Tuning the mechanical properties of epoxy-acrylate core–shell nanostructured film via epoxy concentration in the core layer

Abstract

Epoxy-acrylate (EA) core–shell nanoparticles have gained significant attention recently due to their dual unique properties as heterogeneous materials, particularly in coating applications. However, the effect of epoxy (EP) concentration in core layer on mechanical properties is still limited, and the mechanism of how it affects the film's performance is not well understood. In this study, we investigate the effect of varying EP concentration in the core layer on the mechanical properties of nanostructured films containing EA core–shell nanoparticles. The core–shell nanoparticles were synthesized through multistage seeded emulsion polymerization. The transmission electron microscopy (TEM) images revealed similar particle morphology and size in all EA nanoparticles. Differential scanning calorimetry (DSC) analysis confirmed the successful synthesis of core–shell particle morphology with two glass transition temperature (T_g) values (~12 °C and ~ 60 °C) observed for the core and shell layers, respectively. We observed an increase in the T_g values of the shell layer with higher EP content in the core layer. The use of EP-based copolymers raised the T_g values of the shell layer, significantly affecting the film formation behavior and their mechanical properties through interlayer crosslinking. Tensile modulus values for the films ranged from 200 to 500 MPa, marking the highest modulus reported for cast films of EA nanostructured films. Our findings reveal a straightforward and versatile method for producing high-modulus EA nanostructured films with customizable mechanical properties, making the model ideal for enhancing wood coating performance.