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Concentration polydispersity in polymer gels
Author(s) -
Geissler Erik,
Horkay Ferenc,
Hecht AnneMarie
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.19950930108
Subject(s) - dispersity , small angle x ray scattering , materials science , polymer , neutron scattering , scattering , elastic modulus , osmotic pressure , swelling , chemical physics , small angle neutron scattering , thermodynamics , chemistry , polymer chemistry , composite material , physics , optics , biochemistry
For swollen polymer networks there is no generally accepted relation between the macroscopic osmotic properties and the scattering behaviour. Detailed information on the relationship between these properties can, however, be deduced from complementary measurements of osmotic and elastic behaviour, small angle neutron and X‐ray scattering (SANS and SAXS) and quasi‐elastic light scattering. We describe such an investigation in two types of networks, differing in the mechanism of cross‐linking. The SANS spectra yield information on the structure, which is generated both by the dynamics of the system and by long range static constraints. The former, arising from thermodynamic concentration fluctuations, governs the macroscopic osmotic and elastic moduli of the swollen network. The static superstructure in the gel reflects local variations in the cross‐link density. The resulting concentration polydispersity, <δφ 2 >/φ 2 , is determined by the details of the cross‐linking procedure. Its concentration dependence as a function of gel swelling can be expressed in terms of the same macroscopic osmotic and elastic variables as those that govern the thermodynamic properties of the gel.