Nature constitutes an endless source of inspiration for materials scientists and holds solutions for the design and precise macromolecular engineering of functional soft matter 2.0, even (more) a century after the seminal work of Prof. Hermann Staudinger. Striving for a successful encoding of functions (e.g. efficient and/or selective dimensionality-controlled ion/proton transfers) into self-assembled and hierarchized functional soft-matter (e.g., for energy generation and storage) requires i) deeper understanding and ii) mastering the appropriate (but yet very) delicate balances existing in between micro/nano-phase segregation processes and non-covalent interactions at work across many length scales in between chemically incompatible but linked sub-blocks within (multi-block) macromolecular architectures. Based on selected examples from the recent literature and our recent (i.e., during the past 5 years) efforts to enable precise macromolecular engineering towards smart functions, I will present advanced covalent vs. supramolecular (and combined) strategies towards next generation of ionically conducting soft materials for energy-related (nano-ionics/fluidics) smart organic electrolytes for i) Proton-Exchange Membranes Fuel Cells (PEMFCs)) and ii) Lithium-ion/Metal Batteries (LiBs/LMBs).
For the former topic and illustrating reflections on chain microstructure, I will discuss how well-controlled chain folding in precise sulfonated PolyEthylene (PE) can lead to highly uniform hydrated acid layers (of sub-nanometer thickness) with high proton conductivity, on par with the one of the Nafion 117®, a golden standard for proton-exchange membranes. As simple as this idea is, it represents a radical paradigm shift with respect to nearly 5 decades of macromolecular and structural engineering strategies developed around the synthesis and multi-scale structure/proton transport property correlations within PerFluoroSulfonic Acid (PFSA)-based materials. Implementing Nature’ lessons into a synthetic material, the linear PE backbone contains sulfonic acid group pendants precisely organized every twenty-first carbon atom that induce tight chain folds to form the hydrated layers, while the methylene segments crystallize. This layered PE-based structure is an innovative and versatile model-system for functional polymer membranes, opening doors to efficient and selective transport of other ions and small molecules on appropriate selection of functional groups.
For the latter subject and emphasizing onto the (critical) importance of polymer chain end(s), I will discuss the design, synthesis & multi-scale structure/ionic conductivity correlations for novel classes of Mono-End-Capped-Single Ion Polymer Electrolytes (MEC-SIPEs) within the context of state-of-the-art Solid Polymer Electrolytes (SPEs) based on PEO (and beyond). Highlighting the impact of our smart macromolecular design, their chemical, electrochemical (CV, LTN, GCPL), physical (ionic conductivity), and thermal (DSC) characterizations will be presented; their performances being benchmarked with respect to PEO-based (salt-in-polymer and single-ion polymer) electrolytes. Finally, we will exemplify how combining an aromatic moiety acting as a Structure-Directing Group (SDG) and salt moieties at either of, or at both possible sites opens door to improving the Li+ conductivity of PEO electrolytes up to 0.1 mS/cm @ 40°C through this MEC-SIPE blueprint.
Dr. Patrice Rannou (ORCID ID: 0000-0001-9376-7136) graduated from the Textile & Chemical Institute of Lyon (1993/M.Sc. in Polymer Chemistry) and from University Montpellier II (1994/M.Sc. in Polymer Physics) and E.N.S. de Chimie de Montpellier (1994/M.Sc. in Polymer Science). He holds a PhD in Physics from the University J. Fourier (1998) and a research habilitation (HDR) in Chemistry (2013) from the University of Grenoble. After 15 months spent as a visiting researcher at the R & D New Materials Center of Hitachi Chemical Co. Ltd (HCC) in Hitachi-city, Japan, he was hired in 1999 as a CNRS researcher in the UMR5819-SyMMES (Molecular Systems & nanoMaterialS for Energy & health) lab where he is serving (since 2015) as a CNRS Director of Research. Till date (i.e., April 2021), he has (co)advised 15 postdoctoral fellows, (co)supervised 11 PhD students and >35 (under)graduate students. He is the (co)authors of 132 papers (75 regular articles and 57 proceeding papers), 2 book chapters, and 16 patents.