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Moderately concentrated solutions of polystyrene, part 5. Static and dynamic light scattering in bis(2‐ethylhexyl) phthalate
Author(s) -
Yue Shunqiong,
Berry Guy C.
Publication year - 1995
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19950980191
Subject(s) - phthalate , dynamic light scattering , polystyrene , materials science , polymer chemistry , static light scattering , light scattering , polymer science , chemical engineering , scattering , composite material , polymer , optics , physics , nanotechnology , engineering , nanoparticle
Static and dynamic light scattering data are reported on dilute and moderately concentrated solutions of a high molecular weight polystyrene (M w = 3.61 × 10 6 ) in bis(2‐ethylhexyl) phthalate under Flory Theta conditions. The data cover a concentration range with 0.03 × [η]c × 3.5, with several concentrations large enough that the product cM w exceeds the value necessary for entanglement behavior. The results show that a certain intermolecular scattering function H(q, c) often approximated by unity should not be neglected in the evaluation of the correlation length in the static scattering from moderately concentrated solutions of flexible chain polymers. An approximate form for H(q, c) for moderately concentrated solutions is consistent with a soft spherically symmetric repulsive potential among the chains. The dynamic scattering show two distinct groups of relaxation rates at all concentrations, but the interpretation of the two modes changes as the concentration increases from low concentrations ([η]c < 1) to higher concentrations. At low concentrations the slower mode corresponds to mutual diffusion, and the faster mode to intramolecular dynamics. For concentrations with [η]c > 2.4 the slow mode is viscoelastic in origin, and the faster mode is diffusive. The behavior is compared with theoretical predictions in both regimes.