Department of Physics, Faculty of Science, National University of Singapore, Singapore, 117542, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 117456, Singapore.
Small. 2015 Mar;11(9-10):1039-54. doi: 10.1002/smll.201402985. Epub 2014 Dec 15.
This review provides a comprehensive survey of the structural characteristics of crystal networks of silk soft fibrous materials in correlation with the macroscopic properties/performance and the network formation mechanisms. The correlation between the hierarchical mesoscopic structures and the mechanical properties of silk soft fibrous materials including silk fibroin hydrogels and naturally spun silk fibers are addressed based on the hierarchical crystal network models. Namely, two types of hierarchical networks are identified: the weak nanofibril-nanofibril interaction case (i.e., silk fibroin hydrogels), and the strong nanofibril-nanofibril interaction case (i.e., silk fibers). The macroscopic properties, i.e., the rheological/mechanical properties, can be controlled in terms of tuning different levels of hierarchical network structures by ultrasonication-induced gelation, introducing the initial nucleation centers, etc. Such controls take effect by different mesoscale assembly pathways, which are found to occur via different routes of the nucleation and growth processes. Furthermore, the hierarchical network model of soft fibrous materials can be applied to explain the superior mechanical properties and the unique strain-hardening behaviors of spider silk fibers within the framework of hierarchical breaking mechanism. Obviously, a knowledge of crystal networks will allow the prediction of the performance and engineering strategy of silk fibrous materials in generals.
这篇综述提供了对丝软纤维材料的晶体网络结构特征与宏观性能/性能和网络形成机制的综合调查。基于分级晶体网络模型，讨论了包括丝素水凝胶和天然纺丝纤维在内的丝软纤维材料的层次状介观结构与机械性能之间的相关性。即，确定了两种类型的分级网络：弱纳米原纤维-纳米原纤维相互作用的情况（即丝素水凝胶），和强纳米原纤维-纳米原纤维相互作用的情况（即丝纤维）。通过超声诱导凝胶化、引入初始成核中心等方法，可以控制不同层次的网络结构，从而控制宏观性能，即流变/力学性能。这些控制作用是通过不同的介观组装途径来实现的，这些途径被发现是通过不同的成核和生长过程的途径发生的。此外，软纤维材料的分级网络模型可以应用于解释蜘蛛丝纤维的优异力学性能和独特的应变硬化行为，在分级断裂机制的框架内。显然，对晶体网络的了解将允许预测丝纤维材料的性能和工程策略。
