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.

Surface and interface characterization of polymeric materials has not enjoyed the multi-technique approach which typifies other types of materials. X-ray photoelectron spectroscopy (XPS) has dominated, despite several major disadvantages. New approaches are discussed which either improve XPS (particularly derivatization techniques) or utilize ‘static’ secondary ion mass spectrometry (SIMS) to overcome these limitations, with examples of their application in materials problem solving.

Titanium films, 1 μm thick were electron‐beam evaporated onto polyethylene (PE) that had been pretreated in situ by 2 keV Ar⁺ bombardment. A measure of the film adhesion was obtained by measuring the pull strength required to remove the Ti films. A strong dependence of the adhesion on the ion dose was found. The pull strength had a maximum of approximately 20 MPa after a dose of 6×10¹⁴ ions/cm² but decreased for higher ion doses. Without any ion bombardment prior to deposition, the adhesion was very poor with a pull strength of approximately 2 MPa. XPS analysis was used to examine the effect of the ion bombardment on the chemistry of the PE substrate and the Ti/PE interface. Untreated PE samples were contaminated with surface impurities and probably also with low molecular weight hydrocarbons. As the adhesion is maximized, most of the impurities are removed by the ion bombardment. The strong adhesion is suggested to be due to formation of a carbidelike Ti–C interfacial layer, detected by XPS.

Aluminium and titanium surfaces have been treated by corona discharge in air and gave bonds of strength similar to those obtained by conventional chemical treatment.

Contact angle measurements have been carried out on various solid substrates using water-propanol mixtures and α-bromonaphthalene as wetting liquids. These substrates were: polytetrafluorethylene, Parafilm, polyethylene, polyurethane, polystyrene, polymethylmethacrylate, fluorapatite, and hydroxyapatite. The dispersion and the polar components of the surface free energy, γ_s^d and γ_s^p have been calculated from the geometric mean equation. Two approaches have been considered: (1) neglecting the spreading pressure π_e and (2) taking π_e into account (Dann's method). The results show that both approaches actually yield the same results for the surface free energy, γ_s, if a proper interpretation of the approaches is considered. All data indicate, that approach (1) gives γ_s values determined on the adsorbed liquid layer, whereas in approach (2) the free energies of the bare solid surfaces are found.

The surface tension and the dispersion and polar components of the surface tension for solids and liquids were estimated by contact angle measurement in order to apply these concepts to a detergency study. Two approximation methods, the extended Fowkes' equation and Wu's equation, were adopted for the calculations. Among the twelve experimental liquid pairs, methylene iodide/water and tricresyl phosphate/water gave values for paraffin, polyethylene, and polystyrene close to the average for the twelve pairs. Values for cellulost acetate and cellophane were there fore obtained using these two pairs. The results showed that the dispersion force component becomes larger with increasing degree of acetylation, while the polar force component becomes smaller.

Examples of surface characterization using cohesive energy parameters and surface energy parameters are given. In general the two approaches yield essentially equivalent results. The predictive ability of the cohesive energy approach suggests its use where directed modification of surface properties is desired.

The surface contact angle of glycerol and of water on polystyrene (PS) films has been found to depend on the extent of uniaxial draw for atactic PS. The contact angle depends on direction for the smooth films of PS drawn by solid state coextrusion. Results as a function of draw ratio to values over 4 on these noncrystalline PS samples, M_w = 6 × 10⁵, have also been interrelated with other measures of orientation such as the anisotropy of surface and bulk properties measured, respectively, by dichroic reflectance infrared spectroscopy and by birefringence.

The effects of the modification of polystyrene (PS), polyethylene (PE), poly(vinyl chloride) (PVC), silicone rubber (SR), and fluorinated ethylene propylene (FEP) copolymer by radio frequency glow discharge in a helium environment were presented in part I. The hydrated polymer surfaces were characterized by XPS, SEM, visual microscopy, and by contact angle measurements. In general, exposure of the polymers to RFGD produced an oxidized hydrophilic surface, yet the roughness of the surface was unaltered by the relatively mild plasma conditions used. In this article, the frictional behavior of oxidized and unoxidized SR, PE, and FEP in distilled water, isotonic saline, and blood plasma environments is examined experimentally. The results are discussed in relation to the properties generally believed to affect frictional phenomena and to the surface properties as determined in part I. Results indicate that RFGD-treated SR generates less friction than untreated SR when dragged across all untreated and treated polymer surfaces, whether the medium is distilled water or an isotonic saline solution. Friction is consistently lower in a blood plasma medium between all surfaces investigated, most probably because of the presence of adsorbed proteins at the polymer interfaces.

The previously observed, but unexplained, deleterious effect of high relative humidity on the efficiency of electrical (‘corona’) discharge treatment for rendering polypropylene film printable has been re-examined. The effect of film temperature during treatment has also been studied. A consistent explanation of both effects based on the degree of surface coverage by physically adsorbed water is put forward, supported by X-ray photoelectron spectroscopy analysis of treated film surfaces.

In investigating the effect of the surface energetics of substrate materials on the adhesion characteristics of poly(p-xylylene) and poly(chloro-p-xylylene) by the “Scotch Tape” method, it was found that if the substrates had not been preconditioned (treated with argon or a methane plasma), the adhesion was poor. The characteristics of water resistant adhesion that were observed when coated substrates were boiled in 0.9% sodium chloride solution were found to vary from excellent (when the polymer did not peel from the substrate after three cycles of 8 hours of boiling and 16 hours at room temperature) to poor (when the polymer peeled off almost immediately). It was noticed that water resistant adhesion depends on the hydrophobicity of the substrate material (the greater the hydrophobicity, the greater the adhesion) and is not related to the dry adhesive strength of poly(p-xylylene). The oxygen glow discharge treatment of the substrates decreased both the dry and wet adhesive strength of the polymer. The effect of the argon glow discharge treatment depended on the surface energetics of the substrate, and the methane glow discharge treatment increased both the dry and wet adhesive strength of the polymer. These preconditioning processes are discussed in terms of the sputtering of the material from the wall of the reactor in contact with the plasma and the deposition of the plasma polymer of the sputtered material on the substrate surface.

A technique has been developed for estimating the hydrogen bonding and London dispersion force components of liquid surface tension and solid surface free energy levels. The technique relies on (a) measuring contact angles generated by sessile drops of liquids on solids and (b) performing calculations based on theories of thermodynamic wetting of solids by liquids. The technique is used to estimate interfacial force components of certain liquids and papers typical of those used in xerographic processing.

Specific reactions for the derivatization of oxygen-containing functional groups in polymer surfaces have been developed in order to improve the precision of analysis by X-ray photoelectron spectroscopy (xps). These have been used to probe the chemical composition of low density polyethylene (ldpe) surface-modified by electrical discharge treatment. Simultaneously the effect of derivatizing particular groups on the auto-adhesive behaviour of these surfaces has been examined. Two independent specific interaction mechanisms have been identified.

The effect and interrelationship between primary (segmental backbone) and secondary (side chain) molecular motions on thrombogenesis, independent of morphological order/disorder, crystallinity, and/or associated water is elucidated using an amorphous hydrophobic polymer of poly-[(trifluoroethoxy) (fluoroalkoxy)phosphazene], PNF. The results indicate that thrombogenesis for an amorphous hydrophobic polymer is sensitive and dependent on the degrees and types of primary and secondary molecular motions at the polymer interface.

The above results are intended to be suggestive rather than definitive. Nevertheless, they strongly support the premise that a cross-fertilization of both concepts and experimental data from the apparently unrelated fields of Lewis acid-base chemistry and adhesion theory can lead to potentially valuable results for both fields, emphasizing again the value of using a generalized acid-base vocabulary in describing the phenomena of chemistry, whatever one's area of specialization.