Particle size and shell composition as effective parameters on MFFT for acrylic core-shell particles prepared via seeded emulsion polymerization

In this study, acrylic-based copolymer particles were prepared with core-shell morphology and the effect of Tg of the shell, particle size and their bimodal size distribution on minimum film formation temperature (MFFT) were investigated. The main goal was to optimize conditions to obtain latexes with low MFFT and appropriate mechanical properties. These will develop the applicability of such water-borne binders as paints and coatings at ambient conditions. A series of latexes with core-shell morphology with variable Tg of the shell from −56 to 30 °C were prepared and the MFFT, hardness and thermal behavior of the obtained films were studied. Then a series of latexes with particle sizes ranging from 46 to 960 nm were prepared and the effect of particle size on MFFT was studied too. By inducing the formation of secondary nucleation during emulsion polymerization, latexes with bimodal size distribution were obtained and the effect of presence of such particles on film formation was investigated. Results indicate that latexes with appropriate composition and bimodal particle size distribution lead to optimized performance in both mechanical and film formation properties as a proper choice for water-borne coatings.