Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces

Takaomi Suzuk,Yuya Yamada

doi:10.4236/jcpt.2015.53006

Takaomi Suzuk, Yuya Yamada

Open Access

https://doi.org/10.4236/jcpt.2015.53006

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Abstract

Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN·m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN·m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ·mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface.

Highlights

IntroductionThe relationship between the specific surface free energy (SSFE) and the contact angle of a liquid is shown by Young’s equation [1]:
The relationship between the specific surface free energy (SSFE) and the contact angle of a liquid is shown by Young’s equation [1]:γ SL + γ LV cosθ = γ S (1)where γS is the SSFE of the solid, γSL is the interfacial tension between the solid and the liquid, and γ LV isHow to cite this paper: Suzuki, T. and Yamada, Y. (2015) Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces
Fowkes [5] proposed that the surface tension could be described as a sum of the dispersion component and the polar component as, γ=S

Summary

Introduction

The relationship between the specific surface free energy (SSFE) and the contact angle of a liquid is shown by Young’s equation [1]:. D LV are dispersion and polar component of the surface tension of the liquid, respectively. The values of γS can be obtained from θ as ( ) γ LV 1+ cos= θ (4) This equation is widely accepted for studies of the SSFE of polymer surfaces [2]. We adopted this established experimental method to determine the SSFE of some inorganic crystals, ruby [7], quartz [8], and apatite [9], using contact angle of liquid droplet. We are studying alkali halide crystals, and discussing the detailed meaning of SSFE of crystal, especially dispersion and polar components of SSFE

Experimental

Results and Discussion

Conclusions