition. Our new polymer adhesive has been designed so that it can be removed from a plastic surface when exposed to basic or alkaline solutions. By making labels that can be removed completely, we are helping improve the quality of recycled plastic and usefulness in its next life."
Multiple uses
Published last month in the journal Macromolecules, the study describes how researchers designed and generated a polyurethane that incorporated sulfonyl ethyl urethane units, which act as a chemical switch when exposed to certain substances. In tests, treating the polymer adhesive with basic or alkaline solutions triggered this switch, making it lose up to 65% of its sticking power on a range of surfaces.
