A reversible water-based electrostatic adhesive

Commercial adhesives typically fall into two categories: structural or pressure sensitive. Structural glues rely on covalent bonds formed during curing and provide high tensile strength whilst pressure-sensitive adhesives use physical bonding to provide weaker adhesion, but with considerable convenience for the user. Here, a new class of adhesive is presented that is also reversible, with a bond strength intermediate between those of pressure-sensitive and structural adhesives. Complementary water-based formulations incorporating oppositely charged polyelectrolytes form electrostatic bonds that may be reversed through immersion in a low or high pH aqueous environment. This electrostatic adhesive has the advantageous property that it exhibits good adhesion to low-energy surfaces such as polypropylene. Furthermore, it is produced by the emulsion copolymerization of commodity materials, styrene and butyl acrylate, which makes it inexpensive and opens the possibility of industrial production. Bio-based materials have been also integrated into the formulations to further increase sustainability. Moreover, unlike other water-based glues, adhesion does not significantly degrade in humid environments. Because such electrostatic adhesives do not require mechanical detachment, they are appropriate for the large-scale recycling of, e.g., bottle labels or food packaging. The adhesive is also suitable for dismantling components in areas as varied as automotive parts and electronics. A reversible water-based electrostatic adhesive has been developed through conventional emulsion polymerization using commodity materials. It is made of two formulations, one containing a polycation, and other a polyanion. Detachment is only promoted in highly acidic or alkaline solutions as polyelectrolytes show distinctive charged states. This kind of adhesive would be useful for the recycling and dismantling of products.image

Automated summary

A reversible water-based electrostatic adhesive has been developed, with intermediate bond strength between pressure-sensitive and structural adhesives, suitable for large-scale recycling and dismantling.