EFFECT OF REACTOR SIZE ON PLASMA POLYMERIZATION OF PERFLUOROPROPENE

Effects of the reactor size on the deposition characteristics and the chemical structure of deposited polymers during the plasma polymerizat ion of perfluoropropene were investigated. A 132 cm long glass tube wi th a diameter of 1.8, 3.3, or 4.7 cm was chosen for a small, medium, o r large reactor, respectively. Plasma was formed by a capacitively cou pled 13.56 MHz rf power generator. Deposition rate profiles along the reactor tube showed that the dependence of the deposition rate on the operating conditions depended on the reactor size. As the size (diamet er) of a tubular reactor decreases, the dissipation of energy to the r eactor wall increases since the surface to volume ratio of a tubular r eactor increases. Therefore, the plasma polymerization domain changes from the monomer deficient to the energy deficient domain as the react or size decreases under the same (externally controllable) operating c onditions. Electron spectroscopy for chemical analysis was used to ana lyze the chemical composition and structures of deposited polymers. Th e chemical composition and structures were varied depending on the rea ctor size which were also due to the change of the plasma polymerizati on domain. The plasma polymers prepared in the monomer deficient domai n showed a similar composition and structures regardless of the reacto r size or the operating conditions. Generally, large amounts of CF3 an d CF2 groups were present in the polymer prepared in the monomer defic ient domain, and the F/C ratios were approximately 1.6. As the W/FM (e nergy input per unit mass of monomer) value decreased to the energy de ficient domain, the composition and the structures were changed sensit ively but following a complicated pattern according to the change of o perating conditions. (C) 1997 American Vacuum Society.