A. I. Drachev

Plasma-chemical synthesis and properties of polymer semiconductors and prospects for their use

The properties and structures of semiconducting polymers prepared by chemical and electrochemical techniques and plasma-synthesized polymer semiconductors were compared. The advantages and disadvantages of these techniques were considered. The potential areas of application of semiconducting polymer films prepared by plasma polymerization were demonstrated.

Charging of Polycarbonate Films in a Direct-Current Discharge

The effect of treatment of Diflon, Makrolon®, and Lexan® polycarbonate films in the cathode fall of a dc discharge was studied. Plasma treatment was shown to result in the hydrophilization of the film surface. The dependence of the contact angle on the discharge current and treatment time was examined. It was found that the discharge induced a negative charge on the polycarbonate surface. The surface-charge density was correlated with the contact angle for various treatment conditions. Space charging processes in glow discharge-treated films were investigated using the thermally stimulated relaxation and depolarization techniques. The role of produced charged entities in an increase in the surface energy of modified polycarbonate films was revealed.

Low-Frequency Glow Discharge Treatment of Poly(ethylene terephthalate) Films

The alteration of surface characteristics of the PET-E poly(ethylene terephthalate) film by treatment in the cathode fall of an ac (50 Hz) glow-discharge plasma was studied. The plasma-assisted modification leads to surface hydrophilization which is retained for a long period of time. It was found that the discharge treatment induced a negative charge in the polymer surface layer. The charge density created under different treatment conditions was correlated with the contact angle. The thermally stimulated relaxation and depolarization measurements on the original and the modified film showed that charge buildup in the film during the discharge treatment was due to trapping of injected electrons. From the experimental data, it was inferred that the charge states emerged play the determining role in enhancing the surface energy of modified PET films.

Low-frequency glow discharge treatment of amorphous poly(ethylene terephthalate) films

The influence of treatment in a low-frequency glow discharge on the surface properties of an amorphous poly(ethylene terephthalate) (PET) film was studied. It was shown that, at identical external discharge parameters, changes in the wettability of plasma-treated PET films depended on its morphological structure—the amorphous film had higher values of the contact angle and lower values of the surface charge density than a biaxially oriented poly(ethylene terephthalate) of the PET-E brand.

Electrophysical Properties of a Poly(ethylene terephthalate) Film Modified in a Cyclohexane Plasma

The structure of a thin layer applied on a poly(ethylene terephthalate) (PET) film using ion-assisted chemical vapor deposition of cyclohexane was studied by electron spectroscopy for chemical analysis and IR spectroscopy. It was found that the film was composed of linear (–СН2–)n chains bearing six-membered cyclohexane rings, including those containing carbonyl groups as substituents, and carbon chains free of H atoms. The plasma-synthesized cyclohexane film was found to be semiconducting. The deposition of a film 10–120 nm in thickness on the surface of PET 30 μm in thickness resulted in an increase in the bulk conductivity over the temperature range 20–200°C and in a considerable increase in the electric strength.

Conducting Polymer Layers Obtained by Direct-Current Discharge Polymerization of 1-Amino-9,10-anthraquinone

The polymerization of 1-amino-9,10-anthraquinone in a direct-current discharge was studied. It was found that polymer films with a conductivity of 10–5–10–4 Ω–1 cm–1 were formed at the cathode. It was assumed that the semiconductor properties are due to the presence of a conjugated cyclic moiety in the films. The layers deposited at the anode turned out to be typical dielectrics with a conductivity of ∼10–16 Ω–1 cm–1.

Generation of Polymer Electrets in a Low-Temperature Glow-Discharge Plasma

The formation of the electret state in polymer materials of various structures in ac and dc discharges was studied. It was found that charges of either sign could be generated in the surface layers of films. The lifetimes of thermoelectrets and discharge-induced electrets are compared. Data on the depth distribution of charge in polymers subjected to electron beam and dc discharge treatment are reported.

Polypropylene Films in a Direct-Current Discharge

The effect of dc discharge treatment on polypropylene films—both commercial and stabilizer- and plasticizer-free as prepared under laboratory conditions (with the rac-Et(Ind)2ZrCl2–methylaluminoxane catalytic system)—was studied. The discharge treatment was shown to hydrophilize the polypropylene surface in both cases. Negative charged states were detected on the modified surface and their relation to the polypropylene hydrophilization was established. By the thermostimulated relaxation and depolarization techniques, it was shown that the observed charges are induced by injection of plasma electrons into the polymer. It was found that severe changes took place throughout the bulk of the polypropylene film synthesized over the metallocene catalyst, as indicated by enhancement of its crystallinity and a change in the molecular mass distribution.

Surface properties of plasma-modified polypropylene and propylene-hexene-1 copolymer films

The surface properties of polypropylene and propylene and hexene-1 copolymers synthesized on the rac-Me2SiInd2ZrCl2-polymethylalumoxane isocpecific metallocene system and the Ph2C(Cp)(Flu)ZrCl2-polymethylalumoxane syndiospecific system were studied. It was found that syndiotactic polypropylene films were less hydrophobic than isotactic polypropylene films, whereas the films of propylene and hexene-1 copolymers were less hydrophobic than the films of corresponding homopolymers. The hydrophobicity of samples decreased with the hexene-1 content of the copolymer. Treatment in a dc discharge resulted in noticeable surface hydrophilization in all of the test polymer samples. There is a correlation between the surface parameters and the density of surface charge induced in the polymers by dc discharge treatment.

Charge Formation on the Surface of a Laminated Polyimide–Fluoroplastic Film by Direct-Current Discharge Treatment

The effect of a direct-current discharge on the tetrafluoroethylene–hexafluoropropylene copolymer (FP) layer of laminated polyimide–fluorocarbon polymer films (including the commercial film PMF-351) placed in the cathode fall was studied. The magnitude of the negative charge induced in the films was shown to be independent of the film thickness. A thermostimulated relaxation curve for the PMF-351 film exhibited two peaks, one at 484 K due to relaxation of the negative charge in the bulk of the FP layer and the other at 417 K characteristic of negative charge relaxation in the polyimide layer. The results are explained by detrapping of electrons by plasma UV radiation that is not absorbable by the FP layer.