Soft core–hard shell latex particles for mechanically strong VOC‐free polymer films

ABSTRACT Polymer films cast from aqueous polymer dispersions typically suffer from an inherent lack of mechanical strength when compared to their solvent‐borne counterparts. This drawback can be overcome by the use nanostructured hybrid particles that contain both a hard and soft phase. In this work, we demonstrate the use latex particles consisting of a soft core with a multilobed hard shell synthesized by seeded semicontinuous emulsion polymerization with the aim of maximizing the interconnectivity of the hard phase in the resulting polymer film, thus generating films with improved mechanical properties. Films with a minimum film formation temperature (MFFT) close to that of the soft phase are formed while obtaining a Young's modulus up to 4.5 times higher that of a standard homogeneous latex particle. The effect of annealing temperature on film morphology is also investigated, clearly demonstrating that a marked difference in mechanical properties is observed when a percolating network of the hard phase within the film is obtained. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47608.