Hierarchical organization in liquid crystal-in-liquid crystal emulsions

Mushenheim, Peter C.; Abbott, Nicholas L.

doi:10.1039/c4sm01651c

Cited by 20 publications

(26 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The propulsion is force-free (as the thrust force of the flagella is compensated by a viscous drag force) and torque free. If the LCLC is aligned in the planar fashion, the bacteria swim along the director, provided their concentration is low [8,15,29,30,36]. When the alignment is homeotropic, = ( ) n 0, 0, 1 , 0 previous experiments with P. mirabilis in thick cells (thicker than the bacterial length) showed that the bacteria remain parallel ton 0 and thus get stuck at the bounding plates.…”

Section: Vsp and Hsw Statesmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic states of swimming bacteria in a nematic liquid crystal cell with homeotropic alignment

et al. 2017

View full text Add to dashboard Cite

Flagellated bacteria such as Escherichia coli and Bacillus subtilis exhibit effective mechanisms for swimming in fluids and exploring the surrounding environment. In isotropic fluids such as water, the bacteria change swimming direction through the run-and-tumble process. Lyotropic chromonic liquid crystals (LCLCs) have been introduced recently as an anisotropic environment in which the direction of preferred orientation, the director, guides the bacterial trajectories. In this work, we describe the behavior of bacteria B. subtilis in a homeotropic LCLC geometry, in which the director is perpendicular to the bounding plates of a shallow cell. We demonstrate that the bacteria are capable of overcoming the stabilizing elastic forces of the LCLC and swim perpendicularly to the imposed director (and parallel to the bounding plates). The effect is explained by a finite surface anchoring of the director at the bacterial body; the role of surface anchoring is analyzed by numerical simulations of a rod realigning in an otherwise uniform director field. Shear flows produced by a swimming bacterium cause director distortions around its body, as evidenced both by experiments and numerical simulations. These distortions contribute to a repulsive force that keeps the swimming bacterium at a distance of a few micrometers away from the bounding plates. The homeotropic alignment of the director imposes two different scenarios of bacterial tumbling: one with an 180°r eversal of the horizontal velocity and the other with the realignment of the bacterium by two consecutive 90°turns. In the second case, the angle between the bacterial body and the imposed director changes from 90°to 0°and then back to 90°; the new direction of swimming does not correlate with the previous swimming direction. with a relatively flat rigid polyaromatic core and polar groups at the periphery [11][12][13]. In water, these molecules aggregate face-to-face in order to minimize the areas of unfavorable contact with water. Unlike their surfactantbased micellar and thermotropic counterparts, the LCLCs are not toxic to biological organisms [14].Recent experiments demonstrate that the prevailing direction of swimming is parallel to the directorn, i.e. to the average direction of LCLC orientation ( º -n n, = |ˆ| n 1) [7,8]. The orientational order of the LCLC environment can be controlled by temperature, the concentration of liquid crystal organic molecules, external electromagnetic fields and by surface alignment of the director [9,11,12]. The dispersion of swimming bacteria in LCLC, also called a living liquid crystal [8], offers new opportunities to control the dynamic behavior of the bacteria.The studies of swimming bacteria in LCLCs have been performed mostly for sandwich-type cells, in which the LCLC is confined between two glass plates, with the director being uniformly aligned along a certain direction in the plane of the cell (planar alignment). It has been shown that rod-like flagellated bacteria prefer to swim along the director [7,8,15,16]. It is ass...

show abstract

Section: Vsp and Hsw Statesmentioning

confidence: 99%

“…When placed in an LCLC, elongated flagellated bacteria, such as Escherichia coli [6], P. mirabilis [7,30,36], and B. subtilis [8,15], all preserve their ability to swim [15,36], being propelled by the rotation of flagella bundles. The CCW rotation of the flagella is counterbalanced by a CW rotation of the bacterial body.…”

Section: Vsp and Hsw Statesmentioning

confidence: 99%

Dynamic states of swimming bacteria in a nematic liquid crystal cell with homeotropic alignment

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Finally, we note that a recent study has reported the formation of LC-in-LC emulsions. These emulsions were formed by dispersing droplets of a thermotropic LC, such as 5CB, within a continuous aqueous lyotropic chromonic LC phase (95). Interestingly, the orientations of the two immiscible LC phases were shown to be coupled to one another such that the symmetry axis of bipolar 5CB droplets assumed an orientation that was orthogonal to the far-field director of the continuous chromonic LC phase.…”

Section: Emulsions Of Liquid Crystalsmentioning

confidence: 99%

Design of Responsive and Active (Soft) Materials Using Liquid Crystals

Büküşoğlu

Pantoja

Mushenheim

et al. 2016

Annu. Rev. Chem. Biomol. Eng.

Self Cite

116

114

View full text Add to dashboard Cite

Liquid crystals (LCs) are widely known for their use in liquid crystal displays (LCDs). Indeed, LCDs represent one of the most successful technologies developed to date using a responsive soft material: An electric field is used to induce a change in ordering of the LC and thus a change in optical appearance. Over the past decade, however, research has revealed the fundamental underpinnings of potentially far broader and more pervasive uses of LCs for the design of responsive soft material systems. These systems involve a delicate interplay of the effects of surface-induced ordering, elastic strain of LCs, and formation of topological defects and are characterized by a chemical complexity and diversity of nano- and micrometer-scale geometry that goes well beyond that previously investigated. As a reflection of this evolution, the community investigating LC-based materials now relies heavily on concepts from colloid and interface science. In this context, this review describes recent advances in colloidal and interfacial phenomena involving LCs that are enabling the design of new classes of soft matter that respond to stimuli as broad as light, airborne pollutants, bacterial toxins in water, mechanical interactions with living cells, molecular chirality, and more. Ongoing efforts hint also that the collective properties of LCs (e.g., LC-dispersed colloids) will, over the coming decade, yield exciting new classes of driven or active soft material systems in which organization (and useful properties) emerges during the dissipation of energy.

show abstract

“…The relative polarizability anisotropy of 8CB and 5CB is also different. [19,20] Therefore, with the aid of an applied AC voltage, the anisotropic LC axis can be controlled, and thereby the molecular orientation takes place in the direction of the force action from its default position based on the applied rms value of the voltage. [21] This leads to an important physical phenomenon associated with the effective refractive index and phase shift experienced by the light travelling the LC medium and these effects can be observed by means of polarizers with an appropriate modification in the experimental setup.…”

Section: Phase Transitionsmentioning

confidence: 99%

Visible spectroscopy of 5CB/8CB liquid crystals

et al. 2015

View full text Add to dashboard Cite

Electro-optical properties of nematic liquid crystals (LCs) have attracted a great deal of research interest and have resulted in a number of practical applications in many areas. In the present study, wavelength dependence of electro-optical properties of two different types of nematic LCs and their binary mixtures are investigated. LCs used in this study are 5CB and 8CB and their mixtures in different proportions. The optical transmittance of the structures has been studied by means of visible spectroscopy by measuring the transmitted light intensity as a function of the wavelength under various driving AC electric field values. Experiments were carried out at the wavelength interval 380À780 nm at a constant temperature of 25 C in order to see the effect of the applied field alone.

show abstract

Hierarchical organization in liquid crystal-in-liquid crystal emulsions

Cited by 20 publications

References 46 publications

Dynamic states of swimming bacteria in a nematic liquid crystal cell with homeotropic alignment

Dynamic states of swimming bacteria in a nematic liquid crystal cell with homeotropic alignment

Design of Responsive and Active (Soft) Materials Using Liquid Crystals

Visible spectroscopy of 5CB/8CB liquid crystals

Contact Info

Product

Resources

About