Preparation and Characterization of Alginate Electrospun Nanofibers
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Preparation and Characterization of Alginate Electrospun Nanofibers Tae H. Oh1, Young H. Seo1, Jin W. Cha1, Young M. Im1, Jun S. Hwang1, Joseph A. Nathanael1, and Ssang S. Kim2 1 Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan 712749, Republic of Korea 2 Jungwoo Textile, Nonsan 320872, Republic of Korea ABSTRACT To modify the rigid structure of alginate, polyvinyl alcohol was mixed. Rheological properties and viscoelastic properties of the polymer blend solution were investigated. Complex and shear viscosity and tangent delta of the solution were obtained to find optimum condition of spinning dope. Effect of blend ratio on morphology and property change was investigated. INTRODUCTION Alginate is known to have superior biocompatibility and hence can be used for biomedical application such as scaffold, wound dressing, suture and so on [1-3]. However, it is difficult to prepare homo alginate fibers due to its rigid chemical structure. In this work, the polyvinyl alcohol (PVA) was blended with alginate to enhance spinnability. Complex and shear viscosity, tangent delta of the polymer blend solution were obtained to find optimum condition of spinning dope and the effect of blend ratio on morphology was investigated. EXPERIMENTAL Base polymer was PVA, of which the degree of polymerization was 1,700 and the degree of saponification was 99.9%. Sodium alginate was purchased from Sigma Aldrich Co. Ltd. Distilled water is used for solvent. Polymer concentrations of each polymer were 11.0 wt% for PVA and 4.0wt% for sodium alginate, respectively. Blend ratio based on volume (PVA/Alginate) was changed with 1/1, 1/2, and 2/1. Electro spinning conditions were fixed after several optimizing experiments. Flow rate, tip to collector distance and applied voltage were 0.1 ml/h, 10 cm, and 20 kV, respectively. DISCUSSION Rheological properties of PVA/alginate blend solution are shown in figure 1. Complex and shear viscosity and tangent delta obtained from storage (G’) and loss modulus (G”) are shown. Complex and shear viscosity show shear thinning behavior like general spinnable polymer solution viscosity. In figure 1(b), Newtonian like viscosity ranges maintains up to 10 sec-1. Tangent delta (G”/G’) values are larger than unity (figure 1(c)) for whole frequency ranges indicating not the formation of polymer gel but that of stable polymer solution.
Figure 1. Rheological properties of PVA/Alginate nanofibers; (a) complex viscosity, (b) shear viscosity, and (c) tangent delta.
Transmittance (a.u.)
FT-IR spectra of PVA/alginate blend nanofibers are shown in figure 2. The peaks for PVA [4] are a band at 2800-3000 cm-1 for stretching vibrations of CH and CH2 groups, a band at 13001500 cm-1 for CH/CH2 deformation vibrations, a broad hydroxyl band at 3000-3600 cm-1, and CO stretching at 1000-1200 cm-1. The characteristic peak for alginate is a band at 1601 cm-1 for carboxylate salt group [5]. As PVA blend ratio increases, the intensity of –OH stretching and – CH stretching bands increases and the peak at 16
