Abstract
We measure the dynamics of high molecular weight polystyrene grafted to silica nanoparticles dispersed in semidilute solutions of linear polymer. Structurally, the linear free chains do not penetrate the grafted corona but increase the osmotic pressure of the solution, collapsing the grafted polymer and leading to eventual aggregation of the grafted particles at high matrix concentrations. Dynamically, the relaxations of the grafted polymer are controlled by the solvent viscosity according to the Zimm model on short time scales. On longer time scales, the grafted chains are confined by neighboring grafted chains, preventing full relaxation over the experimental time scale. Adding free linear polymer to the solution does not affect the initial Zimm relaxations of the grafted polymer but does increase the confinement of the grafted chains. Our results elucidate the physics underlying the slow relaxations of grafted polymer.
| Original language | English |
|---|---|
| Pages (from-to) | 7372-7379 |
| Number of pages | 8 |
| Journal | Macromolecules |
| Volume | 50 |
| Issue number | 18 |
| DOIs | |
| State | Published - Sep 26 2017 |
| Externally published | Yes |
Funding
We thank Adeline Mah for help preparing AFM samples, Lisa Liu for suggestions on NSE analysis and many helpful discussions, Dr. Peter Vekilov for access to the AFM instrument, and Dr. Kevin Weiss at SNS for help preparing NSE samples. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. This research at the BL-15 NSE beamline at Oak Ridge National Lab’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE. This work utilized the NIST Center for Neutron Research (NCNR) supported in part by the National Science Foundation (NSF) under Agreement DMR-1508249. The SAXS experiments at UH were performed on an instrument obtained on an NSF grant (NSF DMR 1040446). R.K. acknowledges funding from ExxonMobil Company. J.C.C. acknowledges funding from NSF (CBET-1438204) and the Welch Foundation (E-1869).
| Funders | Funder number |
|---|---|
| Advanced Photon Source | |
| DOE Office of Science | |
| Office of Science User Facility operated | |
| Scientific User Facilities Division | |
| National Science Foundation | DMR-1508249, 1438204 |
| U.S. Department of Energy | |
| Welch Foundation | E-1869 |
| Basic Energy Sciences | |
| Argonne National Laboratory | DE-AC02-06CH11357 |
| Oak Ridge National Laboratory | |
| ExxonMobil Research and Engineering Company | CBET-1438204 |
| NIST Center for Neutron Research |