Adhesion Of Polymer Films Research Articles

Strengthening adhesion of polycarbazole films on ITO surface by covalent electrografting of monomer

Strong adhesion of a functional polymer coating to a solid support is a key requirement to achieve its robustness and high performance in different application areas. Herein, a novel carbazole derivative, 9-methyl-9H-carbazole-3,6-diamine (m-Cz-diamine), is synthesized and covalently grafted onto an ITO surface through the diazonium electroreduction method. The functionalization of the ITO surface is confirmed by XPS spectroscopy, water contact angle measurements and cyclic voltammetry analysis, revealing the covalent anchoring of an organic film (m-Cz-ITO). The functionalized ITO surface is then studied for oxidative electropolymerization of m-Cz-diamine and carbazole, showing clear advantages over a bare ITO substrate in terms of polymer film adhesion. The polymer films electrodeposited onto an electrografted ITO surface demonstrate very strong adhesion, as they do not delaminate, either by a scotch tape pulling, storing in air, or immersing under water for two months. On the other hand, the polymer films grown on a bare ITO substrate peel off easily in all the aforementioned stability tests. Therefore, electrografting an organic film onto the ITO surface clearly improves the adhesion of the polymer films on top of it. Moreover, it is interesting to note that the physicochemical properties of the polymer films deposited on the functionalized ITO substrate remain unchanged.

Surface analysis of polymer films for wettability and ink adhesion

AbstractThe interaction between inks and substrates is critical during printing. Adhesion of the ink film is determined by the reciprocal interactions of polar and nonpolar (dispersive) components between polymer films and inks. The greater the similarity between the polar and dispersive components of inks, coating and substrates, the better the wetting and adhesion on the surface of printing substrate. Various liquid materials in printing such as inks, varnishes, lacquers, and adhesives contain high ratios of water. The highly polar nature of water makes the interaction of these materials unsuitable with predominantly disperse polymer surfaces. Some films with polyolefin structure, especially polypropylene, and polyethylene, are nonpolar and cannot form strong bonds with ink, varnish, or lacquer coatings due to their chemical structure. Increasing surface energy components overcomes the poor wetting and adhesion on polymer surfaces. In this review, the topics of water contact angle measurement and determination of surface energy, surface tension, and using sessile drop method for the wettability and ink adhesion of polymer films are surveyed. Information on structural and chemical processes was given that assists in obtaining wettable film surfaces. Recommendations were made for good adhesion and printability based on surface treatment methods and ink modification.

Influence of Copolyester Composition on Adhesion to Soda-Lime Glass via Molecular Dynamics Simulations.

Copolyesters are a subset of polymers that have the desirable properties of strength and clarity while retaining chemical resistance, and are thus potential candidates for enhancing the impact resistance of soda-lime glass. Adhesion between the polymer and the glass relates to the impact performance of the system, as well as the longevity of the bond between the polymer and the glass under various conditions. Modifying the types of diols and diacids present in the copolyester provides a method for fine-tuning the physical properties of the polymer. In this study, we used molecular dynamics (MD) simulations to examine the influence of the chemical composition of the polymers on adhesion of polymer film laminates to two soda-lime glass surfaces, one tin-rich and one oxygen-rich. By calculating properties such as adhesion energies and contact angles, these results provide insights into how the polymer-glass interaction is impacted by the polymer composition, temperature, and other factors such as the presence of free volume or pi stacking. These results can be used to optimize the adhesion of copolyester films to glass surfaces.

Electrochemical and morphological characterisation of polyphenazine films on copper

The morphology of films of the phenazine polymers poly(neutral red) (PNR), poly(brilliant cresyl blue) (PBCB), poly(Nile blue A) (PNB) and poly(safranine T) (PST), formed by potential cycling electropolymerisation on copper electrodes, in order to reduce the corrosion rate of copper, has been examined by scanning electron microscopy (SEM). The copper surface was initially partially passivated in sodium oxalate, hydrogen carbonate or salicylate solution, in order to inhibit copper dissolution at potentials where phenazine monomer oxidation occurs, and to induce better polymer film adhesion. SEM images were also taken of partially passivated copper in order to throw light on the different morphology and anti-corrosive behaviour of the polyphenazine films. Analysis of the morphology of the polymer-coated copper with best anti-corrosive behaviour after 72h immersion in 0.1M KCl, Cu/hydrogen carbonate/PNB, showed that the surface is completely covered by closely packed crystals. By contrast, images of PST films on copper partially passivated in oxalate solution, that had the least protective behaviour, showed large amounts of insoluble corrosion products after only 4h immersion in 0.1M KCl.

Correlating Interfacial Moisture Content and Adhesive Fracture Energy of Polymer Coatings on Different Surfaces

The adhesion of polymer film of PMMA to different surfaces was measured using the shaft‐loaded blister test. The exposure of the films to saturated water vapor generally leads to a decrease in adhesive strength. The adhesion loss was directly related to the moisture accumulation at the polymer/substrate interface as measured using neutron reflectivity.

The Role of Dielectric Barrier Discharge Atmosphere and Physics on Polypropylene Surface Treatment

Dielectric barrier discharge (DBD) is the discharge involved in corona treatment, widely used in industry to increase the wettability or the adhesion of polymer films or fibers. Usually DBD's are filamentary discharges but recently a homogeneous glow DBD has been obtained. The aim of this paper is to compare polypropylene surface transformations realized with filamentary and glow DBD in different atmospheres (He, N2, N2 + O2 mixtures) and to determine the relative influence of both the discharge regime and the gas nature, on the polypropylene surface transformations. From wettability and XPS results it is shown that the discharge regime can have a significant effect on the surface transformations, because it changes both the ratio of electrons to gas metastables, and the space distribution of the plasma active species. This last parameter is important at atmospheric pressure because the mean free paths are short (∼μm). These two points explain why in He, polypropylene wettability increase is greater by a glow DBD than by a filamentary DBD. In N2, no significant effect of the discharge regime is observed because electrons and metastables lead to the same active species throughout the gas bulk. The specificity of a DBD in N2 atmosphere compared to an atmosphere containing oxygen is that it allows very extensive surface transformations and a greater increase of the polypropylene surface wettability. Indeed, even in low concentration and independently of the discharge regime, when O2 is present in the plasma gas, it controls the surface chemistry and degradation occurs.

Improved latex film-glass adhesion under wet environments by using an aluminum polyphosphate filler

—Non-crystalline aluminum polyphosphate (A1PP) was added as a filler to poly(vinyl acetate) latex and the resulting dispersion was used both as a glass coating and as a glass-to-glass adhesive. Latex-coated glass samples were subjected to a grid adhesion test following the ASTM D 3359 standard, in which the samples are immersed in water. A1PP improves the latex polymer film adhesion to glass, as evidenced by coating film and adhesive joint stabilities. This is explained in terms of the formation of Al3+ ion bridges between the polymer-polyphosphate bicontinuous composite film and the glass surface.

Electrochemical impedance study of the degradation of organic-coated copper

Electrochemical impedance spectroscopy (EIS) was used to study the corrosion behavior of organic-coated copper plate. The organic coatings of commercial lacquer or epoxy Epon resin 828 (Shell Co.) were evaluated in 0.5 M sodium chloride solutions. It was found that the coating was saturated with water after a short period of time and a rapid increase of coating capacitance and decrease of resistance were observed. The penetration of water molecules and electrolytes within the organic coating proceeds in three steps. Firstly, water diffuses into the coating and saturates the free volume of the coating, causing a rapid rise of capacitance. Secondly, the electrolytes penetrate within the voids into the metal–coating interface and the corrosion of metal intensifies; the coating resistance R p and electrode charge transfer resistance R ct decrease gradually during this period. The last period of time corresponds to the constant R p and R ct plateaus followed by decreases of these resistances due to a loss of adhesion of polymer film on the copper substrate. The EIS procedure developed in the study proved to be useful to characterize the degradation behavior of the copper–coating system.

Adhesion of polymer films to oxidized silicon and its effect on performance of a conductometric pH sensor

The use of a silane coupling agent, γ-methacryloxypropyl trimethoxysilane (γ-MPS), to promote adhesion of photolithographically patterned polymer hydrogels to oxidized silicon wafers and conductometric sensors has been examined. Poly-(hydroxyethyl methacrylate-co-dimethylamino ethylmethacrylate) (HEMA/DMA) polymer hydrogels are photolithographically patterned on wafers treated with γ-MPS. The wafers are immersed in buffered potassium chloride solutions of differing pH and subjected to a peel test of adhesion. Hydrogels tested in a high-pH (9.0) medium show considerably poorer adhesion than ones tested in lower-pH media (6.0 and 7.4). Hydrogels tested at elevated temperature (40°C) show comparable adhesion to those tested at room temperature (23°C). Adhesion of hydrogels that are cycled between pH 9.0 and a dry environment exhibit better adhesion than ones cycled between pH 9.0 and 6.0. This indicates that there is reformation of siloxane bonds between the polymer and the substrate. Since loss of siloxane bonds is the major determinant of sensor failure, it is possible to regenerate the performance of failed sensors by drying in a vacuum oven. These findings have implications in the design and construction of microfabricated sensors that utilize polymer hydrogel sensing layers. In recognizing the pH sensitivity of adhesion, it is possible to prevent sensor failure by restricting the pH of the testing environment to values that favor the maintenance of the siloxane bond.

Electropolymerization of pyrrole on Fe and Pt electrodes in methanol and acetonitrile. Evidence of interfacial layers resulting from accumulation and decomposition of the supporting electrolyte

AbstractThe partial decomposition of PF6− during pyrrole electropolymerization in methanol and acetonitrile on Fe and Pt electrodes is demonstrated using XPS analysis. A complex mixture of PF6−, fluorides of phosphorus and metal oxides is shown to exist in the interfacial region, probably resulting in a weak cohesive layer unfavourable to the adhesion of polymer films.

Enhancement of polymer film adhesion using acid-base interactions determined by contact angle measurements

Quantitative correlations among surface chemical composition, acid-base thermodynamics, adhesion strength, and locus-of-failure are demonstrated. Four types of functional Teflon surfaces were prepared: two acidic (containing hydroxyl and carboxyl groups), and two basic (containing acetyl and dinitrobenzoate groups). X-Ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopy were used to characterize the molecular structure of the surface region. Contact angle adsorption isotherms were determined using phenol as an acidic probe and tetrahydrofuran (THF) as a basic probe. The carboxylated surface had a higher molar ▵Hab with basic THF than the hydroxylated surface, and neither surface had any interaction with the acidic phenol probe. The acetylated surface behaved as a base, interacting with phenol but not with THF, while the dinitrobenzoyl surface had both acidic and basic character. Adhesion tests were carried out in the 180° peel mode using post-chlorinated poly...

Polylmide Adhesion as a Function of Substrate Structure

AbstractWe have investigated the effect of different inorganic substrates on the adhesion of polymer films. We have used crystalline surfaces in an effort to “map” the adhesive interactions that take place through the interface between substrate and polyimide (-arnic acid). Significant differences were found in the adhesion of polyimide films (as measured by peel tests) on substrates varying only in crystalline orientation. Detailed analytical investigations are reported of the interfaces of these substrates after peeling of the film, using angular dependent ESCA. A correlation was found between the chemical nature of the substrate and the adhesion quality. This correlation involves the crystalline matrix of the substrate surface.

Adhesion model and experimental verification for polymer—SiO 2 system

The adhesion of polymer films to the SiO 2 surface is strongly influenced by ambient conditions. In a dry environment, polymer films adhere to SiO 2 surfaces through London dispersion force, whereas in liquid media the effect of liquid penetration must also be considered. These interactions are evaluated in terms of the surface free energies and wettability of SiO 2, and polymer films. A series of experiments has been carried out utilizing surface conversion techniques to alter the surface of thin SiO 2 films. Using these experiments, a model has been developed to describe the organic polymer—SiO 2 adhesion.

Cyclic voltammetry for the study of polymer film adhesion to platinum neurological electrodes

Many epoxy and polymeric coatings, with a broad spectrum of bulk and surface properties, are available for microelectrode insulators in neurophysiology. One of the premier properties of a biomaterial must be its ability to adhere to the underlying substrate. The technique of cyclic voltammetry has been applied to neurological electrodes to compare the adhesion of various insulating films. We found that this technique was advantageous over conventional ones (i.e. pull tests) in that we could observe the synergistic effects of water, ions, and electric fields.