Effects of Substrate Refrigeration on Plasma Polymerization with Fluorocarbons.

Abstract

Effects of refrigeration of substrates during plasma polymerization were investigated with some fluorocarbons. The refrigeration of a substrate stage which worked also as a lower electrode in a plasma reactor changed the phases, gas-liquid-solid, in the reactor in vacuo the same as under normal atmospheric pressure in the case of hexafluoropropene (HFP). The radiofrequency power which was appropriate for yielding a solid polymer was 20-50 W at 230 a K in plasma polymerization of HFP, although the RF power was confined to about 10 W at 300' K. Deposition rates of these polymers were about 180 A /min and 225 A/min, respectively. X-ray photoelectron spectroscopy spectra showed that the reaction proceeded in the presence of a liquid phase HFP. Plasma copolymerization of trifluoromethanesulfonic acid (TFMS), octafluorocyclobutane (OFCB), H2O and HFP was carried out in the temperature range of 250-270' K. The deposition rate and the electrical conductivity were 220 A /min and 4.3 x 10'' ~ 3.3 x 10'S S/cm, respectively, while the same measurements of the copolymer obtained in the range of 300-310 o K were 7 A/min and 2.4 x 10'9^x6.1 x l0~ S/cm. The former included more F atoms than the latter, and it suggested that the plasma ablation and excessive crosslinking were suppressed. The effects seemed to be derived from differences in the plasma activities between the monomers, and the differences were yielded by their different phase, namely, solids of TFMS and H2O, a gas of HFP, and an alternation of a liquid and a gas of OFCB.

Preparation of a Cation-Exchange Membrane from Fluorocarbons by Means of Plasma Multiphase Polymerization.

“…Refrigeration of the substrate to be coated was effective in improving the rate of deposition when monomers that cause polymer ablation coexist in the plasma phase [9]. We have already proposed utilization of the difference in phases between coexisting monomers, which was brought about by refrigeration.…”

“…The plasma reactor system illustrated in Fig. 2 and the polymerization procedure were also identical to those in our previous report [9]. The polymerization was carried out with a radio frequency (RF) power source of 13.56 MHz and sccm (cm3/min under STP) was used as a unit of the monomer flow rate.…”

“…The effect of plasma multiphase polymerization which was carried out by refrigeration of the substrate, the deposition conditions and the electrochemical properties of plasma-polymerized TFMS-OFCB-HFP (PPTOH) are also reported. through the same routes as described in our last report [9]. Reagents used for the evaluation of PPTOH were also described previously [9].…”

“…through the same routes as described in our last report [9]. Reagents used for the evaluation of PPTOH were also described previously [9]. The plasma reactor system illustrated in Fig.…”

“…Therefore, experiments in which the addition of HFP and water vapor instead of Ar along with refrigeration of the substrate upon which the polymer was deposited were carried out. The objective of these experiments was to improve both the rate of deposition and the electrochemical properties of the resultant polymer [9].…”