Use of contrast-enhanced small-angle neutron scattering to monitor the effects of solvent swelling on the pore structure of styrene-divinylbenzene resins

Hall, P.J. and Galan, D.G. and Machado, W.R. and Mondragon, F. and Barria, E.B. and Sherrington, D.C. and Calo, J.M. (1997) Use of contrast-enhanced small-angle neutron scattering to monitor the effects of solvent swelling on the pore structure of styrene-divinylbenzene resins. Journal of the Chemical Society, Faraday Transactions, 93 (3). pp. 463-466. ISSN 0956-5000 (http://dx.doi.org/10.1039/a605446c)

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Abstract

The pore structure of series of porous styrene-divinylbenzene resins has been monitored both in the non-swollen state and when swollen with a range of solvents of varying Hildebrand solubility parameter using small-angle neutron scattering. It has been shown that the Porod scattering invariants increase as swelling increases, indicating an increase in the interfacial scattering surface area. For the sample prepared with a relatively small amounts of porogen during polymerization, the scattering curves of the acetic acid and toluene swollen samples each consist of two linear regions up to ca. 45 Å is size, corresponding firstly to scattering from swollen, highly crosslinked regions and secondly to mass fractal aggregates of these regions. Samples produced with higher amounts of porogen have a surface fractal structure in the swollen state. Porosity that is closed to the external surface in dry samples is accessible to swelling solvents.