Title | NMR experiments and molecular dynamics simulations of the segmental dynamics of polystyrene |
Publication Type | Journal Article |
Year of Publication | 2004 |
Authors | He, Y. Y., T. R. Lutz, M. D. Ediger, C. Ayyagari, D. Bedrov, and G. D. Smith |
Journal | Macromolecules |
Volume | 37 |
Pagination | 5032-5039 |
Date Published | Jun |
ISBN Number | 0024-9297 |
Accession Number | WOS:000222258600041 |
Keywords | 1,4-POLYBUTADIENE MELT, 2-DIMENSIONAL, ATACTIC POLYPROPYLENE MELTS, DIELECTRIC-RELAXATION, EXCHANGE NMR, NEUTRON-SCATTERING, NUCLEAR-MAGNETIC-RESONANCE, POLYMETHYLENE MELTS, SPIN-LATTICE RELAXATION, TEMPERATURE-DEPENDENCE, TETRABLOCK COPOLYMERS |
Abstract | We have performed NMR spin-lattice relaxation experiments and molecular dynamics (MD) computer simulations on atactic polystyrene (a-PS). The segmental correlation times of three different molecular weight a-PS (M-n = 1600, 2100, 10 900 g/mol) were extracted from NMR by measuring the H-2 spin-lattice relaxation times (T-1) over a broad temperature range (390-510 K). MD simulations of an a-PS melt of molecular weight 2200 g/mol were carried out at 475, 500, and 535 K. Comparisons between experiments and simulations show that the MD simulations reproduce both the shape of the P-2(t) orientation autocorrelation function and its temperature dependence, while the simulated segmental correlation times are slower than experimental results by a factor of 1.8. If the simulations are resealed by this factor, they reproduce both the experimental T-1 values and the slight difference in dynamics between the backbone and side group of PS. |
DOI | 10.1021/ma049843r |