Single-walled carbon nanotubes (SWCNT) covalently modified with OH functional groups were assembled into buckypapers through solvent dispersion and vacuum filtration. These SWCNT-OH buckypapers were subsequently crosslinked by wetting with bifunctional linkers followed by hot compression, causing reaction with OH functional groups on the side-walls of the SWCNTs to form three-dimensional covalently cross-linked buckypapers with modified properties. Cross-linking also was performed using SWCNT encapsulated with a functionalized polymer wrapping in a core-shell structure, where OH or/and NH2 groups are available on the surface. Cross-linked SWCNT buckypapers retain the porous character typical of buckypaper. Several cross-linking approaches dramatically improved the mechanical properties. The strongest and stiffest papers (σ = 32 MPa, E = 3.1 GPa), which approach 10× stronger and stiffer than the pristine non-crosslinked buckypaper, were obtained at the expense of a loss of electrical conductivity. In other cases, such as cross-linking using an epoxy resin monomer, improvements in strength and stiffness of ~5× were obtained while retaining electrical and thermal conductivity. Epoxy-crosslinking also was found to be favorable for production of buckypaper-epoxy composites, where cross-linking using a multifunctional epoxy resin prior to impregnation with the same epoxy resin results in substantially better mechanical properties in comparison to epoxy-impregnation alone.
Journal: TechConnect Briefs
Volume: 1, Advanced Materials: TechConnect Briefs 2015
Published: June 14, 2015
Pages: 144 - 147
Industry sector: Advanced Materials & Manufacturing
Topic: Carbon Nano Structures & Devices