Ionic Conduction in Poly(ethylene glycol)-Functionalized Hexa-peri-hexabenzocoronene Amphiphiles

Discotic liquid crystals based on hexa-peri-hexabenzocoronenes (HBCs) symmetrically substituted with six poly(ethylene glycol) (PEG) chains and further doped with LiCF3SO3 (LiTf) salt at different [EG]:[Li+] ratios nanophase-separate in domains composed from HBC columns and PEG chains. These model amphiphiles behave as viscoelastic solids with a shear modulus of 5 × 106 Pa and an ionic conductivity of 10–5 S/cm at 373 K. At temperatures below 333 K an ionic superstructure is formed of higher shear modulus (108 Pa) that surrounds the HBC columns and follows the disks in their rotational motion. However, the ionic superstructure impedes ion transport. Substituting the HBC core with two PEG chains breaks the symmetry of the ionic superstructure and increases ionic conductivity by an order of magnitude while retaining a high shear modulus and a viscoelastic response. These findings demonstrate that PEG-functionalized HBCs have great potential as new electrolytes because they combine ionic conductivity with me...