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.

中文翻译：

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海藻酸盐气凝胶的润湿，从介孔固体到水凝胶：小角度散射分析

介孔多糖气凝胶是用于药物输送和伤口敷料装置的多功能功能材料。这些气凝胶的水合和润湿控制其与应用相关的性能，例如封装药物的释放。这里报告的是基于散射数学模型对海藻酸钙气凝胶水合机制的详细小角中子散射 (SANS) 分析。该模型解释了包含介孔结构的材料的分层结构，其固体骨架由水溶胀聚合物组成。在大尺度上，介孔结构被建模为细长圆柱体的随机集合，这些圆柱体随着吸水和聚集而尺寸增大。骨架的小规模内部结构被描述为聚合物线圈的布尔模型，它捕获了从致密干燥聚合物到完全水合凝胶的逐步转变。利用已知的藻酸盐物理化学特性，使用圆柱体的尺寸作为唯一可调节参数来拟合 SANS 数据。海藻酸盐气凝胶在低含水量下保持纳米级结构，尽管发生了改变，但当水含量接近每克海藻酸盐一克水时，它会塌陷成微米级结构。除了气凝胶的润湿之外，该模型还可用于凝胶超临界干燥的小角散射分析。