Laurati M, Sotta P, Long DR, Fillot LA, Arbe A, Alegria A, Embs JP, Unruh T, Schneider GJ, Colmenero J (2012)
Publication Status: Published
Publication Type: Journal article
Publication year: 2012
Publisher: AMER CHEMICAL SOC
Book Volume: 45
Pages Range: 1676-1687
Journal Issue: 3
DOI: 10.1021/ma202368x
We investigate the dynamics of water absorbed in amorphous and semicrystalline aromatic polyamide copolymers. The combination of dielectric spectroscopy and quasi-elastic neutron scattering experiments allows us to characterize the water dynamics over a wide range of temperatures (dielectric spectroscopy) and at microscopic length scales (neutron scattering). The dielectric investigation evidences two relaxations associated with water motions: a fast process corresponding to motions of loosely bonded water molecules and a slower process corresponding to motions of amide-water complexes. While the slower process presents the characteristic Arrhenius temperature dependence of a secondary local relaxation over the whole temperature range, the fast process shows a crossover from Arrhenius to Vogel-Fulcher-Tamman (VFT) behavior at T approximate to 225 K, characteristic of confined water dynamics. The microscopic investigation by neutron scattering shows than in the VFT regime of the fast process the dynamics present a diffusive nature similar to bulk water. A large distribution of diffusion coefficients indicates possible differences in the connectivity of the hydrogen bond network. Diffusive heterogeneous dynamics can arise from a nonuniform distribution of water. The confinement effect of the polymer matrix is detected as a considerable reduction of the diffusion coefficient of water with respect to bulk. The presence of a crystalline phase results in a slowing down of both the fast and slow processes involving water motions. This could give a hint to the presence of a rigid amorphous phase in the semicrystalline material.
APA:
Laurati, M., Sotta, P., Long, D.R., Fillot, L.A., Arbe, A., Alegria, A.,... Colmenero, J. (2012). Dynamics of Water Absorbed in Polyamides. Macromolecules, 45(3), 1676-1687. https://doi.org/10.1021/ma202368x
MLA:
Laurati, M., et al. "Dynamics of Water Absorbed in Polyamides." Macromolecules 45.3 (2012): 1676-1687.
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