Multi‐Point Nanoindentation Method to Determine Mechanical Anisotropy in Nanofibrillar Thin Films
Multi‐Point Nanoindentation Method to Determine Mechanical Anisotropy in Nanofibrillar Thin Films
复制标题
多点纳米压痕法测定纳米纤丝薄膜的机械各向异性
DOI：
10.1002/smll.202202065
复制
发表时间：
2022
期刊：
影响因子：
13.3
通讯作者：
Schniepp, Hannes C.
中科院分区：
文献类型：
--
作者：
Perera, Dinidu;Wang, Qijue;Schniepp, Hannes C.
具有优异机械性能的生物材料，包括蜘蛛丝、木材和软骨，通常具有定向纳米纤维结构。纳米原纤维的取向引起显著的机械各向异性，这是非常具有挑战性的特征，特别是对于微观小或不均匀的样品。在这里，一种技术，利用原子力显微镜压痕在多个点结合有限元分析，在一个微观小面积的薄膜样品的机械各向异性的报告。这里研究的系统是智利隐士蜘蛛的带状丝，它完全由严格取向的纳米纤维组成，从而产生较大的机械各向异性。迄今为止，最详细的蜘蛛丝的定向纳米结构-性能表征，揭示了拉伸和横向弹性模量分别为9和1 GPa，丝纳米原纤维之间的结合强度为159±13 MPa。此外，基于该结合强度，纳米原纤维的表面能被推导为37 mJ m−2，并得出结论，货车范德华力在原纤维间的结合中起决定性作用。由于其多功能性，该技术具有许多潜在的应用，包括早期疾病诊断，因为潜在的病理条件可以改变组织的局部机械特性。
Biomaterials with outstanding mechanical properties, including spider silk, wood, and cartilage, often feature an oriented nanofibrillar structure. The orientation of nanofibrils gives rise to a significant mechanical anisotropy, which is extremely challenging to characterize, especially for microscopically small or inhomogeneous samples. Here, a technique utilizing atomic force microscope indentation at multiple points combined with finite element analysis to sample the mechanical anisotropy of a thin film in a microscopically small area is reported. The system studied here is the tape‐like silk of the Chilean recluse spider, which entirely consists of strictly oriented nanofibrils giving rise to a large mechanical anisotropy. The most detailed directional nanoscale structure–property characterization of spider silk to date is presented, revealing the tensile and transverse elastic moduli as 9 and 1 GPa, respectively, and the binding strength between silk nanofibrils as 159±13 MPa. Furthermore, based on this binding strength, the nanofibrils’ surface energy is derived as 37 mJ m−2, and concludes that van der Waals forces play a decisive role in interfibrillar binding. Due to its versatility, this technique has many potential applications, including early disease diagnostics, as underlying pathological conditions can alter the local mechanical properties of tissues.