Plasma initiated copolymerization

Figure 1. Monomer—copolymer composition relationship for the plasma-initiated copolymerization of methyl methacrylate with styrene. Plasma-initiated polymerization (%) NMR, (x) elemental analysis. Thermal polymerization (O) NMR, (Aj elemental analysis, (—) theoretical curve, tmma = 0.46 =...

Table 2. Plasma-Initiated Copolymerization of Methyl Methacrylate and Styrene ...

By means of OH- and COOH-containing plasma polymer layers the quahfica-tion of these layers as models of single-type functionalized adhesion promoters with variable concentrations of functional groups should be proved. The plasma-initiated copolymerization of acrylic acid with ethylene or 1,3-butadiene is shown in terms of measured COOH concentration as a function of the composition of the comonomer mixture in Fig. 18.3. Depending on the co-monomer reactivity, a more linear correlation (butadiene), or a parabolic behavior (ethylene), between precursor composition and COOH groups produced was observed. For each type and concentration of functional group, its concentration was determined by chemical derivatization followed by XPS analysis as described in Section 18.2.5. 

A more complicated but very variable process (iii) was the pulsed plasma-initiated polymerization or copolymerization. Here, the desired monotype functional groups are provided by the monomer, which are polymerized in the pulsed plasma. The art in producing such 50 nm thick monotype functionalized polymer coatings lays in carrying out the plasma process under as mild conditions as possible to avoid fragmentation of monomers and to preserve and remain the functional groups of the respective monomers. 

As shown in Fig. 8, similar tendencies were detected considering the allyl alcohol copolymerization with ethylene, butadiene or styrene. Here, different curve progressions are observed depending on the types of comonomers, their ratio in the precursor mixture, and the plasma parameters. These deviations were attributed to the different tendencies to undergo a copolymerization, for example expressed in copolymerization parameters, which are also valid for the plasma-initiated gasphase copolymerization. 

Plasma-Initiated Polymerization and Copolymerization of Liquid Vinyl Monomers... 

The graft copolymerization of many monomers onto cellulose and onto cellulose derivatives has been carried out by different methods that can be generally classified into three major groups (i) chemical methods, (ii) radiation-induced grafting, and (iii) plasma-initiated grafting [11]. 

It is important to pay attention to the potential role of peroxides created on the surface of plasma-treated, including plasma polymer-coated, TPOs in the formation of durable bonds between the substrate and primer. It has been known for decades that the peroxides formed on the irradiated polymers (by y-ray. X-ray, electron beams, etc.) can be utilized in graft copolymerization of various monomers. This method is known as the peroxide method of radiation copolymerization [27]. The trunk polymer is first irradiated by ionizing radiation in a vacuum or in an inert gas environment. The irradiated polymer is exposed to air or oxygen to convert free radicals to peroxides. Thus created peroxides-containing polymers were used as the initiator of the free radical polymerization of the second monomer. The polymer peroxides are decomposed by heat or by the use of reduction/oxidation accelerator, i.e., peroxides are converted to free radicals. 

The oxygen-free plasma-induced graft copolymerization with free radicals was extensively studied by Pales and his coworkers primarily in order to improve the dyeability of fibers, whereas very little is known about the graft copolymerization initiated by peroxide formed from oxygen The plasma-induced graft copolymerization via peroxide formation is briefly described below... 

Pre-activate polymer substrate (e.g., by peroxidation in air or ozone) using plasma discharge, ioniring radiation or chemical treatment, llien contact with monometfs) solvents and initiate using heat and/or catalyst to graft copolymerize monomer onto polymer substrate. Remove solvent and any unreacted monomer. ( Indirect Method )... 

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