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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.

In order to prepare a cation-exchange membrane, trifluoromethanesulfonic acid (TFMS) and octafluorocyclobutane (OFCB) were plasma-polymerized. Addition of water vapor to the plasma reactor was more effective in preserving the sulfonic acid group in the polymer matrix than was the addition of argon (Ar). Addition of hexafluoropropene (HFP), known as a polymerization promoter, scarcely improved the deposition rate. However, plasma multiphase polymerization, which we called the plasma polymerization process when reactant monomer materials existed in different phases, was effective in accelerating the rate. This technique also increased the ionic conductivity of the resultant plasma polymer.It was found that the polymer film grew uniformly over a 50 cm2 area. A very high ion-exchange capacity of the polymer was obtained using a method that yielded an approximate value.