Dispersive Component Of Surface Free Energy Research Articles

Effect of working gas on physicochemical and biological properties of CaP coatings deposited by RFMS

Thin calcium phosphate (CaP) coatings were deposited on titanium substrates by radio frequency magnetron sputtering of hydroxyapatite target in neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe). The influence of the working gas (Ne, Ar, Kr and Xe) on the wettability and biodegradation in the RPMI 1640 synthetic culture medium of the CaP coatings was investigated. This paper is the first comprehensive study of working gas effect on properties of the CaP coatings. There was an increase in the polar component of surface free energy (SFE) and a decrease in the dispersion component of SFE with an increase in the atomic mass of the working gas. All CaP coatings had a pronounced protective effect, reducing double the number of dead cells in culture compared to the Ti control. The most soluble CaP coatings formed in the atmosphere of Xe stimulated the hAMMSCs division, which led to an increase in the total number of cells (208% of the initial culture). Samples with CaP coatings formed in an inert gas atmosphere increased the gene expression (ALPL, BMP6, BMP2) in vitro . The most biocompatible coatings were those formed in the atmosphere of Xe and Ar.

Surface free-energy determination of copper wire using a large range of model liquids

In this paper, the surface free-energy of 700 µm-diameter copper wires as well as its dispersive and polar components has been determined. For this, the measurement method developed for assessing advancing and receding contact angles of liquids on vertical wires has been validated with polytetrafluoroethylene (PTFE) as a well-known material. Thus, it has been checked that the dynamic contact angles of different model liquids, such as dimethylformamide, tri-cresyl phosphate or ethylene glycol, on a PTFE wire held vertically are similar to those obtained on a PTFE plane surface. Then, the Owens–Wendt approach was chosen to determine the polar and dispersive components of surface free-energy of the PTFE wire using a large range of model liquids. A surface free-energy γPTFE = 18.7 ± 1.6 mN m−1 was obtained with a high dispersive component, γd ≈ 17.3 ± 1.0 mN m−1, in comparison with the polar one, γp ≈ 1.4 ± 0.6 mN m−1. Using the same approach for the copper wire, a surface free-energy γCu = 25.7 ± 0.7 mN m−1 was determined including mainly dispersive forces (γd ≈ 25.1 ± 0.5 mN m−1).

Impact of Perfluoro and Alkylphosphonic Self-Assembled Monolayers on Tribological and Antimicrobial Properties of Ti-DLC Coatings.

The diamond-like carbon (DLC) coatings containing 1.6%, 5.3% and 9.4 at.% of Ti deposited by the radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method on the silicon substrate were modified by n-decylphosphonic acid (DP) and 1H, 1H, 2H and 2H-perfluorodecylphosphonic acid (PFDP). The presence of perfluoro and alkylphosphonic self-assembled monolayers prepared by the liquid phase deposition (LPD) technique was confirmed by Fourier transform infrared spectroscopy (FTIR). It was shown that DP and PFDP monolayers on the surface of titanium incorporated diamond-like carbon (Ti-DLC) coatings had a huge influence on their wettability, friction properties, stability under phosphate- and tris-buffered saline solutions and on antimicrobial activity. It was also found that the dispersive component of surface free energy (SFE) had a significant influence on the value of the friction coefficient and the percentage value of the growth inhibition of bacteria. The dispersive component of SFE caused a reduction in the growth of bacteria and the friction coefficient in mili- and nano-newton load range. Additionally, both self-assembled monolayers prepared on Ti-DLC coatings strongly reduced bacterial activity by up to 95% compared to the control sample.

Tailoring the properties of deposited thin coating and print features in flexography by application of UV-ozone treatment

Printed functional materials are a rapidly growing area of interest for low-cost high-speed device manufacture with flexographic printing seen as a route to achieving this. The relationship between surface tension of the ink and surface free energy (SFE) of the photopolymer plate is a key for optimum performance. However, traditional methods of surface tension modification of the ink/coating often cannot be employed for functional inks. In this research, rapid, permanent modification of flexographic printing plate’s SFE is achieved through controlled UV-ozone treatment, and the effects of the treatment on the polar and dispersive component of SFE are analyzed by Fourier transform infrared attenuated total reflectance spectroscopy, swelling experiments, and roughness measurements. Printing trials using the modified printing plates reveal improved print uniformity and control of deposited ink layer thickness, as well as improved print features—particularly track and pad junctions which can be problematic for printed electronic applications. The ability to rapidly tailor printing plate SFE is of benefit to all volume printing applications. Furthermore, it is of critical importance for functional printing and printed electronics where surface tension of the ink is determined by the functional material and chemical modification is not possible or desirable.

The Application of Grey System Theory to Correlate Chemical Composition and Surface Free Energy of Asphalt Binders

Grey correlation analyses were carried out to determine which chemical components and chemical elements of asphalt binders are most related to surface free energy (SFE) measurements of asphalt binders. The total, dispersive, and polar SFE values were calculated for 23 Strategic Highway Research Program (SHRP) asphalt binders based on contact angle measurements by the sessile drop method and the chemical composition data of the 23 binders was obtained from previously published information. During the Grey correlation analysis, it was found that polar aromatics content has the largest effect on the total SFE and dispersion component of SFE, whereas saturates made the largest contribution to the polar component of SFE. Carbon (C) and hydrogen (H) made the largest contribution to the total, dispersion, and polar SFE; vanadium (V) content has the smallest effect on the total surface free energy, including its dispersion and polar parts.

Study of the polyelectrolyte multilayer thin films' properties and correlation with the behavior of the human gingival fibroblasts

The relation between fibroblast cell behavior and wettability parameters of different polyelectrolyte multilayers (PEM) was investigated. To this end, three types of film ending with polycations or polyanions were selected: poly( l-lysine)/poly( l-glutamic acid) (PGA/PLL) 5 and (PGA/PLL) 5–PGA, hyaluronan/PLL (HA/PLL) 5 and (HA/PLL) 5–HA, and poly(styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH) 10 and (PSS/PAH) 10–PSS. The film roughness and thickness were measured by AFM and optical waveguide lightmode spectroscopy (OWLS). Surface free energy (SFE), polar (acid, basic and acid–basic) and dispersive components of SFE were determined using the Van Oss approach by dynamic contact angle (DCA) measurements. Cell adhesion was quantified by fluorescent labeling using an image analysis system. Cell morphology was analyzed by scanning electron microscopy (SEM) and phase contrast microscopy. Cell proliferation was followed over a seven day period. Fibroblast adhesion and proliferation were strongly dependent on film type. SEM observations of cells on the different films agreed with the proliferation and adhesion tests.