When ions are moving through a nanophase-separated polymer, it’s complicated. Extensive efforts studying block copolymers with one block that is insulating and another block that transports ions have established that the morphology symmetry (cylinders, double gyroid, layers, etc.) and the orientation of these ordered morphologies affect ion conductivity. In Benjamin Ferko‘s recent paper in Chemistry of Materials (https://lnkd.in/e33i73wD), we explore the impact of alignment and solvent swelling on ion conductivity in a layer-forming multiblock copolymer ionomer. By making thin films with the layers in the plane and using interdigitated electrodes, we unsurprisingly found that aligning the dry polymer (filled gray) improved the ion conductivity relative to the dry isotropic polymer (open gray). Adding solvent to the aligned sample (filled blue) only modestly increased its conductivity. The largest increase was observed when the solvent swelled the bulk isotropic sample (open blue), and we attribute this to preferential swelling of the grain boundaries. These results indicate that polymer processing, which can affect both the orientation distribution and grain size, plays a critical role in determining ion conductivity in nanostructured polymers.
To facilitate this study of solvent swollen thin films, Ben designed and built sample chambers for broadband dielectric spectroscopy and grazing incidence X-ray scattering experiments. Importantly, these chambers control the temperature and the gaseous environment around the sample, often a saturated solvent atmosphere, during the experiments. These chambers are described in our recent paper in the Review of Scientific Instrumentation (https://lnkd.in/ewXK8rQ8). If you are interested in either of these chambers, we’re happy to share more details.
Ben is graduating with his PhD in materials science and engineering next week, and we wish him all the best as he starts at Green Tweed. The students inheriting the specialty sample chambers are grateful that he’ll be nearby and willing to answer questions. And we’ll all miss his expertise in polymer physics and with equipment! Congrats Ben!
See the full LinkedIn post here.
