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2046. Schreiber, H.P., and M.D. Croucher, “Surface characteristics of solvent-cast polymers,” J. Applied Polymer Science, 25, 1961-1968, (Sep 1980).

Films of poly(methyl methacrylate) (PMMA), polystyrene, and a styrene/acrylic terpolymer have been cast from solutions of varying thermodynamic quality and the film properties studied by inverse gas chromatography and by critical surface tension measurements. Surface properties of the non-polar polystyrene were independent of solvent medium, but significant variations in these properties were observed in the case of PMMA and the terpolymer. Solvent balance also appeared to affect the bulk properties of the latter films, as judged by the penetration rates of interacting liquids. The observations indicate the feasibility of controlling film properties of the solid by the appropriate selection of solution media; a time-dependent variation in solid properties is to be expected, however, as the film structure attains an equilibrium state.

2055. Kim, J.H., D.S. Shin, M.H. Han, O.W. Kwon, H.K. Lee, et al, “Surface free energy analysis of poly(vinyl alcohol) films having various molecular parameters,” J. Applied Polymer Science, 105, 424-428, (Jul 2007).

The molecular parameters of poly(vinyl alcohol) have enormous effects on its physical and chemical properties. Therefore, the surface characteristics of poly(vinyl alcohol) films are also determined by the molecular parameters. In this study, the dependence of the surface free energy on the molecular weight, degree of saponification, and stereoregularity of poly(vinyl alcohol) films has been evaluated with contact-angle measurements. The surface free energy of poly(vinyl alcohol) films increases with decreases in the syndiotactic dyad content, molecular weight, and degree of saponification. The polar component of the surface energy is not affected by the deviation of the molecular weight and degree of saponification very much. However, it decreases with increases in the syndiotactic dyad content and ranges from 11.64 to 4.35 dyn/cm.
© 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

2061. Goldblatt, R.D., L.M. Ferreiro, S.L. Nunes, et al, “Characterization of water vapor plasma-modified polyimide,” J. Applied Polymer Science, 46, 2189-2202, (Dec 1992).

To enhance polyimide-to-polyimide adhesion, we have investigated the effect of surface modification in water vapor plasma. The use of a water vapor plasma to treat a fully cured polyimide (PMDA–ODA) surface before subsequent layers of polyimide are applied results in dramatically enhanced interfacial adhesion. The polyimide-to-polyimide interfacial adhesion strength attained following water vapor plasma treatment exceeds the cohesive strength of the applied polyimide layer. The effect of surface modification in water vapor plasma on metal-to-polyimide adhesion has also been investigated. The use of a water vapor plasma to treat a fully cured polyimide (PMDA–ODA) surface prior to metallization results in increased metal-to-polymer interfacial adhesion. A study of both electroless and vacuum-deposited metal was conducted. The use of contact-angle measurements, peel tests, Fourier transform infrared spectroscopy, optical emission spectroscopy, nuclear forward scattering, and X-ray photoelectron spectroscopy has led us to a preliminary understanding of the resulting surface modification and the subsequent effect of adhesion promotion. © 1992 John Wiley & Sons, Inc.

2069. Han, S., W.-K. Choi, K.H. Yoon, S.-K. Koh, “Surface reaction on polyvinylidenefluoride (PVDF) irradiated by low energy ion beam in reactive gas environment,” J. Applied Polymer Science, 72, 41-47, (1999).

Polyvinylidenefluoride (PVDF) was irradiated by a keV Ar+ ion in O2 environment for improving adhesion between PVDF and Pt, and reaction between PVDF and the ion beam has been investigated by X-ray photoelectron spectroscopy (XPS). The adhesion test between Pt and the modified PVDF was carried out by boiling test, in which the specimens were kept in boiling water for 4 h. Two failure modes (buckling up due to weak adhesion and crack formation due to strong adhesion) of Pt films have been observed in the system. Contact angle of PVDF was reduced to 31 from 75° by the irradiation of 1 × 1015 Ar+ ions/cm2 with oxygen flow rate of 8 sccm. The surface of the irradiated PVDF became more rough as ion dose increased. The improved adhesion mechanism and identification of newly formed chemical species have been confirmed by Carbon 1s and Fluorine 1s X-ray photoelectron core-level spectra. The main reaction occurred at the irradiated PVDF surface is an ion-beam-induced oxidation accompanied with preferential sputtering of fluorine. Newly formed chemical species at interface are regarded as ester and carboxyl groups. Adhesion of the Pt–PVDF interface was improved by ion irradiation in O2 environment. This improvement is originated from the presence of carbon—oxygen bonds on the irradiated PVDF surface. Comparison of failure modes on the irradiated PVDF at various conditions after the boiling test shows that adhesion of Pt film is largely affected by the product of ion-assisted reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 41–47, 1999;2-J

2098. Ulbricht, M., and G. Belfort, “Surface modification of ultrafiltration membranes by low temperature plasma I: Treatment of polyacrylonitrile,” J. Applied Polymer Science, 56, 325-343, (Apr 1995).

Excitation with low temperature helium or helium/water plasma and subsequent exposure to air of polyacrylonitrile (PAN) ultrafiltration membranes was used to hydrophilize the surface of these materials. We analyzed the effectiveness of this approach as a function of plasma operating variables including gas phase composition, plasma power, treatment time, and system pressure. Following the changes in physical and chemical composition of the PAN surface resulting from these modifications was a major aspect of this work. Techniques such as the captive bubble contact angle method, ellipsometry, ESCA, and FTIR-ATR were all used. In addition, the formation and lifetime of peroxides during these processes were determined. At low powers (≤ 25 W) and short treatment periods (≤ 30 s), the main chemical conversion of PAN surfaces was simultaneous hydrophilization and stabilization via PAN cyclization. Relatively small water permeability changes were observed as a result of such treatment. © 1995 John Wiley & Sons, Inc.

2108. Yasuda, T., M. Gazicki, and H. Yasuda, “Effects of glow discharges on fibers and fabrics,” J. Applied Polymer Science, 38, 201-214, (1984).

2109. Matsuzawa, Y., and H. Yasuda, “Semicontinuous plasma polymerization coating onto the inside surface of plastic tubing,” J. Applied Polymer Science, 38, 65-74, (1984).

A semicontinuous, if capacitively coupled plasma polymerization apparatus was designed and constructed to coat the internal surface of a small-diameter plastic tubing. The glow zone was restricted to a small area to obtain a uniform coating of plasma polymer over the entire length of tubing (13 m long). It was found that a uniform coating can be achieved by maintaining the glow discharge parameters and velocity of moving substrate. In such a reactor, it was found that the deposition rates obtained for plasma polymers of tetrafluoroethylene, hexafluoroethane, and hexafluoroethane/hydrogen were very high compared with those polymerized in a conventional plasma polymerization apparatus. Special attention was needed to avoid deposition of an excessively thick coating, which was found to damage the barrier characteristics of the coating

2110. Bottin, M.F., H.P. Schreiber, J. Klemberg-Sapieha, and M.R. Wertheimer, “Modification of paper surface properties by microwave plasmas,” J. Applied Polymer Science, 38, 193-200, (1984).

A large-volume microwave plasma (LMP) apparatus has been used to polymerize organosilicone and styrene vapors onto paper substrates. Polymerization rates were established in the active glow of the plasma and in the dark, downstream volume of the reactor. Rates decrease from about 70 Ä/s in the former to about 1 Ä/s in the latter space. Surface modifications of paper substrates were studied by measurements of contact angles, of resistivity, and of charge retention properties. Plasmapolymer layers increased water contact angles from about 45 for control paper samples to> 110 for plasma-treated specimens. Resistivity was increased by up to four orders of magnitude, and the charge retention of coated papers was increased significantly. Controlled variations of the environment into which materials were placed immediately after plasma polymerization led to changes in the property balance of paper, confirming that plasma-polymer surfaces remain in active states for some time following quenching of the plasma.

2269. Deshmukh, R.R., and A.R. Shetty, “Comparison of surface energies using various approaches and their suitability,” J. Applied Polymer Science, 107, 3707-3717, (Mar 2008).

The surface chemistry and surface energies of materials are important to performance of many products and processes—sometimes in as yet unrecognized ways. This article has been written for the researchers who wish to calculate solid surface energy (SE) from contact angle data. In this article, we describe various methods of calculations and their assumptions. The theoretical and experimental approaches for understanding the solid surface free energy using various methods are discussed in this article. Researchers concerned with many fields such as printing, dyeing, coating, adhesion, pharmaceuticals, composite materials, textiles, polymers, and ceramics should have interest in this topic. SE calculated by various methods for polyethylene surface treated in air plasma is discussed. Using contact angle data, the values of surface roughness using Wenzels equation, have been obtained and correlated to surface roughness calculated from AFM data.
© 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

2327. Hall, J.R., C.A.L. Westerdahl, M.J. Bodnar, and D.W. Levi, “Effect of activated gas plasma treatment time on adhesive bondability of polymers,” J. Applied Polymer Science, 16, 1465-1477, (Jun 1972).

The bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low-density polyethylene, high-density polyethylene (two types), poly(4-methyl-1-pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength-versus-exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.

2426. Urbaniak-Domagala, W., “Pretreatment of polypropylene films for following technological processes, II: The use of low temperature plasma method,” J. Applied Polymer Science, 122, 2529-2541, (2011).

The surface of polypropylene (PP) films was activated by RF plasma method with the use different gases: argon, air, water vapor, and acetic acid vapor. Plasma was diagnosed based on spectra emitted by gas plasma using the method of optical emission spectroscopy. The effectiveness of these processing gases during plasma treatment was analyzed. The effects of PP activation were assessed with the use of IR-ATR absorption spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and the analysis of the surface free energy components based on liquid contact angle. The activation of PP surface by plasma treatment resulted in the increased energy of PP surface layer to the extent being dependent on the type of processing gases and in the formation of new chemical groups on it. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

2517. Inagaki, N., S. Tasaka, K. Narushima, and H. Kobayashi, “Surface modification of PET films by pulsed argon plasma,” J. Applied Polymer Science, 85, 2845-2852, (Sep 2002).

The rf power was modulated (discharge on-time of 10 μs and discharge off-time of 50–500 μs), for pulsed argon (Ar) and oxygen (O2) plasmas used to irradiate PET film surfaces to modify the film surfaces. From data regarding the contact angle for the modified PET film surfaces and chemical analyses with XPS, effects of the rf power modulation on the surface modification are discussed. The pulsed Ar and O2 plasmas are effective in modification of the PET film surface. There is no difference in the contact angle between the pulsed plasma and the continuous plasma. Furthermore, the pulsed Ar plasma is advantageous in formation of hydroxyl groups on the PET film surfaces. The rf power modulation has a possibility to modify into peculiar surfaces. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2845–2852, 2002

2518. Inagaki, N., S. Tasaka, and S. Shimada, “Comparative studies on surface modification of poly(ethylene terephthalate) by remote and direct argon plasmas,” J. Applied Polymer Science, 79, 808-815, (Jan 2001).

Surface modification of poly(ethylene terephthalate) (PET) film by an argon (Ar) plasma was investigated as a function of the distance from the Ar plasma zone. Changes in distance between the PET film and the Ar plasma zone had a strong influence on the surface modification of the film. The direct Ar plasma treatment (distance between the PET film and Ar plasma zone = 0 cm) was effective in hydrophilic surface modification, but heavy etching reactions occurred during the modification. On the other hand, the remote Ar plasma treatment (distance between the PET film and Ar plasma zone = 80 cm) modified the PET film surfaces to be hydrophilic without heavy etching reactions, although the hydrophilicity of the PET was lower than that by the direct Ar plasma. The remote Ar plasma treatment was distinguished from the direct Ar plasma treatment from the viewpoint of degradation reactions. The remote Ar plasma treatment rather than the direct Ar plasma treatment was an adequate procedure for surface modification and caused less polymer degradation on the film surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 808–815, 2001;2-B

2686. Shimizu, R.N., and N.R. Demarquette, “Evaluation of surface energy of solid polymers using different methods,” J. Applied Polymer Science, 76, 1831-1845, (2000).

In the present work, contact angles formed by drops of diethylene glycol, ethylene glycol, formamide, diiodomethane, water, and mercury on a film of polypropylene (PP), on plates of polystyrene (PS), and on plates of a liquid crystalline polymer (LCP) were measured at 20°C. Then the surface energies of those polymers were evaluated using the following three different methods: harmonic mean equation and geometric mean equation, using the values of the different pairs of contact angles obtained here; and Neumann's equation, using the different values of contact angles obtained here. It was shown that the values of surface energy generated by these three methods depend on the choice of liquids used for contact angle measurements, except when a pair of any liquid with diiodomethane was used. Most likely, this is due to the difference of polarity between diiodomethane and the other liquids at the temperature of 20°C. The critical surface tensions of those polymers were also evaluated at room temperature according to the methods of Zisman and Saito using the values of contact angles obtained here. The values of critical surface tension for each polymer obtained according to the method of Zisman and Saito corroborated the results of surface energy found using the geometric mean and Neumann's equations. The values of surface energy of polystyrene obtained at 20°C were also used to evaluate the surface tension of the same material at higher temperatures and compared to the experimental values obtained with a pendant drop apparatus. The calculated values of surface tension corroborated the experimental ones only if the pair of liquids used to evaluate the surface energy of the polymers at room temperature contained diiodomethane. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1831–1845, 2000;2-Q

2864. Agbezuge, L., and F. Wieloch, “Estimation of interfacial tension components for liquid-solid system from contact angle measurements,” J. Applied Polymer Science, 27, 271-275, (Jan 1982).

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.

2960. Lindner, M., N. Rodler, M. Jesdinszki, M. Schmid, and S. Sangerlaub, “Surface energy of corona treated PP, PE and PET films, its alteration as function of storage time and the effect of various corona dosages on their bond strength after lamination,” J. Applied Polymer Science, 135, 1-9, (Mar 2018).

The aim of this study was to analyze how corona dosages above recommended levels affect film surface energy and hydrophobic recovery of such treated film surfaces as well as laminate bond strength of laminates made of these films. The adhesive for lamination was a polyurethane-adhesive with a dry film thickness of ∼5 µm. Polar and dispersive parts of the surface energy were measured frequently according to DIN 55660-2 (Owens–Wendt–Rabel-and-Kaelble method) for up to 140 days after corona treatment. The corona dosage had a value of up to 280 W min/m2. Laminate bond strength was measured according to DIN 55543-5. The effect of corona treatment was highest for low-density polyethylene (PE-LD) films, mean for biaxial-oriented polypropylene (PP-BO) films, and lowest for biaxial-oriented poly(ethylene terephthalate) (PET-BO) films. With increasing storage time, surface energy decreased, as expected. The higher the effect of corona treatment, the faster the polar part of surface energy decreased. At PE-LD, laminate bond strength increased with a higher corona dosage from 0.05 to 8.87 mN/15 mm, whereas at PET-BO and PP-BO laminate bond strength was so high that samples teared before delamination during bond strength testing. By our results is shown that corona dosages above recommended levels resulted in higher laminate bond strength. Only at PP-BO a reduction of laminate bond strength due to “overtreatment” was be observed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45842.

2973. Gupta, B., J. Hilborn, C. Hollenstein, C.J.G. Plummer, R. Houriet, and N. Xanthopoulus, “Surface modification of polyester films by RF plasma,” J. Applied Polymer Science, 78, 1083-1091, (Aug 2000).

Plasma treatment of PET films was carried out under argon, followed by exposure to an oxygen atmosphere. The films underwent considerable changes in surface composition and morphology, as demonstrated by contact angle measurements, FTIR-ATR, AFM, and XPS. It was found that the surface acquired oxygen containing polar functional groups such as Single BondCDouble BondO, Single BondOH, and Single BondOOH, which increased in number as the plasma treatment time increased. During storage, the treated films underwent significant surface reorganization, and both the time and temperature contributed to the increase in the contact angle. As revealed by AFM measurements, these changes were accompanied by an increase in roughness in the form of ridges. The ridges were observed to grow in height with increasing treatment time, although their spacing showed little evolution. A correlation among the observations obtained from various techniques was established, giving a comprehensive picture of the structure and dynamics of plasma-treated PET surfaces. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1083–1091, 2000

2029. Castner, D.G., B.D. Ratner, and A.S. Hoffman, “Surface characterization of a series of polyurethanes by X-ray photoelectron spectroscopy and contact angle methods,” J. Biomaterials Science, 1, 191-206, (1989).

X-ray photoelectron spectroscopy (XPS) and contact angle methods were used to examine the surfaces of an homologous series of poly(ether urethane) (PEU) samples before and after cleaning treatments. Four PEU films with Shore hardnesses varying from 45 to 75 D were studied as well as two commercially available intravenous catheters of related PEUs. The four as received PEU films have similar surface compositions (~79% C, ~17% O, ~2% N, and ~ 2% Si) although they differ in bulk composition. Critical surface tension (γc) values are all similar and high (45-46 dynes/cm). The similarity in the surfaces of the four PEUs, despite the differences in their mechanical properties, demonstrates that surface properties do not necessarily reflect bulk properties. Soap washing and methanol-acetone extraction of the PEU films resulted in surfaces more representative of the bulk compositions of the PEUs. Analysis of the intravenous catheters confirmed that they are lubricated with PDMS, a common practice in the medical device industry. This study documents the value of detailed surface analysis for an enhanced understanding of the surface zone of PEUs. It also illustrates how cleaning protocols can remove labile surface species.

367. Triolo, P.M., and J.D. Andrade, “Surface modification and characterization of commonly used catheter materials,” J. Biomedical Materials Research, 17, 129-147, (1983).

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.

1802. Lelah, M.D., T.G. Grasel, J.A. Pierce, and S.L. Cooper, “The measurement of contact angles on circular tubing surfaces using the captive bubble technique,” J. Biomedical Materials Research, 19, 1011-1015, (1985).

Circular tubings are used extensively in biomedical implants and devices. It is desirable to determine contact angles on the inner or outer surfaces of such tubing in its final fabricated form. In this study, a technique for the measurement of contact angles on tubing surfaces in an aqueous environment is reported. This has particular applications to biomaterials research, where polymer tubings contact the biologic environment. In this technique, air or octane captive bubble dimensions can be measured, and an underwater contact angle calculated from these dimensions. The validity of the technique was experimentally confirmed using Solution Grade Biomer and NIH standard polyethylene surfaces.

1820. Reichert, W.M., F.E. Filisko, and S.A. Barenberg, “Polyphosphazenes: Effect of molecular motions on thrombogenesis,” J. Biomedical Materials Research, 16, 301-312, (1982).

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.

2770. Kilpadi, D.V., and J.E. Lemons, “Surface energy characterization of unalloyed titanium implants,” J. Biomedical Materials Research, 28, 1419-1425, (Dec 1994).

Osteointegration is dependent on a variety of biomechanical and biochemical factors. One factor is the wettability of an implant surface that is directly influenced by its surface energy. This investigation used the Zisman plot to determine critical surface energy. The effects of surface treatment, bulk grain size, and surface roughness on the critical surface tension of unalloyed titanium (Ti) were examined. Radio frequency glow discharge-treated Ti had the highest critical surface tension, followed by the passivated and heat-sterlized conditions. Titanium with no surface treatment had the lowest critical surface tension. The surface energy of Ti with an average grain size of 23 μm was not significantly different from that with a grain size of 70 μm. Surface roughness was shown to cause significant difference in measurements and definitely should be considered in studies of this kind. © 1994 John Wiley & Sons, Inc.

309. Sanchez-Rubio, M., J.R. Castellanos-Ortega, and J.E. Puig, “An analytical balance as tensiometer and densimeter,” J. Chemical Education, 68, 158-160, (1991).

How to convert an analytical balance into an accurate ring tensiometer or densimeter.

1514. Kabza, K., J.E. Gestwicki, and J.L. McGrath, “Contact angle goniometry as a tool for surface tension measurements of solids, using Zisman plot method: A physical chemistry experiment,” J. Chemical Education, 77, 63-65, (Jan 2000).

The paper describes a physical chemistry experiment for measurement of surface tension of solids. It includes description of the Zisman-plot method for obtaining the surface tensions of solids as well as a detailed experimental procedure for surface tension measurements using contact angle goniometry. Four surfaces were analyzed and the critical surface tension (gc) for each of them was obtained. Excellent reproducibility was achieved despite measurement of less accurate Young's contact angles. The experiment includes an extensive data analysis section combined with graphical interpretation of the results. It can be included in an undergraduate physical chemistry laboratory sequence on its own or combined with existing experiments pertaining to surface phenomena.

2774. Lamour, G., A. Hamraoui, A. Buvailo, Y. Xing, S. Keuleyan, V. Prokash, et al, “Contact angle measurements using a simplified experimental setup,” J. Chemical Education, 67, 1403-1407, (Dec 2010).

A basic and affordable experimental apparatus is described that measures the static contact angle of a liquid drop in contact with a solid. The image of the drop is made with a simple digital camera by taking a picture that is magnified by an optical lens. The profile of the drop is then processed with ImageJ free software. The ImageJ contact angle plugin detects the edge of the drop and fits its profile to a circle or an ellipse. The tangent to the triple line contact is calculated and drawn by the ImageJ software, thus, returning the value of the contact angle with acute precision on the measurement.

47. Cahn, J.W., “Critical point wetting,” J. Chemical Physics, 66, 3667-3672, (1977).

It is shown that in any two‐phase mixture of fluids near their critical point, contact angles against any third phase become zero in that one of the critical phases completely wets the third phase and excludes contact with the other critical phase. A surface layer of the wetting phase continues to exist under a range of conditions when this phase is no longer stable as a bulk. At some temperature below the critical, this perfect wetting terminates in what is described as a first‐order transition of the surface. This surface first‐order transition may exhibit its own critical point. The theory is qualitatively in agreement with observations.

104. Fowkes, F.M., and W.M. Sawyer, “Contact angles and boundary energies of a low energy solid (letter),” J. Chemical Physics, 20, 1652, (1952).

213. Lee, C.Y., J.A. McCammonn and P.J. Rossky, “The structure of liquid water at an extended hydrophobic surface,” J. Chemical Physics, 80, 4448-4455, (1984).

Molecular dynamics simulations have been carried out for liquid water between flat hydrophobic surfaces. The surfaces produce density oscillations that extend at least 10 Å into the liquid, and significant molecular orientational preferences that extend at least 7 Å into the liquid. The liquid structure nearest the surface is characterized by “dangling” hydrogen bonds; i.e., a typical water molecule at the surface has one potentially hydrogen‐bonding group oriented toward the hydrophobic surface. This surface arrangement represents a balance between the tendencies of the liquid to maximize the number of hydrogen bonds on the one hand, and to maximize the packing density of the molecules on the other. A detailed analysis shows that the structural properties of the liquid farther from the surface can be understood as effects imposed by this surface structure. These results show that the hydration structure of large hydrophobic surfaces can be very different from that of small hydrophobic molecules.

316. Schonhorn, H., “Theoretical relationship between surface tension and cohesive energy density,” J. Chemical Physics, 43, 2041-2043, (1965).

1485. Joanny, J.F., and P.G. de Gennes, “A model for contact-angle hysteresis,” J. Chemical Physics, 81, 552-562, (1984).

We discuss the behavior of a liquid partially wetting a solid surface, when the contact angle at equilibrium θ0 is small, but finite. The solid is assumed to be either flat, but chemically heterogeneous (this in turn modulating the interfacial tensions), or rough. For weak heterogeneities, we expect no hysteresis, but the contact line becomes wiggly. For stronger heterogeneities, we first discuss the behavior of the contact line in the presence of a single, localized defect, and show that there may exist two stable positions for the line, obtained by a simple graphic construction. Hysteresis shows up when the strength of the defect is above a certain threshold. Extending this to a dilute system of defects, we obtain formulas for the “advancing” and “receding” contact angles θa, θr, in terms of the distribution of defect strength and defect sharpness. These formulas might be tested by controlled contamination of a solid surface.

1949. Murphy, W.J., M.W. Roberts, and J.R.H. Ross, “Contact angle studies of some low energy polymer surfaces,” J. Chemical Society, Faraday Transactions 1, 68, 1190-1199, (1972).

We have explored the possibility of acquiring information on the molecular nature of some novel polymer films by following Zisman's approach of determining the critical surface tension γC which is considered to reflect the molecular composition of the solid surface. This led us to obtain equilibrium contact angle data, using both a series of pure liquids and various alcohol solutions, not only with the polymer films but also with solid surfaces of polystyrene and polymethylmethacrylate.

Lower values of γC were obtained with the solutions than with the pure liquids; these lower values are attributed to the preferential adsorption of the alcohol molecules at both the polymer-liquid and the polymer-vapour interfaces. The value of γC depends on the alcohol used, and is relatively independent of the solid : it is inferred that the alcohol is adsorbed with the hydroxyl group towards the polymer surface.

It is concluded that in certain cases, the value of γC obtained using solutions cannot be used as being characteristic of the solid (as has been suggested by Zisman), and that changes at the solid-vapour interface cannot be neglected when interpreting contact angle data. Several sets of data reported in the literature are discussed from this viewpoint. The Gibbs adsorption isotherms is applied to the contact angle data and the results add further weight to the conclusions regarding the occurrence of adsorption at both interfaces.

1580. Herbert, P.A.F., and E. Bourdin, “New generation atmospheric pressure plasma technology for industrial on-line processing,” J. Coated Fabrics, 28, (1999).

57. Cheever, G.D., “Evaluation of heterogeneous surfaces by contact angle distributions,” J. Coatings Technology, 58, 37-42, (Jan 1986).

250. Munro, H.S., and D.I. McBriar, “Influence of post treatment storage on the surface chemistry of plasma oxidized polymers,” J. Coatings Technology, 60, 41-46, (Nov 1988).

368. Tsutsui, K., A. Iwata, and S. Ikeda, “Plasma surface treatment of polypropylene-containing plastics,” J. Coatings Technology, 61, 65-72, (Sep 1989).

Low-pressure plasma treatment has been introduced for the practical pretreatment of automobile bumpers. The differences between the conventional solvent vapor pretreatment and low-pressure plasma or corona treatment, are shown schematically.

564. Schwartz, J., “The importance of low dynamic surface tension in waterborne coatings,” J. Coatings Technology, 64, 65-73, (Sep 1992).

Low dynamic surface tension is an important factor in achieving superior film formation in water-borne coatings. Dynamic coating application methods require surfactants with low dynamic surface tensions in order to prevent defects such as retraction, crawling and cratering. Comparative basic and empirical data are presented that will demonstrate the ability of acetylenic diols to lower the dynamic surface tension of water-borne coatings and hence improve the quality of the cured film.

607. Zisman, W.A., “Surface energetics of wetting, spreading, and adhesion,” J. Coatings Technology, 44, (1972).

Progress of research on wetting, spreading, and liquid-to-solid adhesion is reviewed with emphasis on advances since 1963. Carefully controlled experiments with pure materials, clean solids, special atmospheres, and thermodynamically acceptable physical conditions have resulted in new knowledge of surface science, polymer properties, and the role of interfering properties and chemicals. New uses and relationships have already been produced in many fields of technology and science. Recent advances shed much light on molecular conformational differences, polymer tacticity, and hydrogen bonding. Several current research problems are identified.

1691. Al-Turaif, H., “Relationship between surface chemistry and surface energy of different shape pigment blend coatings,” J. Coatings Technology and Research, 5, 85-91, (Mar 2008).

The influence of pigment shapes and pigment blends on the surface energy was investigated and compared with the surface chemistry of pigmented latex coatings. The coatings were made of different volume ratios of two pigments: plate-like kaolin clay pigment and prismatic precipitated calcium carbonate (PCC) pigment. These were mixed together with carboxylated styrene–butadiene–acrylonitrile latex (SBA), and applied over nonabsorbent substrates as well as absorbent substrates. The composition of the surface of the coatings was investigated by X-ray photoelectron spectroscopy (XPS). Two approaches were used to estimate the total surface energy and the components of the coatings: a conventional approach—“the Kaelble approach”—and a more modern approach—“the van Oss approach.” Pigment blends with different shapes and increments caused a change in the surface chemistry and the surface energy of the latex coatings. As the prismatic PCC pigment particles increased in the kaolin/SBA coating system, the SBA latex content at the coating surface increased and the total surface energy of the coating decreased. This is valid for both nonabsorbent as well as absorbent substrates. It was found that there was a strong correlation between the surface energy and the surface composition. The surface energy of the coatings estimated by the Van Oss approach was always lower than that estimated by the Kaelble approach. Colloidal interactions between pigment–pigment and/or pigment–binder were thought to play an essential role in determining the final coating surface energy and its components. Changes in the surface latex content and the surface energy due to the different pigment blends investigated were found to fit straight-line equations.

109. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, I. Polytetrafluoroethylene,” J. Colloid Science, 5, 514-531, (1950).

110. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, II. Modified tetrafluoroethylene polymers,” J. Colloid Science, 7, 109-121, (1952).


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