Induced Microphase Separation in Hybrid Composite Polymer Electrolytes Based on Poly(acrylonitrile-r-butadienes) and Ionic Liquids

Novel hybrid, composite polymer electrolytes (HCPEs) based on poly(acrylonitrile-r-butadiene) (PAN-r-PB), CN-modified silica nanoparticles (CN-MSNs), Li triflate, and ionic liquids (ILs) are synthesized. Using a combination of methods, it is demonstrated that these materials segregate into PAN-rich and PB-rich phases, the behavior of which changes depending on the IL type. The incorporation of ILs containing hexyl and octyl substituents at the imidazolium rings leads to a higher mobility of the PB-rich phase and a decrease of the density of the neighboring PAN-rich phase, allowing an improvement of the Li ion conductivity. However, with an increase of the substituent length from decyl to dodecyl, ordering of the hydrophobic tails in the PB-rich phase leads to both stiffening of the latter and corresponding ordering of the ionic pairs of ILs, resulting in a decreased conductivity. The results of this work are broadly applicable for controlling the structure and properties of polymeric materials exhibiting microphase segregation.