Deformation and adhesion of a periodic soft-soft nanocomposite designed with structured polymer colloid particles

Although poor mechanical properties are usually found in films cast from waterborne colloidal polymers relative to their solvent cast counterparts, these materials offer the opportunity to control structure and composition very precisely at the nanoscale. Here, we introduce a knowledge-based strategy to design what we call a "soft-soft nanocomposite" in which a percolating crosslinked phase contains a second less crosslinked dispersed phase distributed regularly throughout it. This new type of structure uses polymer colloid particles as building blocks in a bottom-up approach to obtain simultaneously a very viscoelastic behaviour at small strains and an elastic behaviour at larger strains, bringing highly desirable properties for adhesives applications. For instance, the adhesion energy of the soft-soft nanocomposite on polyethylene is more than four times greater than that of a commercial material in which the particles are crosslinked and the interfaces are entangled. Our conclusions are broadly applicable to a large class of soft materials based on deformable polymeric networks, such as gels, elastomers and artificial tissues.