Dynamics and diffusive-conformational coupling in polymer bulk samples and surfaces: a molecular dynamics study
Vree, C (Vree, C.); Mayr, SG (Mayr, S. G.)
NEW JOURNAL OF PHYSICS, 12: Art. No. 023001 FEB 3 2010
The impact of free surfaces on the mobility and conformational fluctuations of model polymer chains is investigated with the help of classical molecular dynamics simulations over a broad temperature range. Below a critical temperature, T*, similar to the critical temperature of the mode coupling theory, the center-of-mass displacements and temporal fluctuations of the radius of gyration of individual chains-as a fingerprint of structural reconfigurations-reveal a strong enhancement close to surfaces, while this effect diminishes with increasing temperature and observation time. Interpreting conformational fluctuations as a random walk in conformational space, identical activation enthalpies for structural reconfigurations and diffusion are obtained within the error bars in the bulk and at the surfaces, thus indicating a coupling of diffusive and conformational dynamics.
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