Mapping Nanostructural Variations in Silk by Secondary Electron Hyperspectral Imaging

Abstract

Nanostructures underpin the excellent properties of silk. Although the bulk nanocomposition of silks is well studied, direct evidence of the spatial variation of nanocrystalline (ordered) and amorphous (disordered) structures remains elusive. Here, secondary electron hyperspectral imaging can be exploited for direct imaging of hierarchical structures in carbon-based materials, which cannot be revealed by any other standard characterization methods. Through applying this technique to silks from domesticated (Bombyx mori) and wild (Antheraea mylitta) silkworms, a variety of previously unseen features are reported, highlighting the local interplay between ordered and disordered structures. This technique is able to differentiate composition on the nanoscale and enables in-depth studies into the relationship between morphology and performance of these complex biopolymer systems.

Successful development of hierarchical materials relies on the refined organization of repeat units from the nano- to the microscale. Secondary Electron Hyperspectral Imaging (SEHI) addresses a length-scale characterization gap in carbon materials, and is used to highlight the distribution and variation of order/disorder at the nanoscale in model silk materials, providing insight into natural silk spinning.

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