School of Chemical Science and Engineering, Fibre and Polymer Technology , Royal Institute of Technology , Teknikringen 56-58 , SE-10044 Stockholm , Sweden.
Wallenberg Wood Science Centre (WWSC) , Teknikringen 56-58 , SE-10044 Stockholm , Sweden.
Biomacromolecules. 2019 Mar 11;20(3):1263-1270. doi: 10.1021/acs.biomac.8b01686. Epub 2019 Feb 8.
The molecular solubility of softwood arabinoglucuronoxylan (AGX) has been thoroughly investigated, and it has been shown that the chemical and physical structures of the extracted hemicellulose are not significantly influenced by different purification steps, but a transient molecular solubility of AGX was observed in aqueous media at low concentrations (1 g/L) when the dissolved macromolecules had a hydrodynamic diameter of up to 10 nm. A phase separation was detected when the concentration was increased to 15 g/L leading to an association of the smaller molecules into fractal structures with a considerably larger diameter, even though the dispersions were still transparent to ocular inspection. Dynamic Light Scattering and Cryo-Transmission Electron Microscopy showed dimensions in the range of 1000 nm. The phase separation of the sample was further characterized by estimating the χ-interaction parameter of AGX in water using the Flory-Huggins theory, and the results supported that water is a poor solvent for AGX. This behavior is crucial when films and hydrogels based on these biopolymers are made, since the association will dramatically affect barrier and mechanical properties of films made from these materials.
已对软木木聚糖阿拉伯半乳聚糖（AGX）的分子溶解度进行了深入研究，结果表明，不同的提纯步骤不会显著影响提取的半纤维素的化学和物理结构，但在低浓度（1 g/L）的水溶液中，当溶解的大分子的流体力学直径达到 10nm 时，AGX 会表现出瞬时的分子溶解度。当浓度增加到 15 g/L 时，会检测到相分离，导致较小的分子缔合成具有相当大直径的分形结构，尽管分散体仍然通过肉眼观察是透明的。动态光散射和冷冻传输电子显微镜显示的尺寸范围在 1000nm 左右。使用 Flory-Huggins 理论估计 AGX 在水中的 χ 相互作用参数，进一步对样品的相分离进行了表征，结果表明水是 AGX 的不良溶剂。当基于这些生物聚合物的薄膜和水凝胶被制备时，这种行为是至关重要的，因为这种缔合将极大地影响由这些材料制成的薄膜的阻隔和机械性能。
