Glow discharge polymerization discussion

There has been a considerable amount of work done on thin film deposition of pure organic vapors by glow discharge polymerization in the past.(4) Hollahan and Rosier(5) have discussed the preparation of inorganic thin films by the glow discharge process, and their uses in the electronics industry. In most cases, the substrate is heated to 200°C or above to form these inorganic films. 

Thompson and Mayhan [190] and Liepins and Sakaoku [191]. Polymerization in an electrodeless glow discharge is discussed in Yasuda and Lamaze [192], and the effect of electric field voltage between two metal plates on the polymerization of vinyl chloride is discussed in Volkov et aL [193]. 

All experimental data in glow discharge polymerization can be interpreted only as circumstantial evidence so far as the mechanism of pol3nner formation is concerned. Therefore, the following discussion presented to support the concept of atomic polymerization is not intended to disprove any... 

Infrared spectra of all glow discharge polymers developed broad absorption bands corresponding to -OH and -i=0 functional groups as storage time elapsed. All polymeric samples, irrespective of the conditions of polymerization showed an increase in mass on exposure to air (which sometimes rises to 25% over a period of 3 months). These results have been discussed in detail elsewhere (20). 

A plasma is an excited gas which consists of atoms, molecules, ions, free radicals, free electrons and metastable species and the use of plasmas to pretreat polymers (and metals, as discussed later) has been known for about 20 years. The plasma may typically be generated in air, termed a corona discharge, or under reduced pressure, termed a glow discharge . Also, the gas may be non-polymerizable or be able to polymerize and deposit onto the substrate surface. A schematic representation [79,80] of the numerous interactions which are possible in a gas plasma impinging upon a substrate is illustrated in Fig. 4.11. 

Strictly speaking, the ususal process of polymerization is not the same as the process that occurs in glow discharge. In this context, polymer formation in a plasma state takes place via a "nonpolymerizing" process. Thus, polymer formation of this type may be characterized as elemental or atomic polymerization in contrast to molecular polymerization, which describes the conventional process. The following discussion may illustrate the atomic nature of polymer formation in a plasma state. 

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