School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Soft Matter. 2019 Dec 4;15(47):9733-9741. doi: 10.1039/c9sm01789e.
Anisotropic hydrogels are produced, by magnetic alignment of magnetically sensitized nanoclays followed by polymerization of the hydrogel to freeze the developed oriented structure. The anisotropy in these hydrogels is quantitatively investigated using birefringence and 2D small angle X-ray scattering (SAXS) techniques. The oriented nanoclays being intrinsically birefringent provide optical anisotropy to the hydrogel and this orientation increases with the increase of the applied magnetic field strength. Moreover, 2D SAXS patterns also confirm that the nanoclays are oriented parallel to the permanent magnetic field in the hydrogel with an orientation order parameter of up to 0.67. The field-induced birefringence and 2D SAXS orientation results exhibit a linear correlation over the range of 0 to 9 tesla (T). The resultant anisotropic hydrogels exhibit substantial swelling anisotropy, making them suitable for wound dressings where the out of plane swelling is substantially higher than in-plane swelling to minimize in-plane stress damage to the wounds during healing.
各向异性水凝胶是通过对磁敏纳米粘土进行磁场定向排列，然后聚合水凝胶以冻结所形成的定向结构来制备的。使用双折射和二维小角 X 射线散射 (SAXS) 技术对这些水凝胶的各向异性进行定量研究。各向异性水凝胶中的定向纳米粘土具有固有双折射性，从而为水凝胶提供光学各向异性，并且这种定向度随着所施加磁场强度的增加而增加。此外，二维 SAXS 图谱也证实纳米粘土在水凝胶中平行于永磁场取向，取向有序参数高达 0.67。在 0 至 9 特斯拉 (T) 的范围内，场致双折射和二维 SAXS 取向结果表现出线性相关性。所得各向异性水凝胶具有显著的溶胀各向异性，使其适用于伤口敷料，其中平面外溶胀明显高于平面内溶胀，以最大限度地减少愈合过程中平面内应力对伤口的损伤。
