Tough films with ultralow content of hard phase

Latexes are colloidal dispersions of polymer particles in water. They are now used in a broad range of applications and represent an attractive alternative to solvent-based formulations because of decreased organic compound emission. In particular, all-acrylic latexes possess great potential…

Latexes are colloidal dispersions of polymer particles in water. They are now used in a broad range of applications and represent an attractive alternative to solvent-based formulations because of decreased organic compound emission. In particular, all-acrylic latexes possess great potential for applications as adhesives or coatings. However, they generally lack mechanical stability and resistance to solvent or water.

Laurent Bouteiller and co-workers (Paris) could now prepare block copolymer films with a remarkable increase in both stiffness and toughness. Using RAFT emulsion polymerization they were able to synthesize very asymmetric poly(acrylic acid)-b-poly(n-butyl acrylate) (PAA-b-PBA) diblock copolymers that self-assemble during polymerization into core-shell particles composed of a soft PBA core and an ultrathin PAA shell. The derived films possess a thin percolating honeycomb nanostructure with both a sharp and a strong interface between the hard and soft phases resulting in improved toughness and resistance to water and organic solvents.

This methodology provides a general strategy to design nanostructured polymers with a low volume fraction percolating phase which can be highly interesting for applications where ionic or electronic conductivity is important.