Effect on the processability, structure and mechanical properties of highly dispersed in situ ZnO:CS nanoparticles into PVA electrospun fibers

The main purpose of this work was to synthesize ZnO nanoparticles (NPs) in situ into a chitosan (CS) matrix to obtain highly dispersed antibacterial composites by the sol-gel technique. These composites were characterized by their thermal, structural, morphological and optical properties. NPs were subsequently used and added into polyvinyl alcohol (PVA) in order to obtain electrospun fibers. Previously, it was determined the adequate PVA/CS ratio and changes in their morphological features in dependence of molecular weight of PVA and electrospinning parameters to avoid the beads and spindle-like defects in the final fibers. Then, optimal conditions were used to fabricate PVA/in situ ZnO:CS nanofiber composites. The hydrogen bonding interaction governs the ZnO:CS system, which forms a combination between flower-type and agglomerated rod morphologies. It was found that CS promotes the crystallinity of ZnO NPs maintaining the hexagonal phase. The addition of ZnO into the CS matrix was performed via weak interactions by stabilizing the hybrid compound after the second decomposition stage when the mass loss is above 50%. Free-defects uniform fibers with an improvement in hardness as well as in the elastic modulus was obtained in the electrospun PVA/in situ ZnO:CS fibers. The presence of ZnO NPs improves the spinnability in the fiber nanocomposites with an average diameter of 223 nm. PVA/in situ ZnO:CS mats displayed an inhibition of bacterial growth of Escherichia coli and Staphylococcus aureus.