Preparation of SiO2@EVA core–shell particles via post-emulsification method with polydisperse SiO2 particle sizes and the critical thickness-to-diameter ratio in PA6/SiO2@EVA system

•Synthesis of SiO2@EVA core–shell particles with polydisperse particle sizes by post-emulsification method.•The ratio of the rubber shell thickness to the SiO2 core diameter (τ) is determined by the weight ratio of them.•The value of τ has nothing to do with the SiO2 particle size.•The critical value of τ that brittle-ductile transition happens in PA6/SiO2@EVA core–shell toughening system with polydisperse particle sizes is 0.069.