Deuterium NMR study of slow relaxation dynamics in a polymer-like micelles system after flow-induced orientation

We present a first time-resolved deuterium NMR study on wormlike micelles under shear. For the investigation, a micellar system made of soybean phosphatidylcholine (lecithin), D2O, and cyclohexane was studied in the concentrated regime, in the vicinity of the isotropic/nematic transition but positioned in the equilibrium isotropic phase. The D2O dispersed in the micellar core was used as a probe to study the relaxation of a shearing-induced nematic phase back to the isotropic liquid state, after cessation of shear. The whole process was followed through time-resolved deuterium spectra and was characterized by a continuous decrease of the measured quadrupolar splitting, proportional to the nematic order parameter.