Electrospinning and Photocrosslinking of Highly Modified Fungal Chitosan

The main focus of this study is to elucidate and optimize the electrospinning process for highly modified fungal chitosan. An efficient one-step process for functionalization of chitosan with arylazide and other desired functional groups via amidation is used for synthesis. Critical electrospinning process parameters, namely, molecular weight, concentration, and ratio of chitosan and additive poly(ethylene oxide) as well as degree of substitution of chitosan are identified by systematic parameter variation following design-of-experiment guidelines. Their influence on the viscoelastic properties of spinning solutions is studied and attributed to changes in chain entanglements. These changes result in drastic shifts in the electrohydrodynamic jet behavior and the resulting fiber morphologies. When the viscosity is increased above a critical limit, complete cancellation of whipping instabilities is observed, resulting in a stable linear jet and highly aligned but partly coalescing microfibers. It is shown how this process conditions can be avoided and how the production of uniform and defect-free nanofibers from highly functional chitosan can be carried out. In addition, a new photocrosslinking method for generation of water and acid stable chitosan nanofiber meshes is established.