Construction of Poly(butylene succinate)-Grafted Graphene Bionanocomposites: Intercalation Structure, Synergistic Thermal–Oxidative Stabilization Effect, and Hydrolytic Behavior

Poly­(butylene succinate) (PBS) is considered a promising biodegradable material, whereas poor mechanical/thermal properties and low hydrolysis rate restrict its further application. Herein, 1,4-butanediol (BDO) was chemically grafted onto the graphene oxide (GO) surface by the coupling effect of diisocyanate [e.g., 4,4′-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI)], and the corresponding bionanocomposites were prepared via in situ polymerization. By comparison, MDI has higher reactivity with GO and BDO due to induction and the spatial steric effect, and a strong interfacial covalent interaction of GO–MDI–PBS was formed. Therefore, more PBS molecules were grafted onto GO and intercalated into nanosheet layers to achieve a uniform dispersion in the matrix. GO–MDI–PBS-0.5 wt % exhibited the maximum tensile strength (39.96 MPa), elongation at break (458.48%), and notched impact strength (9.80 kJ/m2), nearly 21.27, 44.58, and 127.91% increase than those of neat PBS, respectively, achieving simultaneous improvement in mechanical strength and toughness. Besides, effective intercalation enlarged the contact area with free radicals, resulting in extraordinary radical scavenging ability of GO, and the excellent oxygen barrier property of the composite was enhanced because the uniform dispersion of GO sheets caused a more tortuous diffusion pathway for oxygen, which endowed GO–MDI–PBS with remarkable thermal–oxidative stability. Furthermore, GO–MDI–PBS exhibited the improvement of crystallization rate, surface hydrophilicity, and water vapor barrier properties, effectively promoting hydrolysis.