Miscible Polyisoprene/Polystyrene Blends: Distinct Segmental Dynamics but Homogeneous Terminal Dynamics

@article{citeulike:2667930, abstract = {Abstract: The segmental and terminal dynamics of the individual components in miscible blends of polyisoprene (PI) and polystyrene (d3PS) were characterized over a wide temperature range. Though the system has a large positive Flory-Huggins interaction parameter ~ 0.1, it is miscible in the temperature range of study due to low molecular weight. 13C and 2H NMR relaxation measurements were performed to extract the segmental relaxation times. Pulse-gradient spin-echo NMR was used to determine the center-of-mass diffusion coefficients. Though the segmental dynamics of PI and PS components differ by more than 2 decades at Tg + 50 K in the blends, their terminal dynamics (in terms of monomeric friction coefficients) are essentially identical. We know of no other system with this behavior. The distinct component segmental dynamics can be reasonably interpreted by the Lodge/McLeish model. The unusual homogeneous terminal dynamics may be due to a large thermodynamic barrier to diffusion in this system. The monomeric friction coefficients are well reproduced by the Gordon-Taylor mixing rule.}, address = {Department of Physics and Maurice Morton Institute of Polymer Science, University of Akron, Akron, Ohio 44325}, author = {He, Y. and Lutz, T. R. and Ediger, M. D. and Pitsikalis, M. and Hadjichristidis, N. and Vonmeerwall, E. D. }, citeulike-article-id = {2667930}, doi = {10.1021/ma0505225}, journal = {Macromolecules}, keywords = {blend, dynamics, nmr, polyisoprene, polystyrene, spatial-inhomogeneity}, month = {July}, number = {14}, pages = {6216--6226}, posted-at = {2008-04-14 15:13:41}, priority = {2}, title = {Miscible Polyisoprene/Polystyrene Blends: Distinct Segmental Dynamics but Homogeneous Terminal Dynamics}, url = {http://dx.doi.org/10.1021/ma0505225}, volume = {38}, year = {2005} }

TY - JOUR ID - citeulike:2667930 L3 - citeulike-article-id:2667930 TI - Miscible Polyisoprene/Polystyrene Blends: Distinct Segmental Dynamics but Homogeneous Terminal Dynamics JF - Macromolecules VL - 38 IS - 14 SP - 6216 EP - 6226 AD - Department of Physics and Maurice Morton Institute of Polymer Science, University of Akron, Akron, Ohio 44325 N2 - Abstract: The segmental and terminal dynamics of the individual components in miscible blends of polyisoprene (PI) and polystyrene (d3PS) were characterized over a wide temperature range. Though the system has a large positive Flory-Huggins interaction parameter ~ 0.1, it is miscible in the temperature range of study due to low molecular weight. 13C and 2H NMR relaxation measurements were performed to extract the segmental relaxation times. Pulse-gradient spin-echo NMR was used to determine the center-of-mass diffusion coefficients. Though the segmental dynamics of PI and PS components differ by more than 2 decades at Tg + 50 K in the blends, their terminal dynamics (in terms of monomeric friction coefficients) are essentially identical. We know of no other system with this behavior. The distinct component segmental dynamics can be reasonably interpreted by the Lodge/McLeish model. The unusual homogeneous terminal dynamics may be due to a large thermodynamic barrier to diffusion in this system. The monomeric friction coefficients are well reproduced by the Gordon-Taylor mixing rule. KW - blend KW - dynamics KW - nmr KW - polyisoprene KW - polystyrene KW - spatial-inhomogeneity AU - He, Y AU - Lutz, TR AU - Ediger, MD AU - Pitsikalis, M AU - Hadjichristidis, N AU - Vonmeerwall, ED PY - 2005/07/12/ UR - http://dx.doi.org/10.1021/ma0505225 ER -