A comprehensive study on step-wise surface modification of C60: Effect of oxidation and silanization on dynamic mechanical and thermal stability of epoxy nanocomposite

• Stepwise modification was done to prepare silanized C60 (S-Fs).
• Silanization of C60 is demonstrated from a comprehensive physical characterization.
• Epoxy nanocomposites with blends of step-wise modified C60 were prepared.
• S-Fs confirms its potentiality to enhance stiffness and molecular relaxation of epoxy.
• Storage modulus was improved by ∼491% for S-FEC without affecting their thermal stability.

Fullerenes (C60) are regarded as exceptional reinforcing material in composites for their capability to enrich multi-functional properties. In the present work, pristine C60 has been stepwise modified through oxidation in the presence of nitric acid and then silanized using 3-aminopropyltriethoxysilane (APTES) to generate oxygenated and siloxane functional group elements onto their surfaces. The morphological investigation of oxidized and silanized C60 was done under FESEM and TEM. On the other hand, FTIR spectroscopy and TGA analysis confirms the attachment of oxygenated and siloxane functional groups. The increase in structural defect, creating sites for APTES grafting is evident from Raman spectroscopy. Epoxy nanocomposites were prepared by incorporating 0.5 wt% of pristine and stepwise modified C60. The effect of surface modification of C60 on epoxy nanocomposite is studied under DMA and TGA. The silanized C60/epoxy nanocomposite showed significant enhancement of storage modulus (∼491%) and enhanced intensity of tan δ peak compared to the neat epoxy. This is mainly attributed to high energy absorption during viscoelastic motion. From the TGA, silanized C60/epoxy nanocomposite showed modest increment in initial decomposition temperature. This behavior is suggestive for potential espousal of silanized C60 to enhance the stiffness and molecular relaxation of epoxy nanocomposites.