Ion Transport and Interfacial Dynamics in Disordered Block Copolymers of Ammonium-Based Polymerized Ionic Liquids

A series of diblock copolymers bearing a polymerized ionic liquid (polyIL) block (poly(N-(methacryloyloxy)ethyl-N,N-dimethyl-N-ethylammonium bis(trifluoromethylsulfonyl)imide)) and a noncharged block (poly(methyl methacrylate) (PMMA)) or poly(n-butyl methacrylate) (PBuMA)) were studied using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and broadband dielectric spectroscopy (BDS) to probe the effect of ion concentration on the morphology and ion transport in these polyelectrolytes. Two majority PMMA block copolymers, having mole ratios of the polyIL of 0.19 and 0.22, exhibited evidence of aggregation indicated by interfacial polarization in the dielectric spectra. The 0.19 mole ratio sample also displayed two distinct glass transitions by DSC. The SAXS measurements showed that no long-range order was present in these samples. The ionic conductivity of these samples were lower than the polyIL homopolymer due to hindered ion transport at th...