Filamentous Chitosan Mats by Antisolvent Precipitation in the Regime of Turbulent Liquid Mixing

ABSTRACT An effective method has been developed to produce a new class of filamentous chitosan in the form of a mat of fibers of diameters in the micron‐scale range. It is based on a process of antisolvent precipitation of chitosan from solution under turbulent flow shear generated by a high‐speed colloidal mixer. Chitosan microfibers and microribbons of varying sizes were fabricated by adjusting the mixer's rotational speed. XRD and DTA/DSC/TG analyses revealed that the resulting chitosan fibers possess a partially amorphous microstructure, with the degree of amorphization increasing with the stirring speed. Furthermore, the synthesized chitosan microfibers exhibited the ability to reduce silver ions in daylight, facilitated by their highly accessible, high‐surface‐area amorphous structure, resulting in the deposition of silver nanocrystals smaller than 150 nm on their surfaces. Both the filamentous chitosan mats and their silver‐containing nanocomposites were tested against various bacterial strains, with the nanocomposites exhibiting markedly higher antibacterial activity.