Tensile benefits of nanofibers in commercial paint films

Abstract

Polymerization-induced self-assembly (PISA) in dispersed phase polymerization enables the synthesis of fibers and other self-assembled nanostructures at the quantities and cost required for use in commodity paints. Here we studied the effect of adding three types of fibers to coatings of two commodity paints with different glass transition temperatures (T_g). Film-forming (FF) fibers and rigid polystyrene (PS) fibers analysed were synthesized by RAFT-PISA at ∼20 g scales with a promising degree of purity (75% and 63% respectively), with kilogram-scale synthesis also demonstrated. These fibers, as well as naturally sourced microfibrillated cellulose fibers, were added to paint, and their effect was tested on the stain resistance and tensile properties of the coatings produced. The fiber content added was determined by the desired viscosity needed for the application of coatings. The extensibility of both paint coatings was shown to decrease with the addition of the high T_g PS fibers, whereas extensibility and toughness increased with the addition of low T_g FF fibers. Cellulose fibers were seen to increase extensibility at low loadings, but in turn added hydrophilic and hygroscopic components, exposing the paint to increased staining. In contrast, the FF fibers showed a notable improvement in stain resistance in addition to the tensile benefits conferred. No significant change in strength was observed for any combination of paint and nanofibers.