Wide Angle X-Ray Scattering to Study the Atomic Structure of Polymeric Fibers

Natural fibrillar-like macromolecules find applications in several fields, thanks to their peculiar features, and are considered perfect building blocks for natural and artificial functional materials. Indeed, fibrous proteins (such as collagen or fibroin) are commonly used in scaffold fabrication for biomedical applications, due to the high biophysical similarity with the extracellular matrix (ECM) which stimulates tissue regeneration. In the textile industry, cellulose-based fabrics are widely used in place of cotton and viscose, which both have sustainability issues related to their fabrication. With this in mind, the structural characterization of the materials at molecular scale plays a fundamental role in gaining insight into the fiber assembly process. In this work, we report on three fibers of research interest (i.e., type I collagen, silk fibroin extracted from Bombyx mori, and cellulose) to show the power of wide-angle X-ray scattering to characterize both intra- and intermolecular parameters of fibrous polymers. The latest possibilities offered in the X-ray scattering field allow one to study fibers at solid state or dispersed in solutions as well as to perform quantitative scanning X-ray microscopy of tissues entirely or partially made by fibers.