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Incoherent Neutron Scattering and the Dynamics of Confined Polycarbonate Films



Christopher L. Soles, Jack F. Douglas, Wen-Li Wu, Robert M. Dimeo


Incoherent elastic neutron scattering measurements are performed on thin (1015 to 75 ) polycarbonate films supported on Si wafers. The mean-square atomic displacement is determined by fitting the intensity data to the Debye-Waller factor and we find that is diminished with decreasing film thickness. Two characteristic cross-over temperatures are found in the data, one above and the other below the bulk Tg}, when the film thickness is comparable to the unperturbed dimensions of the macromolecule. Furthermore, the harmonic force constant, defined by the low temperature dependence of , increases for the increasingly thin films. These observations suggest that the atoms are strongly caged in the thin film geometry, thereby hindering the low frequency collective motions.
Physical Review Letters
88 No. 3


confinement, dynamics, glass transition, mean-square displacement, neutron, polycarbonate, thin films


Soles, C. , Douglas, J. , Wu, W. and Dimeo, R. (2002), Incoherent Neutron Scattering and the Dynamics of Confined Polycarbonate Films, Physical Review Letters, [online], (Accessed April 14, 2024)
Created January 1, 2002, Updated February 17, 2017