Journal
MACROMOLECULAR RAPID COMMUNICATIONS
Volume 36, Issue 15, Pages 1422-1427Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/marc.201500194
Keywords
free surfaces; glass transition; molecular weight; polymers; thin films
Categories
Funding
- Northwestern University
- Dow Chemical Company
- Department of Civil & Environmental Engineering and Mechanical Engineering at Northwestern University
Ask authors/readers for more resources
Nanoscale polymer thin films exhibit strong confinement effects on T-g arising from free surfaces. However, the coupled influence of molecular weight (MW) and surface effects on T-g is not well understood for low MW film systems below the entanglement length. Utilizing atomistically informed coarse-grained molecular dynamics simulations for poly(methyl methacrylate) (PMMA), it is demonstrated that the decrease in free-standing film T-g with respect to bulk is more significant for low MW compared to high MW systems. Investigation of the local interfacial properties reveals that the increase in the local free volume near the free surface is greater for low MW, explaining the MW dependence of T-g-confinement behaviors. These findings corroborate recent experiments on low MW films, and highlight the relationship between nanoconfinement phenomena and local free volume effects arising from free surfaces.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available