Starch/polylactide sustainable composites: Interface tailoring with graphene oxide

The high production cost of polylactide (PLA) can be effectively reduced by simply mixing with starch, unfortunately a trade-off of its mechanical properties. In this paper, we reported a new strategy in which graphene oxide (GO) was used as a compatibilizer to bridge PLA and starch. The native starch was first cationized and then encapsulated with GO by electrostatic force between the negatively charged GO and the positively charged cationic starch. The encapsulating GO was reduced by the quaternary ammonium ions on the cationic starch, which converted the surface of the starch from hydrophilic to hydrophobic. Due to the amphipathicity approximation between PLA and starch, a good dispersion as well as a strong interfacial adhesion was achieved. The PLA composite reinforced with GO encapsulated starch exhibited much higher yield strength than that of pure PLA, increasing from 36.64 MPa up to 41.40 MPa.