Levelling additives find widespread use in industry to improve the surface properties of coatings and paints. Without such additives, many solvent-borne coating formulations are prone to excessive defect formation, significantly degrading their functionality and visual appearance. The origin of these defects can often be traced back to the high surface tension of the applied liquid film, preventing sufficient flow and levelling. Therefore, amphiphilic block copolymer additives are added to the formulation. These additives autonomously segregate to the coating surface and reduce the surface tension of the film. Although virtually every coating and paint formulation contains these levelling additives, much is still unknown about the influence of specific block copolymer properties and the effect of the coating matrix characteristics on the interfacial affinity of these amphiphiles.

I will discuss the main findings of our work in the investigation of the surface affinity, segregation, and phase behaviour of well-defined linear diblock copolymers containing an apolar polydimethylsiloxane (PDMS) and a polar polyether block, in a solvent-borne coating formulation, in the cured films and during the drying process. Exceptionally high surface enrichment was achieved, with significant silicon concentrations being detected within the top few nanometres of the coating layer. The characteristics of the polymer blocks, e.g. their size or chemical nature, as well as the monomeric composition of the acrylic binder were all shown to affect the additive behaviour and can thus be used to precisely tune surface properties of both the liquid film and the final cured surfaces.