Rational, knowledge-based design of adhesives Scientists are studying a special class of adhesives and developing models facilitating their better design. The simulations may well lead towards rational design of high-performance and eco-friendly products. Industrial Technologies © Thinkstock In composite materials made of more than one individual component, stresses and interactions at interfaces play an important role in resulting stability, durability and deformation. Scientists initiated the EU-funded project 'Multi-scale modelling of interfacial phenomena in acrylic adhesives undergoing deformation' (Modify) to enhance understanding of such phenomena in soft nano-structured adhesives. In particular, scientists focused on interactions between the soft latex particles in acrylic pressure-sensitive adhesives (PSAs) as well as the interface between adhesive and substrate. Many important applications involve contact between a soft polymer and a hard substrate. Thus, models of both types will be relevant screening tools for a variety of products. Modify developed sophisticated multi-scale models of stress transfer at internal surfaces between latex particles with polymers of varying topologies. In addition, scientists investigated stress transfer at hard–soft interfaces between substrate and soft adhesive as a function of chemical composition of both. Scientists incorporated microscopic physicochemical interactions at interfaces as related to materials compositions. Studies at the molecular level were complemented by meso- and macro-scale investigations to appropriately describe adhesive behaviour. Given that deformations in soft adhesives cause breakage of internal cavities leading to formation of thin and highly elastic filaments, researchers investigated how these are related to the initial formulation of the adhesive. They also incorporated polymer viscosity and fluid flow (rheology) into the multi-scale models. Although the work was quite challenging, it was necessary to enable knowledge-based rational design of acrylic PSAs for specific performance characteristics. The European PSA market is quite large and even more so when products made with PSA are considered. Increasing energy costs and regulatory pressures impose a need for energy-efficient and environmentally friendly production processes and materials with good recyclability. Successful modelling of the adhesion process and failure mechanisms will have direct impact on design of PSAs that meet all performance and environmental specifications, and thus on the competitive position of the EU in a large global market.
