Strategies towards improved performance of waterborne coatings through multiplying the ionic interparticle interactions

In this work, a new route to increase the sustainability of acrylic polymer films by enhancing not only the mechanical properties of the films but also their water resistance is presented. For that, butyl acrylate (BA) and methyl methacrylate (MMA) are used as main monomers in 50/50 wt ratio to provide film forming ability to the waterborne dispersions. Three different functional monomers are incorporated, sodium styrene sulfonate (NaSS), 2-dimethylamino (ethyl methacrylate) (DMAEMA) and 1,4-diazabicyclo[2.2.2] octane (DABCO) to provide ionic character to the polymer dispersions. Polymer particles of opposite charges and different sizes are blended, and the surface characteristics as well as the mechanical properties and water resistance are measured. It is shown that an efficient particle packing is a key to increase the ionic bonding points and reinforce the film in terms of tensile and water uptake behavior. On the other hand, it is also demonstrated that the surface charge density plays an important role in establishing dense ionic complexes. Consequently, reinforced films that are moreover completely impermeable to water are prepared, making this strategy closer to practical application.