Surface modification of polystyrene derivatives by ozone (O3) was investigated by in situ FT-IR spectroscopy. Polystyrene (PS) and its derivatives, poly (4-methyl polystyrene)(P4MS) and poly (α-methyl polystyrene)(PαMS) were used to compare the surface modification by O3 at different temperatures. Polymer film of 5 µm thickness was exposed to 3026 ppm of gaseous O3 in the FT-IR cell heated in the range of 0–70◦ C. Then, in situ FT-IR spectra of these films were measured under O3 exposure. It was found that the IR band assigned to C= O stretching appeared in PS and P4MS with a weak dependence on temperature; but the appearance of the C= O band was strongly dependent on temperature in the case of PαMS. The O3 reactivity of PαMS was rather lower than that of polyethylene (PE). These results strongly suggested that thermally decomposed O3 species attacked the main chain of the PS and P4MS at high temperatures. Furthermore, we investigated the surface properties of these polymer films before and after the O3 modification by AFM and water contact angle. Evidence was shown that thermal ozonolysis process for PαMS having methyl group on the polymer main chain was depressed.

The capacity of a cold atmospheric-pressure air plasma (CAAP) device for advanced first aid is presented. Using swine as an animal model, two trials: 1) a large, curved cut in hindquarters area and 2) amputation of a front leg, were performed. Cold atmospheric-pressure air plasma effluent, which carries reactive oxygen species (ROS) atomic oxygen (OI), is applied for wound treatments. Swift hemostasis of the wounds by the CAAP treatment was demonstrated. The pressure applied by a finger on the cut arteries in trial 1 and the tourniquet applied in trial 2 could be removed immediately after the treatment and there was no re-bleed in both cases. CAAP hemostasis mechanism was explored via in-vitro tests. The tests on sodium citrate mixed blood-droplet samples show that 1) the heat delivered by the CAAP has no impact on the observed clot formation, 2) plasma effluent activates platelets to promote coagulation state and cascade, and 3) the degree of clotting increases with the total amount of applied OI by means of the CAAP effluent. It took only 16 s of the CAAP treatment to reach full clotting, which was considerably shortened from the natural clotting time of about 25 minutes. The tests on smeared blood samples show that the reduction of the platelet count and the increase of RBC count are proportional to the amount of applied OI. A plausible CAAP hemostasis mechanism is concluded from the in vitro test results and the animal model trials.

Any desired surface wettability of a plastic surface can be produced by changing the concentration of the plasma gas, which here is a mixture of oxygen and a compound which includes fluorine. In the plasma treatment, the use of a third electrode consisting of a metal mesh for ion trapping can significantly decrease the etching effect. The plastic surface wettability, given by the contact angle of a water drop, does not have any direct relationship with the surface roughness due to etching in this experiment.

Many useful processes for treating solid surfaces can be carried out by plasma methods. However, most previous work was done at low pressure, usually less than a few torr. For such low pressure processes, the vacuum apparatus requires great cost and is not suitable for the treatments of large scale substrates such as long film rolls. We previously reported that surface fluorination and thin film deposition could be carried out with the atmospheric pressure glow plasma (APG) process [1]. This approach can reduce apparatus costs and can also be applied to high vapor pressure substances such as gum, textiles and biomaterials. In this article, we will discuss the mechanism of stabilization of glow plasma at atmospheric pressure and report examples of applications of this technology.

Ion irradiation with various oxygen flow rates has been carried out to improve the wettability of polymethylmethacrylate (PMMA) to water and to enhance the adhesion between Al and the polymer. Ar+ ion and oxygen ion were irradiated on the polymer, and amounts of ions were changed from 5 × 1014 Ar+/cm2 to 5 × 1016 Ar+/cm2 by a broad ion beam source. Oxygen gas from 0 ml/min to 7 ml/min was flowed near the polymer surface during the ion irradiation, and the energy of ions was changed from 500 eV to 1500 eV. The wetting angle was reduced from 68° to 49° with the Ar+ ion irradiation only at 1 keV energy, to 43° with the oxygen ion irradiation, and dropped to 8° with Ar+ ion irradiation with flowing 4 ml/min oxygen gas near the polymer surface. Changes of wetting angle with oxygen gas and Ar+ ion irradiation were explained by a two-step chemical reaction among polymer matrix, energetic ions, and oxygen gas. The effects of Ar+ ion and oxygen ion irradiation were explained by considering formation of hydrophilic groups due to a reaction between irradiated polymer chain by energetic ion irradiation and blown oxygen gas, and enhanced adhesion between Al and PMMA was explained by the formation of electron acceptor groups in polymer and electron donors in metal, and by the chemical reaction in the interface between irradiated polymer surface and deposited metal.

A new surface modification technique, the so-called ion-assisted reaction (IAR), has been developed; such modification of polymer surfaces offers many industrial applications. The addition of new functional groups on polymer surfaces and permanent hydrophilic polymer surfaces (water contact angle below 30° and surface energy 60-70 mJ/m²) have been accomplished by IAR treatment. The formation of functional groups is significantly dependent on the flow rate of the reactive gas, the irradiating ion dose, and the ion beam energy. Improvements in wettability and surface energy are primarily attributed to the increase of polar characteristics due to the formation of functional groups such as (CO), (CO)O, (CO), etc. The characteristics of the IAR treatment have been reviewed, with outstanding results regarding the wettability and adhesion of various polymers such as PMMA, PC, PP, PS, PI, PVDF, and PTFE.

Adhesion, whether the bonding of polymers or the adhesion of coatings to polymer surfaces, is a recurring and difficult problem for all industries that use these materials as key components in their products. Designers must often select specially formulated and expensive polymeric materials to ensure satisfactory adhesion (albeit even these materials often require surface preparation). In some cases, entire design concepts must be abandoned due to the prohibitive cost of the required polymer or the failure of crucial bonds. Historically, surface treatments to improve adhesion of coatings to plastics consisted of mechanical abrasion, solvent wiping, solvent swell that was followed by acid or caustic etching, flame treatment, or corona surface treatment. Each of these treatments has limitations, thus providing a strong driving force for the development of alternative surface preparation methods. Many of the common methods mentioned are accompanied by safety and environmental risks, increased risk of part damage, and expensive pollution and disposal problems.

Polystyrene films of 100 nm thickness were modified using plasma immersion ion implantation (PIII) with argon ions of energy 20 keV and fluences in the range 2 × 10 ¹⁴-2 × 10 ¹⁶ ions cm ^-2. The structure and properties of the films were determined by ellipsometry and FTIR spectroscopy, as well as AFM, wetting angle measurements, profilometry and optical microscopy. The effects of oxidation, carbonization, etching and gel-formation were observed. The etching rate was found to decrease with PIII fluence. The rates of degradation with increasing fluence of the aromatic and aliphatic parts of the polystyrene macromolecule were found to be similar. Oxidation of the polystyrene film ceases at fluences greater than 10 ¹⁵ ions cm ^-2. The surface morphology of the film did not change with PIII fluence. Washing with toluene produced surface wrinkling for low fluences up to 10 ¹⁵ ions cm ^-2 while at high fluences the modified films were stable.

The chemical and morphological influences of SF6 and Ar plasmas on bisphenol-A-polycarbonate (PC) and the influence of plasma treatments on Al metallisation were investigated. The treatment of the sample, X-ray photoelectron spectroscopic (XPS) and scanning force microscopic (SFM) analyses were made in an ultrahigh vacuum (UHV) chamber without breaking the vacuum. Using SF6 for the etching process, a significant inclusion of fluorine (C-F, C-F2) takes place. After argon plasma treatment of the PC surface a reduction in the carboxylic carbon was observed in the C1s spectrum. Both kinds of plasma treatments reduce the double and single bonded oxygen. During the metallisation process on an Ar-plasma treated PC surface aluminum couples via oxygen to the aromatic carbon. Al-metallisation on the SF6 pre-etched surface leads to the formation of an Al-F interlayer. With the SFM, the roughening effects on the nm scale after the two plasma treatments is observable. On the virgin PC, Al layers can be seen as slightly bound clusters. On both plasma pre-treated PC surfaces the Al grows as a film.

In this work, air dielectric barrier discharge (DBD) operating at the line frequency (60 Hz) or at frequency of 17 kHz was used to improve the wetting properties of polypropylene (PP). The changes in the surface hydrophilicity were investigated by contact angle measurements. The plasma-induced chemical modifications of PP surface were studied by X-ray photoelectron spectroscopy (XPS) and Fourier-transformed infrared spectroscopy (FTIR). The polymer surface morphology and roughness before and after the DBD treatment were analyzed by atomic force microscopy (AFM). To compare the plasma treatment effect at different frequencies the variation of the contact angle is presented as a function of the deposited energy density. The results show that both DBD treatments leaded to formation of water-soluble low molecular weight oxidized material (LMWOM), which agglomerated into small mounts on the surface producing a complex globular structure. However, the 60 Hz DBD process produced higher amount of LMWOM on the PP surface comparing to the 17 kHz plasma treatment with the same energy dose. The hydrophilic LMWOM is weakly bounded to the surface and can be easily removed by polar solvents. After washing the DBD-treated samples in de-ionized water their surface roughness and oxygen content were reduced and the PP partially recovered its original wetting characteristics. This suggested that oxidation also occurred at deeper and more permanent levels of the PP samples. Comparing both DBD processes the 17 kHz treatment was found to be more efficient in introducing oxygen moieties on the surface and also in improving the PP wetting properties.

The theoretical analysis of electrostatic interactions and ion redistribution in the close vicinity of the three-phase contact line shows their important role in the Langmuir wetting process. To provide a sufficient rate for the ion transfer, which is intended to neutralize the interfacial charge, the concentration and potential distributions deviate from the equilibrium. As a consequence, during the deposition process the adhesion work, and hence the contact angle, are defined by the local ionic concentrations near the three-phase contact line. The concentration profiles and the electro-diffusion ion fluxes induced during the Langmuir wetting process are strongly dependent on the subphase composition and on the monolayer properties. The results of the analysis are in a good agreement with the experiments.

In this work, melt-spun polypropylene (PP) fibers were treated in an electric field of a corona discharge. The fibers were then characterized using the thermally stimulated current (TSC) spectroscopy. It has been shown that the electret state of corona-treated PP fibers is a result of the combination of Maxwell–Wagner polarization and charge trapping. Activation energies and relaxation times for these processes have been determined, and characteristics of trapping sites have been calculated. The electret state induced in PP fibers by the corona discharge treatment holds for a long time (several months). Our analysis of the effect of processing temperature and electric field intensity on the characteristics of the electret state in melt-spun PP fibers allows one to specify optimum technological regimes for industrial production of PP-based electret filter materials. © 2000 John Wiley & Sons, Inc. Adv Polym Techn 19: 312–316, 2000
https://onlinelibrary.wiley.com/doi/abs/10.1002/1098-2329%28200024%2919%3A4%3C312%3A%3AAID-ADV7%3E3.0.CO%3B2-X

A thermodynamic model is used to predict the adsorption of nonionic surfactants on latexes with different polarity. The model, which is based upon the Flory-Huggins theory of polymer solutions, predicts that the adsorption decreases as the polarity of the latex increases. It is predicted that adsorption should occur even when it is unfavorable to replace a surface-water contact with a surfacesurfactant contact. This is due to a lower number of unfavorable hydrocarbon-water contacts when the surfactant is adsorbed, compared to when it is free in solution. It is also predicted that it is in principle possible to determine the latex polarity or solubility parameter, from adsorption measurements, provided that a similar experiment is carried out on a latex with known polarity, or solubility parameter.

We present a new approach for the surface treatment of polymer films at atmospheric pressure. The DC glow discharge is generated by applying a high voltage between two electrodes which are placed in a channel with a high flux of air. The air flow removes charge carriers from the plasma zone which prevents the formation of sparks. In the almost homogeneous plasma a comparably high electrical power is converted forming a high concentration of active species. The flowing air transports them to the polymer surface. We report the results of the first experiments with this set-up. The influence of various process parameters on the discharge properties is shown. The resulting alterations in the surface structure of the polymers are characterised by XPS and contact angle geometry.

Corona treatment of films, mainly polypropylene (PP)-copolymers, was studied at commercial levels in a 2.7 kVA treater. The films were produced on a flat-film extruder with chill rolls. Degree of treatment was characterized by power of the generator divided by web speed and width of film (m Ws/cm²).

The effectiveness of the treatment was measured in terms of the polar and dispersion components of surface-energy, the peel adhesion of pressure sensitive tape (similar to ASTM Adhesion Ratio) and the peel adhesion of polyurethane adhesives.

The polar component of surface energy is a measure of the effectiveness of corona pretreatment. For a given degree of treatment, the polar surface energy component becomes greater as the film cooling rate increases (and the degree of crystallization falls).

A comparison of homopolymers and copolymers does, however, reveal that even where these have the same density or the same degree of crystallization one cannot count on them having equally-sized polar components.

Peel strengths of pressure-sensitive tapes and polyurethane-bonded patches confirm the influence of cooling conditions on wetting properties.

Many plastics have a poor tendency to bond to other materials because of their inherent inert chemical structure and thus require a pretreatment. Wet chemical methods are expensive because of the disposal of the waste liquids. In this study, the corona treatment (Ional process), the low-pressure plasma process, and the fluorination process were tested and compared with each other. The following plastics were tested: PP (polypropylene), PBT (polybutyleneterephthalate), PBT blends, and a high-temperature thermoplastic, PEEK (polyetheretherketone). In particular, the low-temperature plasma process results in excellent adhesion strength. In addition, we have shown that the stability of freshly plasma-treated surfaces could be maintained for time periods of at least several days.

Atomic-force microscopy was used to study structural chemical transformations on the surface of polyvinyl chloride films subjected to modification with compounds based on acrylic acid derivatives, with preliminary activation of the polymer surface with a corona discharge.