Dynamic light scattering, potentiometric titration, transmission electron microscopy and atomic force microscopy have been used to investigate the micellar behaviour and metal-nanoparticle formation in poly(ethylene oxide)-block-poly(2-vinylpyridine), PEO-b-P2VP, poly(hexa(ethylene glycol) methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate), PHEGMA-b-PDEAEMA, and PEO-b-PDEAEMA amphiphilic diblock copolymers in water. The hydrophobic block of these copolymers (P2VP or PDEAEMA) is pH-sensitive: at low pH it can be protonated and becomes partially or completely hydrophilic leading to molecular solubility whereas at higher pH micelles are formed. These micelles consist of a P2VP or PDEAEMA core and a PEO or PHEGMA corona, respectively, where the core forming amine units can incorporate metal compounds due to coordination. The metal compounds (e.g., H2PtCl6, K2PtCl6) can either be introduced in a micellar solution, where they are incorporated within the micelle core via coordination with functional groups, or can be added to a unimer solution at low pH, where they lead to a metal-induced micellization. In these micellar nanoreactors, metal nanoparticles nucleate and grow upon reduction with sizes in the range of a few nanometers as observed by TEM. The effect of the metal incorporation method on the characteristics of the micelles and of the synthesized nanoparticles is investigated.

The primary challenge regarding solid polymer electrolytes (SPEs) is the development of materials with enhanced mechanical modulus without sacrificing ionic conductivity. Here, we demonstrate that when stiff/rigid polymer nanoparticles that are thermodynamically miscible with a polymer are utilized in a blend with a liquid electrolyte, the elastic modulus and the ionic conductivity of the resulting SPEs increase compared to the linear polymer blend analogues. In particular, when poly­(methyl methacrylate), PMMA, nanoparticles, composed of high functionality star-shaped PMMA, were added to low molecular weight poly­(ethylene oxide), PEO, doped with bis­(trifluoromethane)­sulfonamide (LiTFSI), the resulting SPEs exhibit 2 orders of magnitude higher conductivity and 1 order of magnitude higher mechanical strength compared to their linear PMMA blend analogues. In addition, the former remain solidlike over an extended temperature range. Key to their performance is the morphology that stems from the ability of the PMMA nanoparticles to disperse within the liquid electrolyte host, allowing for the formation of a highly interconnected network of pure liquid electrolyte that leads to high ionic conductivity (comparable to that of the neat PEO electrolyte). The present strategy offers tremendous potential for the design of all-polymer electrolytes with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced electrochemical devices.

For the next generation of safe and high energy rechargeable lithium metal batteries, we introduce nanostructured polymer particles of asymmetric miktoarm star copolymers as additives to liquid electrolytes for use as solid polymer electrolytes (SPE). The mechanical properties of the resulting SPEs are dramatically improved compared to the pure liquid electrolyte (the elastic modulus increased by up to 8 orders of magnitude), while the ionic conductivity was maintained close to that of the pure liquid electrolyte. In particular, the addition of 44 wt % miktoarm stars, composed of ion conducting poly­(ethylene oxide), PEO, arms that complement stiff insulating polystyrene arms, PS ((PS) n (PEO) n , where n = 30 the number of arms), in a low molecular weight PEO doped with lithium bis­(trifluoro­methane)­sulfonamide (LiTFSI), resulted in SPEs with a shear modulus of G′ ∼ 0.1 GPa and ion conductivity σ ∼ 10–4 S/cm. The SPEs show a strong decoupling between the mechanical behavior and the ionic conductivity as G′ remains fairly constant for temperatures up to the glass transition temperature of the PS blocks, while the conductivity monotonically increases reaching σ ∼ 10–2 S/cm. Our strategy offers tremendous potential for the design of all-polymer nanostructured materials with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced lithium battery technology.