Internally reinforced soft core-hard shell waterborne dispersions for high performance crack and solvent free coatings

Waterborne polymer dispersions composed of soft core-hard shell particles allows obtaining mechanically robust coatings that can be cast at low temperatures without the use of coalescent agents. However, the presence of a hard phase at the outer shell of the particle increases the stress generated during film formation leading to cracks. The need of forming films free of cracks limits the mechanical properties of the coating. This article explores a strategy of enhancing the mechanical properties of waterborne coatings without compromising the film formation properties of soft core-hard "shell" polymer particles. The approach is based on a multiphase internal core composed by hard and soft domains. This strategy resulted in coatings with higher Young's modulus, stress at break and toughness, without compromising the film formation characteristics.