Department of Biomaterials, Max Planck Institute of Colloids and Interfaces , Wissenschafspark Golm, D-14424 Potsdam, Germany.
Biomacromolecules. 2012 Mar 12;13(3):850-6. doi: 10.1021/bm201764y. Epub 2012 Feb 22.
Agarose hydrogels filled with cellulose nanowhiskers were strained in uniaxial stretching under different humidity conditions. The orientation of the cellulose whiskers was examined before and after testing with an X-ray laboratory source and monitored in situ during loading by synchrotron X-ray diffraction. The aim of this approach was to determine the process parameters for reorienting the cellulose nanowhiskers toward a preferential direction. Results show that a controlled drying of the hydrogel is essential to establish interactions between the matrix and the cellulose nanowhiskers which allow for a stress transfer during stretching and thereby promote their alignment. Rewetting of the sample after reorientation of the cellulose nanowhiskers circumvents a critical increase of stress. This improves the extensibility of the hydrogel and is accompanied by a further moderate alignment of the cellulose nanowhiskers. Following this protocol, cellulose nanowhiskers with an initial random distribution can be reoriented toward a preferential direction, creating anisotropic nanocomposites.
含有纤维素纳米纤维的琼脂糖水凝胶在不同湿度条件下进行单轴拉伸。使用 X 射线实验室源在测试前后检查纤维素纳米纤维的取向，并通过同步加速器 X 射线衍射在加载过程中进行原位监测。这种方法的目的是确定将纤维素纳米纤维重新定向到优选方向的工艺参数。结果表明，水凝胶的受控干燥对于在拉伸过程中建立基质与纤维素纳米纤维之间的相互作用至关重要，从而促进其取向。在纤维素纳米纤维重新取向后对样品进行再润湿可以避免应力的急剧增加。这提高了水凝胶的拉伸性，并伴随着纤维素纳米纤维的进一步适度取向。按照该方案，初始随机分布的纤维素纳米纤维可以重新定向到优选方向，从而形成各向异性纳米复合材料。
