Abstract
The dynamics of polymers in an all-polymer nanocomposite that are composed of soft cross-linked polystyrene nanoparticles and linear polystyrene have been investigated. In this article, we describe how the relative size of the nanoparticle to that of the polymer chain and its rigidity impact the linear polymer chain diffusion. The results of the in situ neutron reflectivity experiments show three distinct regimes in the linear polymer diffusion. The results indicate that the inclusion of soft nanoparticles increases the amount of topological constraints and confinement effects for low matrix molecular weight polymer. At modest molecular weights where the size of the nanoparticle and polymer chain are similar, the soft nanoparticles neither inhibit nor enhance the linear polymer diffusion, while at the highest polymer matrix molecular weight, the linear polymer diffusion increases due to an increase in the constraint release mechanism by the soft nanoparticles. Thermal analysis shows that the nanoparticles do not increase the free volume of the system nor do they behave as a plasticizing agent. These results are interpreted to indicate that the competition between a topological barrier effect and enhancing constraint release defines the behavior of a given all-polymer nanocomposite.
| Original language | English |
|---|---|
| Pages (from-to) | 2843-2852 |
| Number of pages | 10 |
| Journal | Macromolecules |
| Volume | 52 |
| Issue number | 7 |
| DOIs | |
| State | Published - Apr 9 2019 |
Funding
This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The authors acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the NR facilities used in this work, where these facilities are supported in part by the National Science Foundation under agreement no. DMR-0944772. The identification of commercial products does not imply endorsement by the National Institute of Standards and Technology nor does it imply that these are the best for the purpose. A portion of this research was also completed at ORNL’s High Flux Isotope Reactor, which was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.
| Funders | Funder number |
|---|---|
| ORNL’s High Flux Isotope Reactor | |
| Office of Basic Energy Sciences | |
| Scientific User Facilities Division | |
| US Department of Energy | |
| National Science Foundation | |
| U.S. Department of Energy | |
| National Institute of Standards and Technology | |
| U.S. Department of Commerce | |
| Office of Science | |
| Basic Energy Sciences | |
| Division of Materials Sciences and Engineering |