Keywords :
aerogels; Boolean models; gels; scattering data analysis; small-angle scattering; Alginate aerogels; Boolean modeling; Mesoporous solid; Mesoporous structures; Scattering analysis; Scattering data; Scattering data analyse; Small angle scattering; Small-angle neutron scattering; Small-angle scattering; Biochemistry, Genetics and Molecular Biology (all)
Abstract :
[en] Mesoporous polysaccharide aerogels are versatile functional materials for drug delivery and wound dressing devices. The hydration and wetting of these aerogels control their application-related performance, e.g. the release of encapsulated drugs. Reported here is a detailed small-angle neutron scattering (SANS) analysis of the hydration mechanism of a calcium alginate aerogel, based on mathematical modelling of the scattering. The model accounts for the hierarchical structure of the material comprising a mesoporous structure, the solid skeleton of which is made up of water-swollen polymers. At large scale, the mesoporous structure is modelled as a random collection of elongated cylinders, which grow in size as they absorb water and aggregate. The small-scale inner structure of the skeleton is described as a Boolean model of polymer coils, which captures the progressive transition from a dense dry polymer to a fully hydrated gel. Using known physico-chemical characteristics of the alginate, the SANS data are fitted using the size of the cylinders as the only adjustable parameter. The alginate aerogel maintains a nanometre-scale, albeit altered, structure for low water contents but it collapses into micrometre-sized structures when the water content approaches one gram of water per gram of alginate. In addition to the wetting of aerogels, the model might be useful for the small-angle scattering analysis of the supercritical drying of gels.
Funding text :
C. J. Gommes is grateful to the Fonds de la Recherche Scientifique (FRS\u2013FNRS, Belgium) for a Research Associate Position and for supporting this work through grant PDR T.0100.22. Part of this work is based on work from AERoGELS COST Action (ref. CA18125) supported by COST (European Cooperation in Science and Technology), in particular through a stay of Z. Balogh in Li\u00E8ge.
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