Dispersion of Multi-Walled Carbon Nanotubes Modified with Poly-L-Lysine in Water

A noncovalent method was presented in order to improve the solubility of multi-walled carbon nanotubes (MWCNTs) in water. Poly (ε-benzyloxycarbonyl-L-lysine) (PZLL) was prepared by ring-opening polymerization of ε-carbobenzoxy-L-lysine N-carboxyanhydride (Z-L-Lys NCA). After the removal of the benzyloxycarbonyl group, water-soluble poly-L-lysine (PLL) was obtained. The structure of PZLL and PLL was characterized by FTIR and 1H NMR. Dispersion of MWCNTs in the water solution of PLL was investigated by ultraviolet spectrophotometer and visual inspection. When the mass ratio of MWCNTs to PLL is 1:50 and the pH value of the water solution of PLL is 5, MWCNTs can be well dispersed in water.