Ref HAL: hal-01207409_v1
Exporter : BibTex | endNote
Résumé:

Carbon nanotubes are widely used as nanocharges in polymer matrix composites for improvingmechanical or electrical properties. Nanocomposites can be prepared either in the solid or in theliquid state, and in the latter case by mixing nanotubes with either melted polymers or polymersolutions. To date, controlled dispersion of CNTs in a solution or a composite remains achallenge, due to the strong van der Waals binding energies associated with the CNTaggregates. Dispersion of nanotubes with high yields, as well as high amounts of individualnanotubes, can be prepared in water with the help of surfactants. However, when using suchsuspensions as precursors for nanocomposites, the final materials will contain some surfactantswhich will influence their physical properties. On the other hand, dispersing nanotubes directlyin polymer solutions without using surfactants leads to low yields and poor individualization.In this work, we propose an alternative and simple way to disperse single-walled carbonnanotubes (SWNT) in aqueous solutions of two hydrosoluble polymers, polyvinyl alcohol (PVA)and polyvinyl pyrrolidone (PVP). We measure the yield using visible-NIR absorptionspectroscopy, and we probe both the chemical environment of the nanotubes and theeffectiveness of individualization from coupled Raman/Photoluminescence studies. First, we mixaqueous suspensions of SWNT stabilized with bile salts (BS) with aqueous solutions of PVA,and we evidence a direct exchange of BS molecules and PVA chains at the surface of SWNT.By contrast, no exchange is observed with PVP. Second, we show that a simple dialysisprocess leads to the preparation of aqueous suspensions of SWNT covered by PVA or PVPwith high yields and an effective individualization of the nanotubes. This simple method opens anew way for preparing surfactant-free polymer matrix composites with high concentrations ofindividual SWNT.