A nano-TiO2/regenerated cellulose biohybrid enables simultaneously improved strength and toughness of solid epoxy resins

The intrinsic brittleness has significantly restricted practical applications of epoxy resins. Existing toughening strategies often lead to degraded mechanical strength. Hence, it has been attractive but a huge challenge to design high-performance sustainable additives that can simultaneously improve strength and toughness of epoxy resins. Here, we report the synthesis of a nano-TiO2/regenerate cellulose (RC) biohybrid via a facile microwave method for strengthening and toughening a soft epoxy resin system (modulus below 1 GPa). Our results show that with 10 phr nano-TiO2/RC, the resultant epoxy composite exhibits simultaneous enhancements in tensile strength and impact toughness, ca. 38% and 40% higher than corresponding values of virgin epoxy resin because of improved interfacial compatibility. Moreover, the addition of as-designed nano-TiO2/RC can enhance thermostability of epoxy resin. It has a slightly negative effect on the curing reaction but does not change the curing mechanism of epoxy resins. This study provides a facile, efficient and green method for preparing bifunctional additive for creating strong and tough epoxy composites, which are expected to find wider applications in industries.