Configurational Microphase Separation in Elongational Flow of an Entangled Polymer Liquid

Single polymer dynamics in an elongational flow.

The stretching of individual polymers in a spatially homogeneous velocity gradient was observed through use of fluorescently labeled DNA molecules. The probability distribution of molecular extension was determined as a function of time and strain rate. Although some molecules reached steady state, the average extension did not, even after a approximately 300-fold distortion of the underlying f...

Phase and microphase separation in polymer blends

When two different polymers are mixed, they usually demix because of the slight repulsive interaction that exists between their monomers. This is general and may be related to phase separation in two component mixtures. When the same polymer blend is cross-linked in the one phase region, elastic forces develop and do not let this to occur. There results a microphase separation, with coexistence...

Elastic instabilities in planar elongational flow of monodisperse polymer solutions

We investigate purely elastic flow instabilities in the almost ideal planar stagnation point elongational flow field generated by a microfluidic optimized-shape cross-slot extensional rheometer (OSCER). We use time-resolved flow velocimetry and full-field birefringence microscopy to study the behavior of a series of well-characterized viscoelastic polymer solutions under conditions of low fluid...

Elongational Flows in Polymer Processing

Microphase separation in nonequilibrium biomembranes.

Compositional heterogeneities of cell membranes are thought to play an important role in many physiological processes. We study how variations in the membrane composition can be driven by nonthermal fluctuating forces and therefore show how these can occur relatively far from any critical point for the membrane. We show that the membrane steady state is not only controlled by the strength of th...