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Neutron scattering in polymer gels at the theta temperature
Author(s) -
Hecht AnneMarie,
Horkay Ferenc,
Mallam Simon,
Geissler Erik
Publication year - 1993
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19930760115
Subject(s) - dispersity , cyclohexane , neutron scattering , polystyrene , compressibility , polymer , small angle neutron scattering , materials science , scattering , swelling , thermodynamics , allowance (engineering) , polymer chemistry , chemistry , physics , optics , composite material , organic chemistry , mechanical engineering , engineering
Small angle elastic neutron scattering was performed on three polystyrene networks swollen to equilibrium in cyclohexane at the theta temperature. Comparison of the SANS spectra with similar measurements in uncross‐linked solutions reveals that in the intermediate Q region the gels behave like solutions of lower concentration than the equivalent solutions. We assume that the gel spectra are composed of a static component plus a dynamic, or solution‐like part. By a suitable fitting procedure, the former can be estimated, yielding the mean square static concentration fluctuation <Δφ 2 > generated by cross‐linking contraints in the gel. Independent measurement of the swelling pressure of these gels permits an estimate to be made of the scattering intensity I(Q=0) of the dynamic part of the spectrum. Plausible agreement is found between the macroscopic and microscopic estimations of the osmotic compressibility if allowance is made for the concentration polydispersity in the gels.