Isotropic-nematic phase transition of polydisperse clay rods

Woolston, Phillip; Duijneveldt, Jeroen S. van

doi:10.1063/1.4919887

Cited by 12 publications

(14 citation statements)

References 33 publications

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“…In general, rods of polydisperse lengths result in size fractionation, widening of the biphasic region [45,77,78], changes in the order parameter, and repressed smectic phase formation [77]. Diameter distribution also has some influence, but diameters are typically more uniform and length effects dominate the change in aspect ratio and phase behavior.…”

Section: Length Dispersity Of 1d Materialsmentioning

confidence: 99%

The Effects of Size and Shape Dispersity on the Phase Behavior of Nanomesogen Lyotropic Liquid Crystals

et al. 2020

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Self-assembly of anisotropic nanomaterials into fluids is a key step in producing bulk, solid materials with controlled architecture and properties. In particular, the ordering of anisotropic nanomaterials in lyotropic liquid crystalline phases facilitates the production of films, fibers, and devices with anisotropic mechanical, thermal, electrical, and photonic properties. While often considered a new area of research, experimental and theoretical studies of nanoscale mesogens date back to the 1920s. Through modern computational, synthesis, and characterization tools, there are new opportunities to design liquid crystalline phases to achieve complex architectures and enable new applications in opto-electronics, multifunctional textiles, and conductive films. This review article provides a brief review of the liquid crystal phase behavior of one dimensional nanocylinders and two dimensional nanoplatelets, a discussion of investigations on the effects of size and shape dispersity on phase behavior, and outlook for exploiting size and shape dispersity in designing materials with controlled architectures.

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Section: Length Dispersity Of 1d Materialsmentioning

confidence: 99%

The Effects of Size and Shape Dispersity on the Phase Behavior of Nanomesogen Lyotropic Liquid Crystals

et al. 2020

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“…Next, one assumes that the function α(ω) can be expanded in terms of the tensorial quantities ((2k + 1)!!/k!) ω (k) [see (6)], where the prefactors are determined by their orientational averages, Q i (k) . Following [29,49], we restrict this expansion to terms involving k = 2 and k = 4.…”

Section: Ideal Contributionmentioning

confidence: 99%

“…Inserting ( 12) into (4), noting that the angular integrals (weighted by the ODFs) in (4) lead to orientational averages, and using the definition of the tensorial order parameter [see (6)] one finds…”

Section: Excess Contributionmentioning

confidence: 99%

“…Already in thermodynamic equilibrium, such mixtures display a very rich, entropy-driven phase behavior [1,2,3,4,5], characterized by the interplay of orientational ordering, (depletion-induced) condensation and demixing. A recent example is an experimental study of polydisperse clay rods which show an isotropic-nematic phase transition on increasing concentration [6]. From the theoretical side, such phase diagrams have been studied, e.g., by Onsager theory [7] and by more general free energy functionals [8,9,10] in the framework of classical density functional theory (DFT), as well as by computer simulations [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Binary mixtures of rod-like colloids under shear: microscopically-based equilibrium theory and order-parameter dynamics

Lugo-Frías

Klapp

2016

J. Phys.: Condens. Matter

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Abstract. This paper is concerned with the dynamics of a binary mixture of rodlike, repulsive colloidal particles driven out of equilibrium by means of a steady shear flow (Couette geometry). To this end we first derive, starting from a microscopic density functional in Parsons-Lee approximation, a mesoscopic free energy functional whose main variables are the orientational order parameter tensors. Based on this mesoscopic functional we then explore the stability of isotropic and nematic equilibrium phases in terms of composition and rod lengths. Second, by combining the equilibrium theory with the Doi-Hess approach for the order parameter dynamics under shear, we investigate the orientational dynamics of binary mixtures for a range of shear rates and coupling parameters. We find a variety of dynamical states, including synchronized oscillatory states of the two components, but also symmetry breaking behavior where the components display different in-plane oscillatory states.

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“…Basic examples range from clay suspension composed of thin sheets with variable diameter [14], mineral rods with strong length polydispersity [15][16][17], variable-length filamentous biopolymers such as cellulose nanocrystals [18] or actin [19], to polydisperse carbon-based nanotubes (CNTs) [20] and graphene oxide sheets [21].…”

Section: Introductionmentioning

confidence: 99%

Spinodal instabilities in polydisperse lyotropic nematics

Ferreiro-Córdova

Wensink

2016

The Journal of Chemical Physics

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Many lyotropic liquid crystals are composed of mesogens that display a considerable spread in size or shape affecting their material properties and thermodynamics via various demixing and multiphase coexistence scenarios. Starting from a generalized Onsager theory we formulate a generic framework that enables locating spinodal polydispersities as well as identifying the nature of incipient size fractionation for arbitrary model potentials and size distributions. We apply our theory to nematic phases of both hard rods and disks whose main particle dimension is described by a unimodal log-normal distribution. We find that both rod-based and discotic nematics become unstable at a critical polydispersity of about 20 %. We also investigate the effect of doping nematic assemblies with a small fraction of large species and highlight their effect on the stability of the uniform nematic fluid. We find that while rod-based are only weakly affected by the presence of large species, doping discotic nematics with very large platelets leads to a remarkable suppression of the spinodal instabilities. This could open up routes towards controlling the mechanical properties of nematic materials by manipulating the local stability of nematic fluid and its tendency to undergo fractionation-driven microphase separation.

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Isotropic-nematic phase transition of polydisperse clay rods

Cited by 12 publications

References 33 publications

The Effects of Size and Shape Dispersity on the Phase Behavior of Nanomesogen Lyotropic Liquid Crystals

The Effects of Size and Shape Dispersity on the Phase Behavior of Nanomesogen Lyotropic Liquid Crystals

Binary mixtures of rod-like colloids under shear: microscopically-based equilibrium theory and order-parameter dynamics

Spinodal instabilities in polydisperse lyotropic nematics

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