| 초록 |
Oxidized polyacrylonitrile (PAN) is one kind of semiconducting polymeric material with a strong electrorheological (ER) effect. By controlling the carbonating temperature and time, various oxidized PAN materials of different conductivity and dielectric property can be obtained. They are ideal candidates for investigating the ER mechanism and for making high-performance ER fluids. However, all the oxidized PAN materials already studied were very polydisperse in size and irregular in shape, and there has been no effort to prepare monosized ER fluids of oxidized PAN. To understand ER behaviors more profoundly, morphological interpretation as well as electrochemical investigation is very essential. Therefore, we prepared highly monodisperse PAN microspheres by using two-step seeded polymerization and used them as an ER material after thermal oxidation with different temperatures and times. Size of PAN microspheres was controlled by varying the seed latex size and the monomer swelling ratio during the seeded polymerization procedure. The oxidized PAN particles were characterized by FT-IR spectroscopy, NMR spectroscopy, thermogravimetric analysis, conductivity measurement, and dielectric analysis. The particle morphology was examined by scanning electron microscopy. Finally, ER properties of the oxidized PAN suspensions were investigated in both steady and dynamic modes under various electric fields. |
