Antioxidant modified graphene oxide for robust and highly aging resistant rubber composites

In this work, rubber antioxidant poly(1,2-dihydro-2,2,4-trimethylquinoline) (RD) was introduced as organic surface modifier of graphene oxide (GO) for the preparation of robust and highly anti-aging rubber composites. It was found that RD was chemically grafted on GO surface by C–N bond. Interestingly, the oxygen-containing groups on GO were also substantially removed after surface modification, indicating the good reducing capability of RD on GO. As RD with large molecular weight could significantly diminish the restacking of graphene sheets and form inherent π–π interaction with styrene moieties in styrene-butadiene rubber (SBR), the modified GO (G-RD) showed fine dispersion in SBR matrix and improved interfacial interaction with rubber chains, leading to much better mechanical performance and thermal conductivity of SBR/G-RD composites than those of SBR composites with hydrazine hydrate reduced GO (H-G). Moreover, thanks to the improved barrier effect of G-RD due to its good dispersion and suppressed physical loss of RD due to its chemical grafting, SBR/G-RD composites exhibited exceptionally high long-term thermal-oxidative aging resistance compared with SBR composites with H-G and ungrafted RD, indicating that G-RD can well fit the bill of long-term applications of unsaturated rubbers in some harsh service conditions.