Atomic Force Microscopy Characterization of Cellulose Nanocrystals
Atomic Force Microscopy Characterization of Cellulose Nanocrystals
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DOI：
10.1021/la903111j
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发表时间：
2010-03-16
期刊：
影响因子：
3.9
通讯作者：
Moon, Robert J.
中科院分区：
文献类型：
--
作者：
Lahiji, Roya R.;Xu, Xin;Moon, Robert J.
纤维素纳米晶体（CNC）作为一种“绿色”纳米材料，具有优异的上级机械和化学性能，可用于高性能纳米复合材料，但目前还缺乏对单个CNC的准确材料性能表征。在这里，一个详细的研究的地形，弹性和粘合性能的个别木材衍生的CNC使用原子力显微镜（AFM）进行。AFM实验，涉及高分辨率的动态模式成像和跳跃模式的测量进行个别CNC在30%的相对湿度（RH）的环境条件下，在0.1%RH的N-2气氛下。还开发了一个程序来计算CNC横向弹性模量（E-T）通过比较实验力-距离曲线上测得的CNC上的尖端压痕的三维有限元计算。在0.1%RH下，所有分离CNC的E-T估计在18和50 GPa之间;然而，无法确定CNC的相关晶体学取向。CNC性能沿整个CNC长度是合理均匀的沿着，尽管CNC高度沿3-8轮辋的轴沿着变化。发现本研究中使用的RH范围对CNC几何形状的影响最小，证实了纤维素晶体对水渗透的抵抗力。CNC的灵活性也进行了研究，通过使用原子力显微镜针尖作为nanomanipulator。
Cellulose nanocrystals (CNCs) are gaining interest as a "green" nanomaterial with superior mechanical and chemical properties for high-performance nanocomposite materials; however, there is a lack of accurate material property characterization of individual CNCs. Here, a detailed Study of the topography, elastic and adhesive properties of individual wood-derived CNCs is performed using atomic force microscopy (AFM). AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs under ambient conditions with 30% relative humidity (RH) and under a N-2 atmosphere with 0.1% RH. A procedure was also developed to calculate the CNC transverse elastic modulus (E-T) by comparing the experimental force-distance curves measured on the CNCs with 3D finite element calculations of tip indentation on the CNC. The E-T of ail isolated CNC was estimated to be between 18 and 50 GPa at 0.1% RH; however, the associated crystallographic orientation of the CNC could not be determined. CNC properties were reasonably uniform along the entire CNC length, despite variations along the axis of 3-8 rim in CNC height. The range of RH used in this study was found to have a minimal effect oil the CNC geometry, confirming the resistance of the cellulose crystals to water penetration. CNC flexibility was also investigated by using the AFM tip as a nanomanipulator.