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Small‐angle X‐ray scattering studies on polymer chain conformations in concentrated solutions and in bulk
Author(s) -
Hamada F.,
Hayashi H.,
Nakajima A.
Publication year - 1978
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889878013771
Subject(s) - polymer , radius of gyration , scattering , polystyrene , solvent , random coil , small angle scattering , wide angle x ray scattering , chemistry , theta solvent , small angle x ray scattering , materials science , chemical physics , crystallography , analytical chemistry (journal) , polymer chemistry , small angle neutron scattering , neutron scattering , solvent effects , organic chemistry , physics , optics , circular dichroism
The use of the polymers tagged with heavy atoms in random positions along the chains (randomly tagged polymers) in small‐angle X‐ray scattering is proposed as a new method for measuring the chain conformations in concentrated solutions and in bulk polymers. The experimentally determined excess scattering from the tagged chains dispersed in the system is shown to be proportional to the scattering function of the hypothetical chains that have no tags but have the conformation of the tagged chains when the heavy atoms have sufficiently large scattering power. It has been experimentally verified that the effect of the tags on the chain conformation can be eliminated by the extrapolation of the apparent values, measured for a series of tagged polymers with various tag content, to zero tag content. The radii of gyration of the polystyrene chains ( M = 1.1 × 10 5 ) in the bulk and in concentrated solutions in a good solvent and a θ ‐solvent have been determined. The chain dimension in a good solvent (toluene at 25°C) decreases rapidly first and then gradually approaches the unperturbed dimension with increasing polymer concentration. The dimension in a θ ‐solvent ( trans ‐decalin at 21.2°C) is independent of the polymer concentration. The conformation of the polystyrene chains in the bulk was found to be a Gaussian coil.