Strathprints logo
Strathprints Home | Open Access | Browse | Search | User area | Copyright | Help | Library Home | SUPrimo

Simulation of scattering and phase behavior around the isotropic–nematic transition of discotic particles

Fartaria, Rui P. S. and Javid, Nadeem and Sefcik, Jan and Sweatman, Martin B. (2012) Simulation of scattering and phase behavior around the isotropic–nematic transition of discotic particles. Journal of Colloid and Interface Science, 377 (1). pp. 94-104. ISSN 0021-9797

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

The detailed study of the isotropic-nematic phase transition in a system of discotic particles of aspect ratios L/D <= 0.1 presented here is relevant to a broad range of colloidal suspensions of chemically modified clay particles. Using Monte Carlo simulation techniques the equation of state, radial distribution functions, structure factors and normalized scattering intensities are calculated for each phase. The results are interpreted and related to previously reported free energy calculations [Fartaria and Sweatman, Chem. Phys. Lett. 478 (2009) 150], suggesting a nearly continuous isotropic-nematic transition for lower aspect ratios. Given this behavior we examined the structural information for each phase to determine how experimental scattering data might be used to distinguish the two phases. The radial distribution functions in each phase depend strongly on aspect ratio, and for larger aspect ratios a dramatic increase in the local ordering of discotic particles (represented here as cut-spheres) is observed just before the phase transition. However, this nearest-neighbor ordering seen in g(r) around r/D = 0.1 would hardly be discernible in experimental scattering data subject to usual statistical errors. The structure factors and scattering intensities were calculated for L/D = 0.1, 0.04 and 0.01 for the isotropic and nematic phases at and away from the isotropic-nematic transition. While the isotropic-nematic phase transition can be detected from the height and shape of the first scattering peak around 7QD for larger aspect ratios, this feature becomes much less discriminatory with decreasing aspect ratio. Instead, scattering intensities at low scattering vector amplitudes (Q -> 0) can be used for detection of the phase transition at low aspect ratios. These results provide useful insight to guide interpretation of X-ray and light scattering measurements for colloidal dispersions of thin platelets undergoing isotropic-nematic transitions. (C) 2012 Elsevier Inc. All rights reserved.

Item type: Article
ID code: 42324
Keywords: cut-sphere, algorithm, isotropic, nematic, phase transition, light scattering, clay, Monte Carlo, nanocomposite, dispersion, Chemical engineering, Biomaterials, Surfaces, Coatings and Films, Colloid and Surface Chemistry, Electronic, Optical and Magnetic Materials
Subjects: Technology > Chemical engineering
Department: Faculty of Engineering > Chemical and Process Engineering
Faculty of Science > Pure and Applied Chemistry
Technology and Innovation Centre > Bionanotechnology
Technology and Innovation Centre > Continuous Manufacturing and Crystallisation (CMAC)
Related URLs:
Depositing user: Pure Administrator
Date Deposited: 07 Dec 2012 16:26
Last modified: 27 Mar 2014 10:45
URI: http://strathprints.strath.ac.uk/id/eprint/42324

Actions (login required)

View Item