Abstract
The structure and dynamics of a model branched polymer was investigated through molecular dynamics simulations and neutron scattering experiments. The polymer confinement, monomer concentration, and solvent quality were varied in the simulations and detailed comparisons between the calculated structural and dynamical properties of the unconfined polymer and those confined within an adsorbing and nonadsorbing cylindrical pore, representing the silica based structural support of the composite, were made. The simulations show a direct relationship in the structure of the polymer and the nonmonotonic dynamics as a function of monomer concentration within an adsorbing cylindrical pore. However, the nonmonotonic behavior disappears for the case of the branched polymer within a nonadsorbing cylindrical pore. Overall, the simulation results are in good agreement with quasi-elastic neutron scattering (QENS) studies of branched poly(ethylenimine) in mesoporous silica (SBA-15) of comparable size, suggesting an approach that can be a useful guide for understanding how to tune porous polymer composites for enhancing desired dynamical and structural behavior targeting carbon dioxide adsorption.
| Original language | English |
|---|---|
| Pages (from-to) | 2617-2625 |
| Number of pages | 9 |
| Journal | Langmuir |
| Volume | 32 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 29 2016 |
Funding
This work is supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by U.S. Department of Energy (US DoE), Office of Science, Basic Energy Sciences (BES) under Award no. DE-SC0012577. The authors acknowledge the Center for Accelerated Materials Modeling (CAMM) funded by US DoE, BES, Materials Science and Engineering Division (MSED) for helping with the analysis of MD simulations data and the support of the National Institute of Standards and Technology (NIST), U.S. Department of Commerce (US DoC), in providing the neutron research facilities used in this work. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF) at the Oak Ridge National Laboratory (ORNL), which is supported by the Office of Science of the U.S. DoE under Contract No. DE-AC05-00OR22725. QENS measurements were performed on BASIS at the Spallation Neutron Source (SNS) at ORNL and at the High Flux Backscattering Spectrometer (HFBS) at the NIST Center for Neutron Research (NCNR) at NIST (Gaithersburg, MD, USA). The authors would like to thank S. O. Diallo and M. Tyagi for their discussion and assistance in performing experiments on the BASIS and HFBS spectrometers, respectively. This work utilized facilities supported in part by the National Science Foundation under Agreement No. DMR-1508249.