Preparation And Properties Of Ultrafine Fibers From Chitosan/Poly(Vinyl Alcohol) By Electrospinning

Electrospinning is process that produces polymer fibers with sub-micron diameters. With high specific surface and low diameter, electrospun fibers have a broad range of potential applications such as tissue engineering scaffolds, filters, wound dressings. Because chitosan could not be electrospun in an aqueous acetic acid (HAc) solution, poly(vinyl alcohol) (PVA) was added as a "guest" polymer to improve the spinnability of chitosan. In this work, electrospinning of chitosan/PVA in aqueous HAc solutions was studied. The properties of the chitosan/PVA solutions including viscosity, conductivity and surface tension were measured and discussed. The influence of concentration of solution and solvent, the mass ratio of chitosan to PVA, processing parameters (voltage, flow rate, distance from tip to collector) on the spinnability of chitosan/PVA solutions and morphology of electrospun chitosan/PVA fibers were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The molecular interaction between chitosan and PVA was investigated by Fourier transformed infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The components of beads and fibers in electrospun fibers were investigated by electron diffraction spectrometry (EDS). The water uptake of the fibrous membranes was also measured. The results showed that the electrospun chitosan/PVA fibers could successfully produced via elelctrospinning. The viscosity, chitosan/PVA mass ratio were the main factors influencing the spinnability of chitosan/PVA solution and morphology of the electrospun chitosan/PVA. When the solution viscosity was among 4.00-10.00 Pa·s and the content of chitosan was below 60%, it was found that the fibrous membrane was generated in a round shape on the collection screen. The diameter of chitosan/PVA fibers was 50-200 nm, the diameter of beads was 200-500 nm. EDS verified that the beads and fibers had nitrogen element, namely chitosan ultrafine fibers were obtained by the blend method with PVA. From FT-IR, XRD and DSC analyses, chitosan and PVA have good miscibility and compatibility in HAc. The hydrogen bond between chitosan and PVA macromolecules decreased the interruptive action of amido to process of elelctrospinning. The addition of PVA also increased the water uptake of electrospun membranes from 27.6% to151.6%.