Please use this identifier to cite or link to this item:
http://hdl.handle.net/10397/87598
Title: | Deeper penetration of surface effects on particle mobility than on hopping rate in glassy polymer films | Authors: | Lam, C.H. | Issue Date: | 2018 | Source: | Journal of chemical physics, 28 Oct. 2018, 164909, p. 164909-1-164909-13 | Abstract: | Free surfaces in glassy polymer films are known to induce surface mobile layers with enhanced dynamics. Using molecular dynamics simulations of a bead-spring model, we study a wide variety of layer-resolved structural and dynamical properties of polymer films equilibrated at a low temperature. Surface enhancement on thermally induced particle hopping rates is found to terminate abruptly only about 5 particle diameters from the free surface. In contrast, enhancement on the net motions of particles measured at longer time scales penetrates at least 2 particle diameters deeper. The diverse penetration depths show the existence of a peculiar sublayer, referred to as the inner-surface layer, in which surface enhanced mobility is not caused by more frequent particle hops but instead by a reduced dynamic heterogeneity associated with diminished hopping anti-correlations. Confinement effects of the free surface thus provide a unique mechanism for varying the dynamic heterogeneity and hopping correlations while keeping the hopping rate constant. Our results highlight the importance of correlations among elementary motions to glassy slowdown and suggest that dynamic facilitation is mediated via perturbations to the correlations rather than the rate of elementary motions. | Publisher: | American Institute of Physics | Journal: | Journal of chemical physics | ISSN: | 0021-9606 | EISSN: | 1089-7690 | DOI: | 10.1063/1.5052659 | Rights: | © 2018 Author(s). This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in C.H. Lam, J. Chem. Phys. 149, 164909 (2018) and may be found at https://dx.doi.org/10.1063/1.5052659 |
Appears in Collections: | Journal/Magazine Article |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Lam_Deeper_Penetration_Surface.pdf | 3.1 MB | Adobe PDF | View/Open |
Page views
45
Last Week
0
0
Last month
Citations as of Apr 28, 2024
Downloads
33
Citations as of Apr 28, 2024
SCOPUSTM
Citations
8
Citations as of Apr 26, 2024
WEB OF SCIENCETM
Citations
7
Citations as of May 2, 2024
Google ScholarTM
Check
Altmetric
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.