Visualization of anomalous penetrant transport in glassy poly(methyl methacrylate) utilizing high-resolution X-ray computed tomography

High-resolution X-ray computed tomography, a completely non-destructive technique that can be used to visualize features in the interior of opaque solids, was successfully adapted in a novel manner to examine the transport dynamics of methanol into glassy poly(methyl methacrylate) discs synthesized by an iniferter-mediated free radical polymerization. In addition to tracking methanol absorption and dimensional swelling, the time-dependent concentration profiles within the polymer disc were determined with higher resolution, lower scanning times, and no major geometry restrictions compared to previous state-of-the-art techniques. These profiles indicated non-Fickian transport behavior with sharp penetrant fronts and deviations from previously reported swelling profiles.