Some Reflections on Acid–Base Solid Surface Free Energy Theories

Volpe, C. Della; Siboni, S.

doi:10.1006/jcis.1997.5124

Cited by 350 publications

(201 citation statements)

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“…56 However, IGC can be used to unambiguously measure the specific contribution to the free energy of adsorption, G sp , for a given polar adsorbate (in kJ/mol), determined as the difference of RTlnV n of the polar probe to the corresponding dispersive reference line in figure 4: 49 In addition, in the cases of MoS 2 and MoSe 2 , these surface energies are very similar to the values estimated from the solubility measurements shown in figure 3. This similarity suggests that while surface energy is not an ideal solubility parameter for these layered compounds (due to the scatter observed in figure 3), it can be used as a first order approximation.…”

Section: Measurement Of Surface Energy By Inverse Gas Chromatographymentioning

confidence: 66%

Solvent Exfoliation of Transition Metal Dichalcogenides: Dispersibility of Exfoliated Nanosheets Varies Only Weakly between Compounds

et al. 2012

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Abstract:We have studied the dispersion and exfoliation of four inorganic layered compounds, WS 2 , We found that the dispersed concentration of each material falls exponentially with  as predicted by solution thermodynamics. This work shows that solution thermodynamics and specifically solubility parameter analysis can be used as a framework to understand the dispersion of 2-dimensional materials. Finally, we note that in good solvents such as 2 cyclohexylpyrrolidone, the dispersions are temporally stable with >90% of material remaining dispersed after 100 hours. ToC figOver the last decade, 2-dimensional nanomaterials have become one of the most studied subfields of nanoscience. These developments have been spearheaded by research into graphene, a material that is unique due to its combination of thermal, electronic, optical and mechanical properties. 1-5 However, over the last few years, it has become clear that a range of other inorganic layered compounds can be mechanically exfoliated in small quantities to give 2-dimensional nanosheets with interesting properties. 6-10 For example, exfoliated hexagonal boron nitride has been used as a dielectric support in graphene-based transistors 11 while MoS 2 has been fabricated into sensors 10, 12 , transistors 13-15 and integrated circuits. 16 The availability of a wide range of 2-dimensional materials is important as it allows access to a broad palette of physical and chemical properties. A good example is provided by the family of transition metal dichalcogenides (TMDs). These materials have the chemical composition MX 2 where M is a transition metal (commonly, but not limited to Ti, Nb, Ta, Mo, W) and X is a chalcogen (i.e. S, Se, Te). As in graphite, these atoms are covalently bonded into nanosheets which stack into 3-dimensional crystals by van der Waals interactions. These materials are of particular interest because, depending on the combination of metal and chalcogen, the material can be semiconducting or metallic. 17 In addition, the bandgap can vary from a few hundred meV to a few eV, 17 suggesting these materials have potential as versatile electronic device materials.Furthermore, these materials have interesting electrochemical properties which make them suitable for applications such as battery electrodes. 18,19 As with graphene, many applications will require relatively large quantities of material suggesting that a solution processing route is required. 20 A number of possibilities exist. For example, it has been known for many years that materials such as MoS 2 can be exfoliated by 3 lithium intercalation. 21 However, such a route tends to result in structural deformations in some TMDs leading to considerably altered electronic properties. 22 Alternatively, TMDs can be synthesised in the liquid phase. 7,8 Probably the simplest route to liquid exfoliation of layered compounds is sonication assisted exfoliation in solvents [23][24][25][26][27][28][29] or aqueous surfactant solutions. 19,[30][31][32] Here, sonication results in the exfoliation of the ...

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Section: Measurement Of Surface Energy By Inverse Gas Chromatographymentioning

confidence: 66%

Solvent Exfoliation of Transition Metal Dichalcogenides: Dispersibility of Exfoliated Nanosheets Varies Only Weakly between Compounds

et al. 2012

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“…Table 4 shows that no notable difference was observed in the total surface free energy obtained from the two different liquid parameters. The total surface free energy of aged wood samples (obtained using liquid parameters from Volpe and Siboni (1997)) were not significantly different. The acid-base components of aged wood samples decreased with increasing grit number.…”

Section: Surface Free Energy Componentsmentioning

confidence: 88%

“…This finding, inconsistent with that of Gindl that the base components were higher than the acid components , may be due to the different reference liquids and/or the different species of wood; more work is necessary to determine the basis of this discrepancy. As shown in Table 4, the base-acid component ratios for fresh wood obtained by the vOCG method (Van Oss et al 1988) using liquid parameters from Volpe and Siboni (1997) were considerably lower than those ratios obtained from Van Oss et al (1988). Table 4 shows that no notable difference was observed in the total surface free energy obtained from the two different liquid parameters.…”

Section: Surface Free Energy Componentsmentioning

confidence: 91%

“…Volpe and Siboni (1997) recalculated test liquid acid-base balances, resulting in a decrease in the base component compared to the vOCG method (Van Oss et al 1988). The acid-base values of reference liquids used according to vOCG and DVS are list in Table 1.…”

Section: Owrk Methodsmentioning

confidence: 99%

“…Depending on the surface to be examined and the selected test liquids, several methods are available for calculation of the surface energy of a solid. The earliest studies were based on critical surface tensions (Timmons and Zisman 1968), followed by the two liquids concept of harmonic (Gardner 1996, Maldas andKamdem 1999) and geometric means (Gardner 1996;Owens and Wendt 1969), the equation of state (Neumann et al 1974), and the Lifshitz-van der Waals/acid-base theory based on three liquids (Van Oss et al 1988;Volpe and Siboni 1997;Wålinder 2002).…”

Section: Introductionmentioning

confidence: 99%

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Wettability of Sanded and Aged Fast-growing Poplar Wood Surfaces: I. Surface Free Energy

et al. 2014

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The sanding process influences the surface morphology and chemical components of wood, which are two important factors that influence the surface free energy and wettability of wood. The objective of this study was to investigate the roughness of sanded poplar wood and the effects of sanding and aging on the surface free energy using different methods. The roughness parameter (Ra) decreased as the grit number increased, but no change was evident when the grit number increased from 120 to 240. The contact angle of water on the fresh wood samples decreased as the grit number increased. Fresh wood samples were more easily wetted by water than was the aged wood sample, and the contact angles increased as the surface roughness decreased. The surface free energy of sanded, aged wood obtained by the Zisman method may be unsuitable. For the fresh wood samples, the change of surface free energy and its components were not significantly changed when the grit number was higher than 120; for the aged wood samples, the dispersion component appeared to increase slightly as the grit number decreased. The effect of roughness on the acid/base component, acid component, and base component calculated by the vOCG method was unremarkable. The surface free energy of the wood samples (obtained using the liquid parameters provided by Volpe and Siboni (1997)) can effectively balance the relationship between the acid and base components.

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