Influence of coalescing aids on the film formation of water-borne coatings

The results revealed that coalescing aids increased the viscosity through particle swelling and solvation, with the effect being stronger with more hydrophilic solvents.

Combination shows best results

The results obtained with electrochemical impedance spectroscopy (EIS) and indentation tests showed that hydrophilic coalescing aids were more efficient because of the partitioning on the particle interfaces but they could temporarily decrease the water resistance. The ease of coalescence was countered by solvent retention, which complicated the dynamics of film formation. EIS was used to optimise a real-world coating formulation and identify the pitfalls arising from the complex dynamics of film formation. The best resistance to humidity was obtained with a combination of hydrophobic and hydrophilic coalescing aids.

The study is published in: Applied Polymer Science.