Surfactant wormlike micellar solutions resemble “living” polymers, where continuous random breakage and reformation lead to a Poisson distribution of length scales at equilibrium for simple cases, and classic Maxwellian viscoelasticity in the limit where breakage is significantly more rapid than relaxation process. However, block copolymer wormlike micellar aqueous solution exhibits “non-livingness”, which is manifested by the non-equilibrium size distribution of wormlike micelles (WLMs) and the stable self-assembled structure in various conditions. In this study, a novel WLM system comprised of Pluronic block copolymer L121 in the ionic liquid, ethylammonium nitrate (EAN), was investigated to understand the relationship between self-assembled microstructures and non-linear rheology. Interestingly, the system was observed to show flow birefringence and shear thinning. Our research uses the state-of-the-art rheology-small angle neutron scattering (rheo-SANS and flow-SANS) to define the specific role of polymer dynamics and micelle breakage/reformation in this system. The exploration of the structure-property relationship reported here serves as a reference for formulating non-ionic WLMs in ionic liquids. It also provides insights useful for further applications in synthesis of iono-elastomers via crosslinking block copolymer WLMs in ionic liquids.

Microstructure-property relationship of polymeric wormlike micelles in a protic ionic liquid

255th National Meeting (2018)

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