Department of Technical Physics II/Polymer Physics, Institute of Physics, Faculty of Mathematics and Natural Science, Ilmenau University of Technology, PO Box 10 05 65, D-98684 Ilmenau, Germany.
Molecules. 2020 Mar 9;25(5):1227. doi: 10.3390/molecules25051227.
The formation of a rigid porous biopolymer scaffold from aqueous samples of 1% (suspension) and 5% (gel) corn starch was studied using optical and nuclear magnetic resonance (NMR) techniques. The drying process of these systems was observed using a single-sided NMR scanner by application of the Carr-Purcell-Meiboom-Gill pulse sequence at different layer positions. The echo decays were analyzed and spin-spin relaxation times () were obtained for each layer. From the depth dependent relaxation time study, it was found that the molecular mobility of water within the forming porous matrix of these two samples varied notably at different stages of film formation. At an intermediate stage, a gradual decrease in mobility of the emulsion sample towards the air-sample interface was observed, while the gel sample remained homogeneous all along the sample height. At a later stage of drying, heterogeneity in the molecular dynamics was observed in both samples showing low mobility at the bottom part of the sample. A wide-angle X-ray diffraction study confirmed that the structural heterogeneity persisted in the final film obtained from the 5% corn starch aqueous sample, whereas the film obtained from the 1% corn starch in water was structurally homogeneous.
采用光学和核磁共振（NMR）技术研究了由 1%（悬浮液）和 5%（凝胶）玉米淀粉的水样品形成的刚性多孔生物聚合物支架。通过在不同层位置应用 Carr-Purcell-Meiboom-Gill 脉冲序列，使用单面 NMR 扫描仪观察了这些系统的干燥过程。分析了回波衰减，并获得了每层的自旋-自旋弛豫时间（T2）。从深度相关的弛豫时间研究中发现，在成膜的不同阶段，这两种样品中形成的多孔基质内水的分子迁移率有明显的变化。在中间阶段，观察到乳液样品的迁移率朝着空气-样品界面逐渐降低，而凝胶样品在整个样品高度上一直保持均匀。在干燥的后期阶段，两个样品中的分子动力学都表现出不均匀性，表明样品底部的迁移率较低。广角 X 射线衍射研究证实，从 5%玉米淀粉水溶液获得的最终薄膜中存在结构不均匀性，而从 1%玉米淀粉在水中获得的薄膜在结构上是均匀的。
