Space-Dependent Dynamics in 1,4-Polybutadiene Nanocomposite

Published

August 16, 2013

Author(s)

J.H. Roh, Madhu Sudan Tyagi, T. E. Hogan, C. M. Roland

Abstract

Neutron backscattering measurements were carried out on 1,4-polybutadiene, neat and bound to carbon nanoparticles. At large length scales (> 6Å), the Gaussian approximation holds: τ^Β_α ∝Q^-2 where τ_α is the segmental relaxation time, β the Kohlrausch stretch exponent, and Q the wavevector. Both materials exhibit a temperature-independent crossover to relaxation that is nearly wavevector invariant at higher Q. As also shown by mechanical and dielectric spectra, binding to the particles slows down the segmental relaxation and enhances the heterogeneous character of the polymer dynamics. However, the neutron scattering data reveal that this heterogeneity introduces a marked Q-dependence of β. Both the stretching of the relaxation and the relaxation time are larger for the nanocomposite, with the slowing down of the dynamics primarily at larger Q. The latter reflects the fact that the effect of binding of chains to the particles depends on the proximity of a segment to the binding site.

Citation

Macromolecules

Volume

46

Pub Type

Journals

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Keywords

Polymer dynamics, neutron scattering, diffusion, confinement

Citation

Roh, J. , Tyagi, M. , Hogan, T. and Roland, C. (2013), Space-Dependent Dynamics in 1,4-Polybutadiene Nanocomposite, Macromolecules, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=914389 (Accessed June 7, 2023)