Self-Assembly of Pluronic F127 Diacrylate in Ethylammonium Nitrate: Structure, Rheology, and Ionic Conductivity before and after Photo-Cross-Linking

The self-assembly of an end-functionalized PEO106-PPO70-PEO106 triblock copolymer (BCP) with acrylic end groups (Pluronic F127 diacrylate or FDA) in a protic ionic liquid (deuterated ethylammonium nitrate, dEAN) is studied using small-angle neutron scattering, shear rheology, and dielectric spectroscopy. This functionalization constitutes less than 1 wt % of the copolymer and has no effect on micelle formation in dEAN. The sol gel transition and the supra molecular crystal structure of the concentrated FDA/dEAN solutions are also found to be unaffected by the acrylation of the end groups. Photo-cross-linking results in viscoelasticity enhancement of the FDA/dEAN solutions with FDA contents below the gel point. Cross-linking gels produces soft elastomers with exceptional elasticity and conductivity comparable to the un-cross-linked solutions. Tuning BCP microstructure via self-assembly in ionic liquids followed by chemical cross-linking is shown to be a promising route for the design of materials with specific mechanical properties and ionic conductivities.