Dispersions of Polymer-Modified Carbon Nanotubes: A Small-Angle Scattering Investigation
Carbon nanotubes (CNTs) were modified with polystyrene (PS) using self-initiated photografting photopolymerization. In order to optimize their utilization in CNT/polymer nanocomposites, a thorough characterization of their dispersions in solvents is of key importance. Using small-angle scattering, we have studied the effect of the modification on the agglomeration behavior in dilute toluene dispersions. Whereas small-angle X-ray scattering gives overall information, small-angle neutron scattering together with the use of deuterated solvents highlights the polymer shells or the CNTs. The structure of the CNTs and their agglomerates were modeled as fractal aggregates of homogeneous or core−shell cylinders for single- and multiwalled CNTs, respectively. In this way, we have characterized the dispersibility of the CNTs as well as the thickness of the shell formed by the grafted polymers in dependence on the time of polymerization.