Thammasat Int. J. Sc. Tech., Vol.13 Special Edition, November 2008 24 Spinnability and Defect Formation of Chitosan/Poly Vinyl Alcohol Electrospun Nanofibers Atipat Chuachamsai, Suwaporn Lertviriyasawat and Panu Danwanichakul Department of Chemical Engineering, Faculty of Engineering, Thammasat University, Rangsit Campus, Khlong-Luang, Pathumthani 12120,Thailand. Email: dpanu@engr.tu.ac.th Abstract This work is focused on the influence of poly vinyl alcohol (PVA) on the formation of chitosan (CS) nanofiber. PVA with different molecular weights, 72,000 and 145,000, and CS with a molecular weight of 180,000 were used. Blend solution was prepared from chitosan and poly vinyl alcohol in water by varying %PVA for a given % of CS. The amount of PVA was varied from 1 to 11 % wt/vol and CS was varied 1 to 3 % wt/vol. It was found that the content of PVA had to be not less than 2% wt/vol to initiate the fiber formation for all chitosan contents. Spinnability was good when using chitosan contents of 1 and 1.5 % wt/vol. PVA with larger molecules seemed to help stabilize the spinnability when increasing the polymer concentration in the appropriate spinnable range and could prevent a sharp increase of nanofiber diameter for the whole range of polymer concentrations. In addition, chitosan/PVA nanofibers seemed to have fewer defects than PVA nanofibers. Keywords: Poly vinyl alcohol, Chitosan, Electrospinning, Nanofibers, Spinnability 1. Introduction Currently, nanofibrous structures can be utilized in many medical applications such as tissue engineering and pharmaceutical purposes. One of the biomaterials that attract much attention for such applications is chitosan, (1-4)- linked 2-amino-2-deoxy-β-D-glucopyranose. It is a polysaccharide derived from chitin, (1-4)- linked 2-acetamido-2-deoxy-β-D-glucopyra- nose. Chitosan is well known for its beneficial properties, for example, haemostatic activity, non-toxicity, biodegradability, and intrinsic antibacterial properties. The use of chitosan is so extensive that its derivatives have also been synthesized and investigated for several properties. For instance, quarternised chitosan was found better than chitosan because of its higher activity against bacteria [1]. The electrospinning method has become a popular method for producing fibers with diameters in the range of a few microns and submicron. It was invented in 1934 to produce polymer filaments by using electrostatic force. When an electric field is applied to the polymer solution, a charged liquid jet exits the capillary tip. The jet with small diameter undergoes stretching and bending instability. After the solvent rapidly evaporates, the fibers left solidify on a collector [2]. The factors affecting spinnability and fiber quality may be classified into process parameters and solution parameters. Process parameters include applied voltage, tip- to-collector distance, and the flow rate, whereas, solution parameters include solution viscosity, surface tension and conductivity. Geng et al. [3] has been the only one group able to electrospin chitosan nanofibers from acetic acid solution. Several groups have tried to do so but never succeeded, including ours. We have attempted to use chitosan with different %DD and found only deposited fine particles instead of nanofibers. Therefore, an easily forming polymer has to be introduced in order to ease the fiber formation. One of most used polymers is poly vinyl alcohol or PVA. It is a non-toxic, water-soluble, biocompatible and biodegradable synthetic polymer which has excellent film forming, emulsifying properties,