A team of researchers from Virginia Tech has developed extra-sticky adhesives that break down into their original components as soon as they outlive their usefulness.

The team explained that polymers are long chains of molecules that are linked in a repeating pattern. When polymers get bunched up, the team added, they end up with a range of properties.

Source: Virginia Tech

For instance, some entangled polymers can create hard plastics, while others produce materials that are rubbery, elastic, soft, conductive, resistant — and, for the purpose of this research, sticky.

While sticky polymers are the primary ingredient in assorted adhesives — think tape and sticky notes, for example — they typically need a nonrecyclable plastic backing and chemical additives to work effectively. Further, such sticky residues leave cardboard boxes and other products unrecyclable.

As such, the team developed a tape featuring adhesive and plastic backing layers that can be recycled together. Aptly called a "mono-material," both of the tape’s layers are chemically similar but perform different functions.

The researchers synthesized large, tacky polymers from lipoic acid, a naturally occurring sulfur-based compound found in foods such as broccoli and spinach. By varying the acid concentration, they optimized the balance between stickiness and cohesiveness, resulting in an adhesive that delivers greater adhesion strength than heavy-duty duct tape while remaining chemically recyclable.

Meanwhile, a second, mild chemical reaction breaks down the adhesive and backing layers into their original components, which can then be rebuilt into new adhesive tapes.

In another Virginia Tech lab, a stronger degradable adhesive was also developed, with the team using a different polymer, dubbed bottlebrush polymers, which feature a central backbone and side chains that protrude like bristles.

The team strung together molecules of a viscous oil and a gas to develop a new, transparent variation of the bottlebrush polymer, which was then turned into tape.

When trialed in the lab, the material proved four times stronger than the adhesives used in duct tape. Importantly, the adhesive degrades in a matter of minutes when saturated with mildly alkaline water.

An article detailing the work, “Mono‐Material Polydisulfides for Pressure Sensitive Adhesive Tapes With Closed‐Loop Recyclability,” appears in the journal Advanced Functional Materials.

The second study, "Bottlebrush Polyolefin Sulfones as Triggerable and Degradable Pressure‐Sensitive Adhesives," appears in the journal Angewandte Chemie International Edition.

For more on the adhesives, watch the accompanying video that appears courtesy of Virginia Tech.