Determination of the aggregation number of hydrophobic domains in a microphase-separated gel of hydrophobically modified polyacrylic acid

Hydrophobic association in a microphase-separated hydrogel of hydrophobically modified polyacrylic acid is studied by methods of small-angle neutron scattering and fluorescent spectroscopy with the use of pyrene as a probe substance. A fluorescence quenching technique is developed for determining the aggregation numbers of hydrophobic domains in weakly swollen polymeric gels. It is shown that the introduction of charged units into the gel leads to a decrease in the domains’ aggregation number because of the electrostatic repulsion of similarly charged units on their surface.