*3.3. Epoxy Composites*

We employed commercially available SpeciFix-20 (Struers, Ballerup, Denmark) as the epoxy resin, which consists of a resin and a hardening agent (26:5 ratio). Unlike some epoxies that require heating or pressure, this epoxy is designed to cure under atmospheric conditions. Further, it has a working period of 60 min, allowing time for the sample to be handled and nanocomposite added and mixed prior to the onset of curing. A loading of 1% nanoparticles to 99% epoxy by weight was selected for testing. The composition of the filler materials, the hybrids and individual phases described in previous sections, is included in Table 1 below. The filler components were added to the uncured resin using sonication and the composite was left for a period of at least 24 hours to cure into a hard puck. After the nanoparticles were successfully embedded into the epoxy matrix, the surface of the pucks was mechanically polished to remove scratches and imperfections and then transferred to the nanoindentor.


**Table 1.** Filler compositions used for epoxy composites (first column).
