Abstract
Changes in the mechanical properties of polymer thin films due to substrate and free surfaces determine the performance of soft nanomaterials. Here we systematically investigate how these interfaces influence the elasticity of supported polymer thin films. Our simulation results demonstrate that the substrate-film interfacial interaction has a strong effect on the elastic response of the films, in which the modulus increases with the strength of interfacial interaction with a nonlinear scaling relationship. The investigation of the local stiffness within the film reveals that there exists an interfacial stiffened region near the substrate and a soft region with reduced stiffness near the free surface. Both regions exhibit similar length scales on the order of nanometers. Our analyses explain the molecular origins of recently observed interfacial stiffening and softening phenomena in polymer thin films, and provide a high-resolution description of the local stiffness gradients in polymer thin films.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 89-95 |
| Number of pages | 7 |
| Journal | Extreme Mechanics Letters |
| Volume | 4 |
| DOIs | |
| State | Published - Sep 1 2015 |
Funding
W.X. and S.K. acknowledge support by the University Partnership Initiative between Northwestern University and The Dow Chemical Company through the award 223029 and from the Dept. of Civil & Environmental Engineering and Mechanical Engineering at Northwestern University. A supercomputing grant from Quest HPC System at Northwestern University is acknowledged.
Keywords
- Coarse-grained simulation
- Elastic modulus
- Interfacial property
- Polymer
- Thin film
ASJC Scopus subject areas
- Bioengineering
- Chemical Engineering (miscellaneous)
- Engineering (miscellaneous)
- Mechanics of Materials
- Mechanical Engineering