Equilibrium/Living polymers are a class of molecules that spontaneously self assemble to form reversible aggregates of one or more type of molecules in a solution or in a melt. We study, through computer simulations, a model system of segments which can spontaneously assemble to form large polymeric aggregates. We show that strength of short range attraction and long range repulsion between segments leads to randomly networked gel states even in very dilute solutions. The short range attraction favors the growth of polymers and long range repulsion stabilizes the percolating network. It is shown that shear flow induces a non trivial structural transitions in these systems. They exhibit shear thinning behavior through lamellar/columnar structure formation at high shear stresses and through alignment of individual segments at low shear stresses. Such a decrease in the viscosity with shear rate due to shear alignment is reported in many experiments. (This work appeared as a cover page article in the journal Soft Matter).
This research highlight was submitted by Prof. P. B. Sunil Kumar.