Adhesive Interfaces toward a Zero-Waste Industry

Abstract

This Feature Article evaluates ongoing efforts to adapt adhesives toward the goal of zero-waste living and suggests the most promising future directions. Adhesives are not always considered in zero-waste manufacturing because they represent only a small fraction of a product and offer no additional functionality. However, their presence restricts the reintegration of constituent parts into a circular economy, so a new generation of adhesives is required. Furthermore, their production often leads to harmful pollutants. Here, two main approaches toward addressing these problems are considered: first, the use of natural materials that replace petroleum-based polymers from which conventional adhesives are made and second, the production of dismantlable adhesives capable of debonding on demand with the application of an external stimulus. These approaches, either individually or combined, offer a new paradigm in zero-waste industrial production and consumer applications.

Chemical and Physical Debonding-on-Demand of Poly(urethane urea) Thermoset Adhesives to Facilitate the Recycling of Engineered Wooden Products

“…With discussions of circularity and sustainability in the building and construction sector becoming more prevalent, the technology associated with on-demand material debonding has become a hot topic, evidenced by the reviews and perspectives published in the last 3 years alone. − Debonding of two adherends occurs when the adhesive fails either in the glue line or in the adherend, cohesive failure, or at the glue–adherend interface, adhesive failure. Depending on their desired application, adhesives can consist of thermoplastic or thermoset polymers.…”

“…In the field of adhesive debonding, there are three main techniques to consider, namely, reactive fillers, electrically debondable adhesives, and reworkable adhesive systems. , Reactive fillers have been utilized to debond automotive thermoset adhesives, including a two-component epoxy adhesive and a two-component structural polyurethane adhesive, − and are commercially available as thermally expandable particles (TEPs). TEPs are micron- or nano-sized and conventionally made of a thermoplastic polymer shell filled with a thermally unstable molecule or volatile alkane.…”

Acrylonitrile‐butadiene‐lignin thermoplastic rubber adhesive for enhanced metal‐to‐metal joining

“…4 Several guiding principles have been posted to direct adhesive manufacturing in a more sustainable manner: replacement of petroleum-based components with bio-based alternatives, solvent-free formulations, and replacement of organic solvents. 5 Developing more sustainable adhesives is a partial way to address all the environmentally related issues. The main challenges to realizing the circular economy and reducing waste production in the adhesive industry are to modify the current status in the areas of the sustainability of raw materials and adhesive products, recovery, and recycling after use, and feasibility of reintroducing components into the production flow.…”

“…The main challenges to realizing the circular economy and reducing waste production in the adhesive industry are to modify the current status in the areas of the sustainability of raw materials and adhesive products, recovery, and recycling after use, and feasibility of reintroducing components into the production flow. 5 To that end, our ongoing work on lignin-based thermoplastics, 6,7 if useful as adhesive, has the potential to improve its sustainability and because of its thermoplastic nature, the bonded joint can be disassembled by heating above the adhesive's glass transition temperature. As the main component of a potential formulation, lignin exists as the second most abundant biopolymer on earth.…”

A reversible water‐based electrostatic adhesive

“…The development of reversible adhesives, which are triggered by a change in temperature, [1] hydration, [2] an electrical potential, [3] exposure to radiation, [4] a magnetic field, [5] or a change in pH, [6] are of interest from both scientific and industrial perspectives. [ 7 , 8 , 9 ] The mechanism of debonding for each case depends on the interfacial chemistry between two surfaces, which very often precludes their integration into large scale industrial processes.…”