Waterborne acrylic-styrene/PDMS coatings formulated by different particle sizes of PDMS emulsions for outdoor applications

Abstract

This research focuses on the characteristics of water-based pigmented coatings prepared by PDMS latexes in different sizes blended with acrylic-styrene (ASC) latexes. PDMS latexes were synthesized through macro-emulsion and micro-emulsion polymerization of octamethylcyclotetrasiloxane in two different average particle sizes (i.e., 88 nm and 19 nm named mac.PDMS and mic.PDMS, respectively) and then individually blended by ASC latex in an optimum weight ratio. Compatibility and viscoelastic properties of the blends were evaluated through dynamic mechanical thermal analysis (DMTA). A single DMTA peak confirmed the compatibility between the ASC and PDMS polymers. The performance of the blends in pigmented coatings was first evaluated through measuring loading disperseability index (LDI) of the latex blends, then via measuring wet scrub resistance, dirt pick-up resistance, weathering resistance and washability in the pigmented coatings prepared from the latex blends. The LDI values of 9.5 and 10.8 were obtained for mac.PDMSand mic.PDMS/ASC blends, respectively. Test results on pigmented coatings showed both mac.PDMS and mic.PDMS led to improve outdoor performance of water-based acrylic coatings. However, mic.PDMS latex improves further weather and dirt pick-up resistances (using CIE color measurements) and washability in the coatings. Consequently, smaller particle sizes of PDMS latexes lead to enhance the performance of outdoor acrylic coatings as the waterborne and environmentally friendly materials.