Inductively coupled plasma reactor polymerization

There are two important questions which may readily be addressed by ESCA. Firstly, what is the rate of deposition of the polymer film at a given site in a plasma reactor and secondly how does the structure depend on the site of deposition To illustrate the great power of the technique in answering these questions we consider here a recent detailed investigation of the inductively coupled plasma polymerization of pentafluorobenzene (13). 

Ray et al. [24] treated Cloisite 20A (montmorillonite modified with dimethyl-ditallow-containing approximately 65% Cig, 30% Cis, and 5% Ci4-ammonium cation chains) with a MAO solution, after vacuo-drying at 100 °C. The resulting MAO-treated clay was subsequently used for ethylene polymerizahon in the presence of a late transition metal catalyst (2,6-bis[l-(2,6-diisopropylphenylimino)ethyl] pyridine iron(ll) dichloride) and additional MAO in a glass reactor. They compared the result with homogeneous polymerization with the same catalyst in the presence of Cloisite 20A and observed that the supported catalyst was more efficiently exfoliated than when only a mixture of catalyst and clay was used. This comparison led them to conclude that at least some of the active centers resided within the clay galleries. Inductively coupled plasma (ICP) measurements showed that all MAO and catalyst remained in the solid catalyst after drying. 

Continuous production of fullerenes was possible by pyrolysis of acetylene vapor in a radio-frequency induction heated cylinder of glassy polymeric carbon having multiple holes through which the gas mixture passes [44]. Fullerene production is seen at temperatures not exceeding 1500 K. The yield of fullerenes, however, generated by this method is less than 1%. A more efficient synthesis (up to 4.1% yield) was carried out in an inductively coupled radio-frequency thermal plasma reactor [45]. 

Because an electrode does not function as electrode in DC or alternating current high-frequency discharge, the electrode system could be kept outside a glass reactor (capacitive external electrodes) or a coil around a glass tube (inductively coupled external electrode) can be used to create plasma. These modes of coupling could be dealt as a factor in the system-dependent aspect of plasma polymerization, i.e., the basic plasma polymerization remains the same. 

A capacitively coupled reactor designed to permit continuous coating of a moving substrate with plasma polymer has been described [ 1 ]. In this paper the results of a study of the plasma polymerization of tetrafluoroethylene in such a reactor presented. Plasma polymer has been deposited on aluminum electrodes as well as on an aluminum foil substrate placed midway between electrodes. The study particularly explores conditions in which deposition is minimized on the electrode. For this reason the chemical nature of the polymer formed in a low flow rate (F = 2 cm (S.T.P.)/min) and low pressure (p = 60 mlllltorr) plasma has been analyzed by the use of ESCA (electron spectroscopy for chemical analysis) and deposition rate determinations. This method combined with the unusual characteristics of TFE plasma polymerization (described below) has yielded Information concerning the distribution of power in the inter-electrode gap. The effects of frequency (13.56 MHz, 10 KHz and 60 Hz), power and magnetic field have been elucidated. The properties of the TFE plasma polymer prepared in this apparatus are compared to those of the plasma polymer deposited in an inductively coupled apparatus [2,3]. 

We may compare results presented here with those obtained in two types of inductively coupled reactors [, 3]. One is the reactor we have used for many years [4], in which the portion of the reactor inserted into the r.f. coil is smaller than the main portion of the reactor, in which plasma polymer is collected. Monomer flux is directed into the main portion of the reactor, not through the r.f. coil. Electron bombardment of plasma polymer and substrate is reduced in this way [ ]. Active species are formed mainly under the r.f. coll and are transported by diffusion to the entire volume of the reactor. Interaction of these non-polymerizable energy carrying species (e.g. electrons, excited atoms) with the monomer entering the reactor leads to plasma polymerization [ ]. 

A long tube with the coupling coil at the middle was used for the plasma polymerization of TFE in an inductively coupled radio-frequency glow discharge using a flow system. Deposition rates and the chemical nature of the polymer were detected as a function of location in the reactor tube relative to the coupling coil and of applied... 

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