Nanotechnology-aimed Poymer Synthses using Supercritical Fluids

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Homogeneous polymerizations of tetrafluoroethylenes were executed in supercritical fluoroform, and the morphology of the resulting poly (tetrafluoroethylene)s were observed as the fibrous which were dispersedly and uniformly twined with low density, independent of pressure in the systems. Each piece was ca 100 nm in width and 10 μm in long. The number average of molecular weight and conversions of poly (tetrafluoroethylene) can be controlled by pressure and temperature from 10^4 to 10^6, and 60%-80%, respectively. Heterogeneous detergent, stabilizer-free polymerization can be performed in supercritical supercritical fluoroform/water emulsion. Uniform spherical submicron-particles (200 nm) were obtained, dependent of pressure and water content in the systems.Processing of polymer substrates such as swelling and immersing by supercritical fluids have been studied as a new route to a polymer surface modification. Polymerization of tetrafluoroethylenes (TFE) was carried out in scCO_2 or scCHF_3 in the presence of high density polyethylene (HDPE) and polycarbonate (PC) plates. The surface property was determined by X-ray photoelectron spectroscopy, and its surface energy was estimated by contact angles. Thickness and density of the penetrating PTFE onto substrates depend on conditions of supercritical fluids such as pressure or temperature.