Fluctuations and phase transitions of uniaxial and biaxial liquid crystals using a theoretically informed Monte Carlo and a Landau free energy density

Villada‐Gil, Stiven; Palacio‐Betancur, Viviana; Armas-Pérez, Julio C.; Pablo, Juan; Hernández-Ortíz, Juan P.

doi:10.1088/1361-648x/ab0394

Cited by 2 publications

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“…Minimization of the free energy functional was performed through a simulated annealing technique, as described in previous publications. [49][50][51] This involved sampling the free energy landscape by proposing changes to the tensor order parameter Q, and accepting them according to a Metropolis criteria. The sequence of accepted trial moves formed a Markov chain of configurations, with the probability of acceptance given by Calculating ΔF required the discretization of the system and a numerical integration technique.…”

Section: Methodsmentioning

confidence: 99%

“…[46][47][48] Minimization of each free energy functional was performed using a simulated annealing technique, as described in previous publications. [49][50][51] The simulations were initialized using either a random configuration, the ansatz for BPs, twisted cylinder (TC), or the RSS configuration. We present the results using a reduced temperature, defined as is T* = (T − T NI )/T NI , where T is temperature, T NI is the clearing point temperature, and dimensionless nanodroplet size N = 4R/p 0 , which represents how many π-turns the director can make along the diameter of the nanodroplet.…”

Section: Simulations Of Phase Diagrams and Structures Of Chiral Lc Na...mentioning

confidence: 99%

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Strongly Chiral Liquid Crystals in Nanoemulsions

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absorption spectra due to surface plasmon resonances; [2] and the elastic moduli of polystyrene polymer films decrease substantially below 40 nm. [3] These examples highlight how nanoscopic confinement provides an important route for expanding the palette of materials structures and properties. Of particular relevance to the study reported in this paper, liquid crystals (LCs) are known to be strongly influenced by confinement. [4][5][6] For example, confinement of LCs can lead to changes to topological defects present in a sample, [4] alteration of optical properties [5] and changes to the way in which LCs respond to external fields (e.g., electric fields). [6] The majority of past studies, however, have focused on confinement of LCs on the micrometer-scale with fewer studies exploring the submicrometer-scale. [7][8][9][10][11][12][13][14][15][16][17][18][19] The majority of past studies of LCs in submicrometer-scale confinement have involved the use of droplets of nematic LCs. [9][10][11][14][15][16][17][18][19] These studies have reported internal LC configurations that depend on droplet size and the chemistry of the confining surfaces. Gupta et al. [19] observed that nematic droplets confined within multilayered polyelectrolyte shells of poly(styrene sulfonate) and poly(allylamine hydrochloride) changed from a bipolar configuration to a radial configuration as the diameter decreased from 3 µm to 700 nm. An additional study by Zou et al. [9] found that a confinementinduced bipolar-to-radial configuration transition in nematic droplets occurred when the LC was in contact with an adsorbed layer of poly(styrenesulfonic acid) but not poly(styrenesulfonate sodium), suggesting that the effects of confinement are modulated by surface interactions. In contrast, Peng et al. [18] have reported that nematic nanodroplets confined in SiO 2 capsules assumed a uniform internal alignment as the droplet diameter decreased to 200 nm, with either tangential or homeotropic anchoring on the capsules. In addition to changes in internal structure, phase transitions from isotropic to nematic phases have been reported to occur at temperatures that increase, decrease, or are invariant with nanodroplet size. [15,18] These conflicting observations likely arise from differences in interfacial chemistry and/or LC elastic properties. More broadly, however, they both highlight the opportunity that exists to tune LC properties via nanoconfinement but also pinpoint the need for additional studies of LC nanodroplets, including investigations of the effects of confinement on nanodroplets formed from LCs other than nematics.Limits on the resolution of far-field optical microscopy also make studies of LC droplets on the submicrometer-scale Liquid crystal (LC) emulsions represent a class of confined soft matter that exhibit exotic internal organizations and size-dependent properties, including responses to chemical and physical stimuli. Past studies have explored micrometer-scale LC emulsion droplets but little is known about LC ordering within subm...

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Section: Methodsmentioning

confidence: 99%