Effect of polyaspartic acid‐functionalized graphene oxide on the mechanical performance of polyimide‐based composites

ABSTRACT Graphene oxide (GO) can improve the mechanical property of polymer matrix greatly. However, its poor dispersibility may considerably lower reinforcing efficiency. To address this problem, the environment‐friendly polyaspartic acid (PASP) was adopted to modify GO through two generally modified methods: hydrogen bond adsorption and chemical graft modification. Findings indicate that the covalent bond grafted PASP–GO exhibits better dispersibility than the product by noncovalent method (PASP/GO‐noncovalent). For chemically grafted PASP–GO, the nearly spherical polymer nanoparticles are formed on the GO nanosheets through self‐polymerization, and its size can be well manipulated by adjusting the dosage of PASP so as to yield PASP–GO‐1/4, PASP–GO‐1/2, and PASP–GO‐1/1 (mass ratio: m PASP / m GO = 1/4, 1/2, and 1/1); the corresponding diameters of these polymer aggregates are 56.4 ± 7.1, 90.1 ± 12.6, and 151.2 ± 16.1 nm. They are further utilized to reinforce polyimide matrix. Compared with the PASP–GO‐1/2 and PASP–GO‐1/1, the smaller PASP–GO‐1/4 has better strengthening effect, due to its high specific surface area and dense distribution. This desirable fabrication of GO‐based nanofillers provides a new avenue on the development of polymer matrix with comprehensive performances. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47939.