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.

A novel atmospheric pressure plasma jet, that is operated with air, is used for the pretreatmet of different polymers. The resulting adhesive bond strengths and the corresponding changes of the polymer substrate surface are studied. The plasma treatment induces chemical and topographical changes on the polymer surface. It is likely that both types of surface modification contribute to the adhesion improvement. Results for poly (ethylene terephthalate) indicate that surface chemical composition is more influential in adhesion enhancement than surface roughness.

Plasma web treatment is a common practice for promoting adhesion, wettability and other surface or interfacial properties in the conversion industry. While the objective of creating new surface functional groups is conceptually simple, it can be difficult to choose the most appropriate kind and configuration of plasma source, the most appropriate feed gas composition and the most appropriate operating pressure for a given application. Such difficulties arise from the variety of species that can be formed in the plasma and the variety of possible plasma-surface interactions that can occur. A brief review of the importance of various plasma parameters (eg, specific energy, species concentrations, and energy distributions) and an example relating nitrogen uptake in poly (ethylene-2, 6-naphthalate) to plasma diagnostic data in a low-radiofrequency capacitivelycoupled nitrogen plasma are presented. The importance of driving frequency and treatment configuration is discussed in detail. Uptake kinetics for samples treated at floating potential at low radiofrequency is compared with that for samples treated in the cathode sheath. Analysis of the treatment kinetics is based on a simple model of surface saturation. This approach can be used not only to compare practical treatment results as a function of process conditions, but also to compare different treatment techniques in a practical manner.

The use of gas and/or liquid-phase carbon dioxide (CO2) with atmospheric plasma discharge surface pretreatment technology can remove micron and submicron particulates and hydrocarbon-based contaminations on plastics and metals. The cleaning process is based upon the expansion of either liquid or gaseous carbon dioxide through an orifice. The paper provides an understanding of the basic removal mechanism and provides experimental evidence of remarkable adhesion improvements relative to a broad range of applications in electrical, medical, and automotive manufacturing communities.

We report on the preparation of amphiphilic diblock copolymers containing a hydrophilic segment, poly(acrylic acid)(PAA), and a polystyrene hydrophobic part. We analysed, by means of contact-angle measurements, how the hydrophilic segments usually bury themselves under the hydrophobic when exposed to air to reduce the surface free energy of the system. In contrast, in contact with water, the hydrophilic blocks have a tendency to segregate to the interface. We first describe the parameters that control the surface reconstruction when the environmental conditions are inversed from dry air to water vapour. Then, annealing time, temperature, composition and size of the diblock copolymers, and size of the matrix that influenced the surface migration process are the main parameters also considered. Finally, the density of the carboxylic functions placed at the surface was determined using the methylene blue method.

This chapter provides a general summary of the current state of knowledge of plasma modification of various natural cellulosic fibres. Much of the information reported here is taken from the references cited at the end of the chapter, which should be consulted for a more in-depth treatment. Several aspects of plasma modification of various natural cellulose fibres are thoroughly treated in a number of excellent works. [1, 2]

Growing demands on the functionality of technical textiles as well as on the environmental friendliness of finishing processes increase the interest in physically induced techniques for surface modification and coating of textiles. In general, after the application of water-based finishing systems, the textile needs to be dried. The removing of water is energy intensive and therefore expensive. In contrast to conventional wet finishing processes, a plasma treatment is a dry process. The textile stays dry and, accordingly, drying processes can be avoided and no waste water occurs. Plasma treatments represent, therefore, energy efficient and economic alternatives to classical textile finishing processes. Within plasma processes, a high reactive gaseous phase interacts with the surface of a substrate. In principle, all polymeric and natural fibres can be plasma treated. For many years, mainly low-pressure plasma processes have been developed for textile plasma treatment. However, the integration of these processes, which typically run at pressures between 0.1 and 1 mbar, into continuously and often fast-running textile production and finishing lines is complex or even impossible. In addition, due to the need for vacuum technology, low-pressure processes are expensive. The reasons why plasma processes at atmospheric pressure are advantageous for the textile industry are in detail: • The typical working width of textile machines is between 1.5 and 10 meters. Textile-suited plasma modules need to be scalable up to these dimensions, which is easier for atmospheric-pressure techniques.• Textiles have large specific surfaces compared to foils, piece goods or bulk solids. Even with strong pumps, the reduced pressure which is necessary for low pressure plasma will only be reached slowly due to the desorption of adsorbed gases.

Although the power of plasma surface engineering across vast areas of industrial manufacturing, from microelectronics to medical and from optics to packaging, is demonstrated daily, plasma in the textile industry has been cynically described as the technology where anything can happen... but never does. Research into the application of plasmas to textiles goes back to the 1960s but, despite the reporting of novel and potentially commercial effects, it is only in recent years that plasma processing systems have begun to emerge into textile manufacturing in the production of specialty/high value fabrics. It is instructive to look at major criteria for the introduction of new technology into the textile market and to assess plasma processing against such criteria. They can be separated into qualifiers (must be satisfied by the new technology as a minimum) and winners (motivate take-up of the new technology by the industry). Here are ‘qualifier’criteria for new textile technologies:

Plasma diagnostic tools are an essential element towards the proper understanding and development of technological plasmas. Knowledge of the particle densities and energies in the bulk and at boundaries, the electrical potentials and the spatial and temporal evolution of these parameters allow technologists to operate plasmas in the most efficient way and allow the intrinsic plasma processes to be tailored to suit a particular application. There are many different diagnostic tools that can be used, depending on the type of plasma under investigation and the specific information that is required. Here, we have chosen to highlight four techniques frequently used in both academia and industrial settings. The first of these is the interpretation of the driving current and voltage waveforms. These measurements do not affect the plasma and can yield useful information on the major processes in the discharge. The second is electrical probing which, by their nature, are intrusive, since their presence affects the plasma under investigation. Their use is usually confined to low-pressure and low-temperature plasmas in which the heat flux will not destroy the integrity of the probe. The third area is mass spectrometry, which is most often performed at the substrate or plasma boundaries and may in many cases not affect the plasma unduly. The fourth diagnostic method discussed, optical emission spectroscopy, is non-perturbing; however, interpretation of spectral response is often difficult in low-pressure plasmas where the species are not in local thermodynamic equilibrium.

Contact angle behavior of four relatively high surface tension ionic liquids (1,3-dimethylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium fluoroborate, and bis(hydroxyethyl)dimethylammonium methane sulfonate) was studied on seven hydrophobic surfaces and compared with water contact angle behavior. Smooth surfaces of various chemical compositions exhibit contact angles with ionic liquids that are lower than values obtained with water and that scale with liquid surface tension values. Contact angles of ionic liquids on rough perfluoroalkyl surfaces exhibit the highest contact angles reported for liquids other than water and are indistinguishable from those of water and not dependent on liquid surface tension. Superhydrophobic methylsilicone surfaces that exhibit high water contact angles and low hysteresis exhibit very low receding contact angles with ionic liquid probe fluids and high hysteresis. The potential for ionic liquids as probe fluids is argued because of their variable and controllable surface tension, interface charge density, interface dipole density, as well as their variable and controllable cation/anion structure and molecular volume.

Surface properties of a Melinex 800 PET polymer material modified by an atmospheric-pressure air dielectric barrier discharge (DBD) have been studied using X-ray photoelectron microscopy (XPS) and contact angle measurement. The results show that the material surface treated by the DBD was modified significantly in chemical composition, with the highly oxidised carbon species increasing as the surface processing proceeds. The surface hydrophilicity was dramatically improved after the treatment, with the surface contact angle reduced from 81.8° for the as-supplied sample to lower than 50° after treatment. Post-treatment recovery effect is found after the treated samples were stored in air for a long period of time, with the ultimate contact angles, as measured, being stabilised in the range 58–69° after the storage, varying with the DBD-treatment power density. A great amount of the C–O type bonding formed during the DBD treatment was found to be converted into the CO type during post-treatment storage. A possible mechanism for this bond conversion has been suggested.

Combined surface treatments using plasma fluorination and surface roughening were applied to investigate whether they could increase the peel property of PET beyond the value needed for use as a release coating of pressure-sensitive adhesive tapes. The peel strength of PET treated with CF₄/He APG plasmas decreased to approximately 100 N · m⁻¹, but not quite to the ideal value of PTFE, 20 N · m⁻¹. We also prepared PET with a rough surface (matte PET) to examine the effect of surface roughening. The matte PET peel strengths were decreased by plasma fluorination; the roughest matte PET showed even lower peel strength than PTFE. We conclude that the combined treatments could be effective in the formation of a surface with high peel property on PET.

This study describes experiments to quantify polymer surface energy changes after exposure to atmospheric plasma. Atmospheric plasma treatment permits surface functionalization at near-ambient temperatures. Polyethylene and polystyrene are treated with an atmospheric plasma unit. The increased surface energy and improved wetting characteristics lead to a significant adhesion improvement with adhesives that cannot be used without surface treatment.

The effect of ultraviolet (UV) radiation in the presence of ozone as a surface treatment for polycarbonate is examined in regards to changes in the wettability, adhesion, and surface mechanical properties. Standalone, 175-µm-thick films of a commercially available polycarbonate were exposed to UV radiation from sources of different power with various treatment times in the presence of supplemental ozone. Significant decreases in the water contact angle were observed after exposure to UV radiation in the presence of ozone. After several variations in the experimental setup, it was determined that the change in water contact angle is a function of the UV irradiance and the work of adhesion follows a master curve versus UV irradiance. Nanoindentation experiments revealed that the modulus of the top 500 nm of the surface is increased following UV exposure, attributable to surface cross-linking. Adhesion tests to the surface (conducted by a pneumatic adhesion tensile test instrument) showed little change as a function of UV exposure. Analysis of adhesion test failure surfaces with X-ray Photoelectron Spectroscopy (XPS) showed the locus of bond failure lay within the bulk polycarbonate and the measured bond strength is limited by the bulk properties of the polycarbonate and/or the creation of a weak boundary layer within the polymer.

Polypropylene (PP) films have been widely used in many industrial areas, such as for protective overcoats and food packaging. However, PP film’s hydrophobic surface properties induce poor wettability and adhesion; these properties have restrained the application of these films. Many surface modification techniques like wet-chemical treatment, UV irradiation, and plasma (including the atmospheric-pressure plasma, APP) treatment have been applied to films to enhance their hydrophilic properties. Among these technologies, APP treatment has attracted much attention due to its dry process, low vacuum equipment cost, and high productivity. In this study, the influence of process parameters would be the reactive gas ratio of plasma. To enhance its surface characteristics, treatment of PP film’s surface by APP was investigated. The XPS, OES, contact angle analyzer, SEM and AFM were used to examine the effect of process variables on film surface characteristics. It was found that Ar plasma mixing with oxygen has a better lasting aging effect. Moreover, the roughness of films is slightly changed after treatment. Through XPS analysis, we observed that the O/C ratio of PP decreases with an increased exposure time in air. Finally, the relationship among the aging time, surface energy, and roughness of the film was also investigated.