Status: this preprint is currently under review for the journal MR.
Static-Gradient NMR imaging for Depth-Resolved Molecular Diffusion in Amorphous Regions in Semicrystalline PTFE Film
Natsuki Kawabata,Naoki Asakawa,and Teruo Kanki
Abstract. Understanding spatially heterogeneous molecular diffusion in semicrystalline polymers is critical for elucidating interfacial dynamics in soft materials. This study employs static-gradient nuclear magnetic resonance (NMR) imaging to capture depth-resolved translational motion of polymer chains in a polytetrafluoroethylene (PTFE) film. By focusing on spin–spin relaxation behavior in amorphous regions near crystalline lamellae, we identify multiple diffusion regimes consistent with Bloch–Torrey analysis. The results reveal that molecular mobility at the substrate interface is significantly constrained, likely due to interfacial pinning, while the air-side surface shows signs of enhanced mobility. Our findings highlight the utility of static-field-gradient NMR for probing nanoscale dynamical heterogeneity in semicrystalline systems.
Received: 15 Oct 2025 – Discussion started: 03 Nov 2025
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Material Science Program, Division of Materials and Environments, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 3768515, Japan
Material Science Program, Division of Materials and Environments, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 3768515, Japan
Teruo Kanki
Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
We developed a new, low-cost nuclear magnetic resonance imaging method to visualize how molecules move inside a solid polymer film. By examining different depths of a poly(tetrafluoroethylene) film, we discovered that molecular motion is strongly limited near the supporting surface but more active at the air side. This finding helps explain how local environments affect the flexibility of polymer materials.
We developed a new, low-cost nuclear magnetic resonance imaging method to visualize how...
