Preparation and characterization of carbon nanotubes-polymer/Ag hybrid nanocomposites via surface RAFT polymerization

Polymer brushes with multiwalled carbon nanotubes (MWNTs) as backbones were synthesized by grafting 2-hydroxyethyl methacrylate (HEMA) from the sidewall of MWNTs via surface reversible addition and fragmentation chain transfer (RAFT) polymerization using RAFT agent immobilized MWNTs as chain transfer agent. After immobilization of the RAFT agent, poly(2-hydroxyethyl methacrylate) (PHEMA) chains as water-soluble polymer chains were successfully grafted from the surface of MWNTs, resulting in the formation of core-shell nanostructures. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and X-ray photoelectron spectroscopy were used to determine chemical structure and the grafted polymer quantities of the resulting product. Transmission electron microscopy (TEM) images indicated that the nanotubes were coated with a polymer layer. Gel permeation chromatography analyses showed that the molecular weight of cleaved PHEMA increased linearly with the grafted polymer content and the cleaved PHEMA chains had a narrow molecular weight distribution. The PHEMA grafted MWNTs can be hydrolyzed by HCl solution to yield poly(methacrylic acid) (PMAA) grafted MWNTs, which have higher loading capacities for metal ions, such as Ag⁺. TEM and energy dispersive spectroscopy measurements confirmed the nanostructures and the components of the resulting MWNT-PMAA/Ag hybrid nanocomposites.