arXiv subjects

Edward Barry

Publications and source records attributed to Edward Barry.

3 recordsLinked to original sources

arXiv2011

Self-assembly of 2D membranes from mixtures of hard rods and depleting polymers

We elucidate the molecular forces leading to assembly of two dimensional membrane-like structures composed of a one rod-length thick monolayer of aligned rods from an immiscible suspension of hard rods and depleting polymers. We perform simulations which predict that monolayer membranes are thermodynamically stable above a critical rod aspect ratio and below a critical depletion interaction length scale. Outside of these conditions alternative structures such as stacked smectic columns or nematic droplets are thermodynamically stable. These predictions are confirmed using an experimental model system of virus rod-like molecules and non-adsorbing polymer. Our work demonstrates that collective molecular protrusion fluctuations alone are sufficient to stabilize membranes composed of homogenous rods with simple excluded volume interactions.

cond-mat.soft↗

arXiv2005

Entropy driven formation of a chiral liquid crystalline phase of helical filaments

We study the liquid crystalline phase behavior of a concentrated suspension of helical flagella isolated from {\it Salmonella typhimurium}. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rod-like shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy driven first order phase transition to a liquid crystalline state having a novel chiral symmetry.

cond-mat.soft↗

arXiv2005

Self-diffusion of rod-like viruses in the nematic phase

We measure the self-diffusion of colloidal rod-like virus {\it fd} in an isotropic and nematic phase. A low volume fraction of viruses are labelled with a fluorescent dye and dissolved in a background of unlabelled rods. The trajectories of individual rods are visualized using fluorescence microscopy from which the diffusion constant is extracted. The diffusion parallel ($D_{\parallel}$) and perpendicular ($D_{\perp}$) to the nematic director is measured. The ratio ($D_{\parallel}/D_{\perp}$) increases monotonically with increasing virus concentration. Crossing the isotropic-nematic phase boundary results in increase of $D_{\parallel}$ and decrease of $D_{\perp}$ when compared to the diffusion in the isotropic phase ($D_{iso}$).

cond-mat.soft↗