Low-pressure oxygen plasma

Once the contaminants have been removed, the virgin polymer surface is exposed to the plasma environment. The electrons, ions, and free radicals in the plasma act on this exposed polymer, creating free radicals in the molecular chains on the surface [1,22,23]. The free radicals that are created on the polymer surface by this process can then react with the various molecular and active species present in the plasma environment. In a low-pressure oxygen plasma, the following oxidation reaction scheme has been suggested ... 

Stokes et al. 47) reported similar conversions of oxygen in air to nitrogen oxides in a low-pressure RF plasma. After a run time of 2.5 hr, 0.4 ml of material was collected in liquid nitrogen traps, which on analysis showed a 2% conversion to nitric oxide. LaRoche 36) had previously demonstrated the beneficial effect of quenching the reaction products. In experiments with a low-pressure RF discharge, he obtained an increase in conversion to nitric oxide from 2 to 4% by a rapid quenching technique. 

The experimental approach was outlined in Sec. 2.3. HyperthermaJ beams of energy selected Ar atoms or N2 molecules were directed at polymer surfaces that were continously bathed with the effluent of a low pressure RF plasma source of oxygen atoms (see Fig. 7). Interaction of the effusive 0-atom beam with polymer samples produced both CO and CO 2 continuously, and data were collected under conditions of steady-state oxidation, as verified by the unchanging signals from CO and CO2 in the mass spectrometer. Product TOF distributions were collected at m/z = 28(CO+) and 44(002 ), following impingement of hyperthermaJ beam pulses on polymer surfaces that had reached a steady state of oxidation. 

Solution polymerization of VDE in fluorinated and fluorochlorinated hydrocarbons such as CEC-113 and initiated with organic peroxides (99), especially bis(perfluoropropionyl) peroxide (100), has been claimed. Radiation-induced polymerization of VDE has also been investigated (101,102). Alkylboron compounds activated by oxygen initiate VDE polymerization in water or organic solvents (103,104). Microwave-stimulated, low pressure plasma polymerization of VDE gives polymer film that is <10 pm thick (105). Highly regular PVDE polymer with minimized defect stmcture was synthesized and claimed (106). Perdeuterated PVDE has also been prepared and described (107). 

Gas plasma treatment operates at low pressure and relatively low temperature. While the corona treatment is applicable to substrates in sheet or film form, the gas plasma process can treat objects of virtually any shape. The gases most widely used to generate plasma by free-radical reactions include air, argon, helium, nitrogen, and oxygen. All these, with the exception of oxygen. 

Another MOCVD reaction uses a microwave plasma to decompose iron cyclopentadienyl, (C5H5)2Fe, in an oxygen atmosphere in a temperature range of 300-500°C and at low pressure (1-20 Torr).[39]... 

Low-pressure RF gas plasma is effective to enhance the adhesion of SBR and Oxygen,... 

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