Epoxy Composite Fibers Reinforced with Aligned Single-Walled Carbon Nanotubes Functionalized with Generation 0-2 Dendritic Poly(amidoamine)

Single-walled carbon nanotubes functionalized with generation (n) 0-2 dendritic poly(amidoamine) (denoted as SWNTs-G(n)-NH2, n = 0, 1, or 2) were used as filler in thermosetting epoxy to prepare anisotropic microscale diameter fibers by reactive spinning. Dendritic poly(amidoamine) (PAMAM) was "grafted from" acid-modified and toluene 2,4-diisocyanate-activated SWNTs by repeating amidation of terminal ester groups via ethylenediamine (EDA) and Michael addition of methyl acrylate (MA) to amino groups. Fourier transform infrared (FTIR) and hydrogen nuclear magnetic resonance (H-1 NMR) spectroscopy and thermogravimetric analysis (TGA) confirmed the successful grafting and generation buildup. Optical and scanning electron microscope (SEM) observations revealed that PAMAM-functionalized. SWNTs dispersed in epoxy much more uniformly than pristine nanotubes. The dispersibility improved with increasing generation number. Microsized fibers made of epoxy reinforced with aligned SWNTs-G(2)-NH2 by reactive spinning show high tensile strength and Young's modulus per unit weight fraction (d sigma/dW(NT) and dE/dW(NT)). The respective measures are 7022 MPa and 118.0 GPa, which is a high reinforcement efficacy in comparison to other fillers. The nanotube alignment and grafting of dendritic PAMAM play a crucial role in the enhancement of the tensile strength of these reinforced composite fibers.