Shear-induced nematic phase in entangled rod-like PEEK melts

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

– We measure the self-diffusion of colloidal rod-like virus 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‖) and perpendicular (D⊥) ...

Interfacial Stick-Slip Transition in Simple Shear of Entangled Melts

Induced nematic-like phase in dipolar and quadrupolar colloids

We compute the one-body probability density function of a dipolar and a quadrupolar colloid driven by an external ordering field. Colloids with low structure in the absence of the external field, and with axially symmetric coupling potential are assumed. To compute the one-body probability density function, it is assumed that the dynamics of the colloid are given by the Smoluchowski equation wi...

Nematic effects and strain coupling in entangled polymer melts under strong flow.

We use small-angle neutron scattering (SANS) to study labeled short chains with and without the influence of an entangled and highly stretched surrounding environment of longer chains. We find unequivocal evidence of nematic effects as the blend chains in steady state flow are stretched a factor ∼1.5 more from the presence of the long chain nematic field. In the pure melt we confirm that the no...

Shear-induced displacement of isotropic-nematic spinodals

The shear dependent location of the isotropic-nematic spinodals in suspensions of bacteriophage fd is studied by means of time resolved birefringence experiments. The hysteresis in the birefringence on increasing and subsequently decreasing the shear-rate allows the determination of the location of points in the shear-rate vs concentration phase diagram between the isotropic-to-nematic and the ...