Director Configuration Transitions of Polyelectrolyte Coated Liquid-Crystal Droplets

Zou, Jianhua; Bera, Tanmay; Davis, Alicia A.; Liang, Wenlang; Fang, Jiyu

doi:10.1021/jp201909m

Cited by 41 publications

(45 citation statements)

References 37 publications

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“…25–27, 39–42 The results in this paper suggest that modulation of the charge of the LC interfaces caused by the presence of these species, and the accompanying changes in electrical double layers formed at these interfaces, are likely an important part of the overall balance of intermolecular interactions governing the ordering of LC at these interfaces (in addition to the widely recognized role of the interactions of the aliphatic tails of amphiphiles with LCs). 27 We also comment that understanding ionic phenomena in non-aqueous phases is relevant in a number of other contexts including recent studies of polyelectrolyte multilayers 35–37 and the electrophoresis of particles in oils. 16, 57, 58 …”

Section: Discussionmentioning

confidence: 99%

Influence of Simple Electrolytes on the Orientational Ordering of Thermotropic Liquid Crystals at Aqueous Interfaces

et al. 2011

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We report orientational anchoring transitions at aqueous interfaces of a water-immiscible, thermotropic liquid crystal (LC; nematic phase of 4′-pentyl-4-cyanobiphenyl) that are induced by changes in pH of the aqueous solution and the addition of simple electrolytes (NaCl) to the aqueous phase. Whereas measurements of the zeta potential on the aqueous side of the interface of LC-in-water emulsions prepared with 5CB confirm pH-dependent formation of an electrical double layer extending into the aqueous phase, quantification of the orientational ordering of the LC leads to the proposition that an electrical double layer is also formed on the LC-side of the interface with an internal electric field that drives the LC anchoring transition. Further support for this conclusion is obtained from measurements of the dependence of LC ordering on pH and ionic strength, as well as a simple model based on the Poisson-Boltzmann equation from which we calculate the contribution of an electrical double layer to the orientational anchoring energy of the LC. Overall, the results presented herein provide new fundamental insights into ionic phenomena at LC-aqueous interfaces, and expand the range of solutes known to cause orientational anchoring transitions at LC-aqueous interfaces beyond previously examined amphiphilic adsorbates.

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Section: Discussionmentioning

confidence: 99%

Influence of Simple Electrolytes on the Orientational Ordering of Thermotropic Liquid Crystals at Aqueous Interfaces

et al. 2011

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“…6 Specifically, LC droplets have been shown to undergo ordering transitions in response to the presence of lipids, 13, 16 surfactants, 37, 64 proteins, 13, 65–67 bile acids, 68 and bacteria and viruses. 63 Finally, we note that size-dependent ordering of LC droplets has also been exploited to design LC materials that respond to changes in ionic strength 69 and pH 45 of aqueous solutions and the presence of charged macromolecules. 43 …”

Section: Ordering Transitions In Lc Droplets Triggered Interactionmentioning

confidence: 96%

Design of Functional Materials Based on Liquid Crystalline Droplets

2013

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This brief perspective focuses on recent advances in the design of functional soft materials that are based on confinement of low molecular weight liquid crystals (LCs) within micrometer-sized droplets. While the ordering of LCs within micrometer-sized domains has been explored extensively in polymer-dispersed LC materials, recent studies performed with LC domains with precisely defined size and interfacial chemistry have unmasked observations of confinement-induced ordering of LCs that do not follow previously reported theoretical predictions. These new findings, which are enabled in part by advances in the preparation of LCs encapsulated in polymeric shells, are opening up new opportunities for the design of soft responsive materials based on surface-induced ordering transitions. These materials are also providing new insights into the self-assembly of biomolecular and colloidal species at defects formed by LCs confined to micrometer-sized domains. The studies presented in this perspective serve additionally to highlight gaps in knowledge regarding the ordering of LCs in confined systems.

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“…For example, Khan et al [90] demonstrated that monodisperse emulsions of microdroplets decorated with an amphiphilic block copolymer are sensitive to changes in the pH of the bulk aqueous phase, as a change in pH from 12 to 2 led to radial-to-bipolar ordering transitions. Similarly, Zou et al [102] showed that 5CB droplets coated with multilayers of poly(styrenesulfonate sodium (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) undergo radial-to-bipolar ordering transitions upon increasing the bulk concentration of sodium chloride (NaCl). While droplet size and the conditions of the confining solution can be manipulated to adjust the sensitivity of LC droplets to the presence of interfacial adsorbates, the response time of the droplets can be controlled by tailoring the chemistry of the droplet interface.…”

Section: Lc-in-water Emulsions As Sensorsmentioning

confidence: 99%

Chemical and biological sensing using liquid crystals

Carlton

Hunter

Miller

et al. 2013

Liquid Crystals Reviews

313

233

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The liquid crystalline state of matter arises from orientation-dependent, non-covalent interaction between molecules within condensed phases. Because the balance of intermolecular forces that underlies formation of liquid crystals is delicate, this state of matter can, in general, be easily perturbed by external stimuli (such as an electric field in a display). In this review, we present an overview of recent efforts that have focused on exploiting the responsiveness of liquid crystals as the basis of chemical and biological sensors. In this application of liquid crystals, the challenge is to design liquid crystalline systems that undergo changes in organization when perturbed by targeted chemical and biological species of interest. The approaches described below revolve around the design of interfaces that selectively bind targeted species, thus leading to surface-driven changes in the organization of the liquid crystals. Because liquid crystals possess anisotropic optical and dielectric properties, a range of different methods can be used to read out the changes in organization of liquid crystals that are caused by targeted chemical and biological species. This review focuses on principles for liquid crystal-based sensors that provide an optical output.

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Director Configuration Transitions of Polyelectrolyte Coated Liquid-Crystal Droplets

Cited by 41 publications

References 37 publications

Influence of Simple Electrolytes on the Orientational Ordering of Thermotropic Liquid Crystals at Aqueous Interfaces

Influence of Simple Electrolytes on the Orientational Ordering of Thermotropic Liquid Crystals at Aqueous Interfaces

Design of Functional Materials Based on Liquid Crystalline Droplets

Chemical and biological sensing using liquid crystals

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