Core–Shell Starch Nanoparticles and Their Toughening of Polylactide

While polylactide (PLA) is considered to be a promising renewable materials, broader application is hindered by its brittle nature and high cost. PLA-based nanocomposites with enhanced toughness were fabricated by blending of commercial PLA and core–shell starch-based nanoparticles (CSS NPs), in which the CSS NPs were synthesized via gelatinization of the esterified starch to form a hard core, followed by soap-free emulsion copolymerization of ethyl acrylate to form poly(ethyl acrylate) (PEA) as the outer shell. A synergistic association of hard starch and the soft PEA induced unique toughening effects on the PLA. In particular, with addition of 20 wt % CSS NPs, the elongation at break and notched impact strength of PLA/CSS nanocomposite reached to 412% and 31.4 kJ·m–2, which are simultaneously 61 and 9 times higher than that of pure PLA, respectively. More important, the resulting nanocomposites still retained relatively high tensile strength similar to pure PLA. These results establish a strategy for PLA composites applications.