Alginate hydrogels have garnered significant attention due to their promising applications in the food, biomedical, and pharmaceutical industries. The detection and quantification of distinct water phases within these hydrogels offer valuable insights into their dynamic, absorptive, and mechanical properties. Despite being comprised solely of 2 wt % polymeric materials, the alginate hydrogels exhibit a highly porous morphology, characterized by distinct water pools exhibiting varying mobility and dynamic behaviors. These phases can be delineated as largely free water phase with high mobility, which occupies the macropores, and bound water with restricted mobility, which interacts with the fibrous polymeric structure. Water pools interacting with their surrounding environments possess variable crystal structures on variable freezing points, this could be easily detected using X-ray scattering techniques. A comparative study was conducted based on the information derived from each technique, with differential scanning calorimetry (DSC) yielding quantitative information for the water phases in alginate hydrogels (i.e., 58 % free and 42 % bound water in 0.75 wt % - 6 h aging sample), whereas cryogenic scanning electron microscopy (Cryo-SEM), wide and small-angle X-ray scattering (WAXS and SAXS), Fourier Transform Infrared (FT-IR), and rheology provided valuable qualitative insights. In this study, deep insights into the molecular structure of alginates were obtained including the alteration in morphology and macropore distribution, increase in the wall thickness, density, and mechanical properties upon increasing the Ca concentration and aging period.

中文翻译：

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海藻酸盐水凝胶中不同水池的比较分析研究：定性与定量方法


海藻酸盐水凝胶由于其在食品、生物医学和制药行业的广阔应用而受到广泛关注。这些水凝胶中不同水相的检测和定量为其动态、吸收和机械性能提供了有价值的见解。尽管仅由 2 wt% 的聚合物材料组成，但藻酸盐水凝胶表现出高度多孔的形态，其特征是不同的水池表现出不同的流动性和动态行为。这些相可以被描述为主要具有高流动性的自由水相，其占据大孔，以及具有有限流动性的结合水，其与纤维聚合物结构相互作用。与周围环境相互作用的水池在不同的冰点上具有不同的晶体结构，这可以使用 X 射线散射技术轻松检测到。基于每种技术获得的信息进行了比较研究，差示扫描量热法 (DSC) 产生了藻酸盐水凝胶中水相的定量信息（即，在 0.75 wt % - 老化 6 小时中，58 % 游离水和 42 % 结合水）样品），而低温扫描电子显微镜 (Cryo-SEM)、广角和小角 X 射线散射（WAXS 和 SAXS）、傅立叶变换红外 (FT-IR) 和流变学提供了有价值的定性见解。在这项研究中，深入了解了海藻酸盐的分子结构，包括随着钙浓度和老化时间的增加，形态和大孔分布的改变，壁厚、密度和机械性能的增加。