Monomers glow-discharge polymerization

The major difference between the cathodic polymerization and the glow discharge polymerization is the influence (or absence) of ion bombardment during the process of material deposition. With an organic compound as monomer, ions that bombard the cathode are mainly those of hydrogen and other non-polymer-forming elements. 

Christy s theory of polymerization by electron bombardment contains an important idea which can be applied to the theory of direct glow discharge polymerization (3). Williams and Hayes emphasized the importance of monomer adsorption to the electrode in the direct method (4). Poll also described the process of film formation in the direct method (. Yasuda et al. employed the indirect method, using an electrodeless discharge, and the results... 

Complex reactions occuring during glow discharge polymerization lead to the formation of materials which should not be simply called polymers obtained from given monomers it would be more appropriate to use the expression plasma-polymerized hexamethylcyclotrisilazane etc. for other monomers but for the sake of simplicity the terms polysilazanes and polysiloxanes will be used in this paper. 

Figure 1. Effect of substrate position on the mass of glow-discharge polymerized propylene, deposited per unit area of Aluminum substrate polymerization time 3 hours, monome flow rates indicated.

Figure 2. Polymerization efficiency of propylene glow discharge polymerization as function of monomer flow rate (from results in Fig. 1).

Plasma or glow discharge polymerization of monomer gases or vapors... 

Because the gas phase changes from a monomer to product gases as soon as glow discharge polymerization occurs, what the product gas plasma does to the system, which consists of the monomer, the intermediate species, a polymer, substrate material, and the wall of the reaction vessel, becomes an important factor. This factor depends on what kind and how much of the product-gas or gases evolve during the process. ... 

When polymer deposition rates are compared for various pairs of monomers, which have similar chemical structures with and without vinyl double bonds, the difference between those with olefinic vinyl double bonds and those without is very smallas shown in Table I. Furthermore, the differences among various kinds of monomers are surprisingly small. In other words, nearly all hydrocarbon monomers polymerize at rates that vary only within an order of magnitude. These two aspects indicate that no specific structure (necessary for the precursor theory) is needed for the glow discharge polymerization of organic compounds. 

Atomic polymerization is not polymerization in the conventional sense, because the molecular structure of the monomers is not retained in the polymer. For instance, the glow discharge polymers of acetylene and benzene are very much alike. Their copolymerization characteristics are nearly identical. When N2 and H2O are added to benzene or acetylene, considering that one molecule of benzene is equivalent to three molecules of acetylene in glow discharge polymerization, nearly identical polymers are formed.(19)... 

---