We utilize inelastic incoherent neutron scattering (INS) to quantify how fullerenes affect the fast molecular dynamics of a family of polystyrene related macromolecules.. Apparent Debye-Waller (DW) factors are determined as a function of temperature, characterizing the amplitude of proton vibrations , (mean-square displacement). The addition of C60 to these polymers leads to a progressive increase of relative to the pure polymer value over the entire temperature range investigated, where the effect is larger the larger the nanoparticle concentration. This general trend seems to indicate that the C60 nanoparticles plasticize these polymer glasses.Recently, Kropka et al. [Macromolecules 40, 5424 (2007)] performed INS measurements on C60 dispersed in poly(methyl methacrylate) and a reported a decreased amplitude of atomic motions in this polymer material, so that nanoparticle plasticization of polymers is not universal. The situation with these additives is evidently similar to polymer films in the sense that the high interfacial area leads to a change in the liquid dynamics that can cause both a speeding up and slowing down of the liquid dynamics depending on the polymer-surface interaction.
Citation: Journal of Physics C-Solid State Physics
Pub Type: Journals
Debye-Waller factor, fullerene, glass formation, incoherent neutron scattering, nanoparticles, plasticization, polymer melts, polystyrene