Graphene Oxide With an Interfacial Buffer Layer for Epoxy Resin Modification
Shulei Ren, Xiaoyan Liu, Wanjun Zhang, Chenyao Cai, Dan Li, Junhui Dong, Haiping Qi, Wen Ma, Jun LiuABSTRACT
Graphene oxide (GO) can simultaneously strengthen and toughen epoxy resin (EP), but sheet restacking and limited interfacial compatibility restrict its effectiveness. In this study, a flexible‐chain hyperbranched epoxy resin (F‐HBEP) was synthesized via a one‐step A 2 + B 3 reaction in the presence of GO to obtain F‐HBEP‐modified GO (FGO). GO was added before polymerization and remained in the reaction medium throughout synthesis. Flexible aliphatic segments derived from 1,4‐butanediol were incorporated into the hyperbranched structure to provide an interfacial buffer layer. Spectroscopic, structural, and thermal analyses supported GO surface modification with F‐HBEP and indicated increased interlayer spacing and suppressed ordered restacking. At an FGO loading of 0.5 wt.%, the tensile strength, flexural strength, and impact toughness of the composite increased by 58.1%, 50.9%, and 192.1%, respectively, relative to neat EP. The composites also exhibited a higher glassy storage modulus, a broader loss response, while maintaining initial thermal stability. Fractographic observations indicated improved interfacial contact, rougher fracture surfaces, and more tortuous crack paths. These improvements were attributed to load transfer and crack deflection by GO, combined with stress buffering and energy dissipation by the flexible F‐HBEP interfacial layer. This work provides a feasible polymerization‐stage route for tailoring the overall mechanical performance and maintaining the initial thermal stability of epoxy nanocomposites.