Reinforcing Epoxy Polymer Composites Through Covalent Integration of Functionalized Nanotubes

• Published in: Advanced functional materials 2004-07, Vol.14 (7), p.643-648
• Main Authors: Zhu, J., Peng, H., Rodriguez-Macias, F., Margrave, J. L., Khabashesku, V. N., Imam, A. M., Lozano, K., Barrera, E. V.
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; Carbon nanotubes, functionalization; Carbon nanotubes, single‐walled; Composites; Composites, polymer–nanotube; Epoxy resins; functionalization; Polymer composites; polymer-nanotube; single-walled
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200305162

Strong interfacial bonding and homogenous dispersion have been found to be necessary conditions to take full advantage of the extraordinary properties of nanotubes for reinforcement of composites. We have developed a fully integrated nanotube composite material through the use of functionalized single‐walled carbon nanotubes (SWNTs). The functionalization was performed via the reaction of terminal diamines with alkylcarboxyl groups attached to the SWNTs in the course of a dicarboxylic acid acyl peroxide treatment. Nanotube‐reinforced epoxy polymer composites were prepared by dissolving the functionalized SWNTs in organic solvent followed by mixing with epoxy resin and curing agent. In this hybrid material system, nanotubes are covalently integrated into the epoxy matrix and become part of the crosslinked structure rather than just a separate component. Results demonstrated dramatic enhancement in the mechanical properties of an epoxy polymer material, for example, 30–70 % increase in ultimate strength and modulus with the addition of only small quantities (1–4 wt.‐%) of functionalized SWNTs. The nanotube‐reinforced epoxy composites also exhibited an increased strain to failure, which suggests higher toughness. A fully integrated nanotube–polymer composite has been developed using amino‐functionalized single‐walled carbon nanotubes (see Figure). The nanotubes become an integral part of the crosslinked epoxy structure through covalent bonding. Significant reinforcement of epoxy was demonstrated—up to 70 % increase in mechanical strength with the addition of only a small amount of functionalized nanotubes.