Diffusion in Lamellae, Cylinders, and Double Gyroid Block Copolymer Nanostructures

The design and engineering of composite materials is one strategy to satisfy the materials needs of systems with multiple orthogonal property requirements. In the case of rechargeable batteries with lithium metal anodes, the system requires a separator with fast lithium ion transport and good mechanical strength. In this work, we focus on the system polystyrene-blockpoly(ethylene oxide) (SEO) with bis(trifluoromethane)sulfonimide lithium salt (LiTFSI). Ion transport occurs in the salt-containing poly(ethylene oxide)-rich domains. Mechanical rigidity arises due to the glassy nature of polystyrene (PS). If we assume that the salt does not interact with the PS-rich domains, we can describe ion transport in the electrolyte by three transport parameters (ionic conductivity, , salt diffusion coefficient, , and cation transference number, + 0) and a thermodynamic factor, f. By systematically varying the volume fraction of the conducting phase, c between 0.29 and 1.0, and chain length, between 80 and 8000, we elucidate the role of morphology on ion transport. We find that is the strongest function of morphology, varying by three full orders of magnitude, while is a weaker function of morphology. To calculate + 0 and f , we measure the current fraction, + , and the open circuit potential, , of concentration cells. We find that + and follow universal trends as a function of salt concentration, regardless of chain length, morphology, or c , allowing us to calculate + 0 for any SEO/LiTFSI or PEO/LiTFSI mixture when and are known. The framework developed in this paper enables predicting the performance of any block copolymer electrolyte in a rechargeable battery. MAIN TEXT

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“…BCC', HEX', GYR'), we assume that = 1. The numerical values of and reported in Table II are taken from refs 30,65 .…”

Section: Resultsmentioning

confidence: 99%

“…GYR, LAM, and GYR'). Recent computational studies by Shen, Brown, and Hall have shown that the lamellar morphology is optimal for ion diffusion 30 . The purpose of this paper is to experimentally characterize ion transport through different morphologies.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Three Transport Coefficients and the Thermodynamic Factor in Block Copolymer Electrolytes with Different Morphologies

et al. 2020

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“…One mechanism for forming physically crosslinked organogels is employment of an ABA triblock copolymer and a midblock selective solvent. This combination drives self‐assembly via microphase separation of the copolymer endblocks resulting in distinct endblock domains of various sizes and geometries depending on the polymer concentration and block composition 19–23 . Furthermore, the ABA copolymer architecture necessitates that midblocks are tethered to endblock domains at both termini.…”

Section: Introductionmentioning

confidence: 99%

Effect of network connectivity on the mechanical and transport properties of block copolymer gels

Rankin

Lee

Mineart

2020

Journal of Polymer Science

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Establishing the independent tunability of transport and mechanical properties in polymer gels would significantly contribute to their implementation as transdermal drug delivery media, among other things. The work conducted herein uses facile changes in the formulation of physically crosslinked styrenic ABA/AB block copolymer organogels to alter their mechanical properties independently from the mass transport of an internally-loaded nanocarrier. Such independent tunability is made possible by altering the relative amounts of ABA triblock and AB diblock copolymers while holding total copolymer concentration fixed. Specifically, three series of gels each with a fixed total copolymer concentration (10, 20, or 30 wt%) comprised of varying triblock copolymer concentration are studied. Small angle x-ray scattering confirms that, at the nanoscale, only gel network connectivity changes within each series, while mechanical and release experiments show that increasing network connectivity leads to significant growth of gel moduli, but little change in nanocarrier release rate.

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“…[3][4][5] Theoretical simulations and experimental results demonstrated that ion conductivity of nanostructured block copolymer electrolytes highly depends on ionic domain continuity and orientations across grain boundaries. [6][7][8][9][10] Among diverse morphologies, the double gyroid phases and inverse hexagonal cylinders with ion-conductive domains as the matrix as proton-conducting channels. [41] Our group utilized POMs as electrostatic crosslinkers to access bicontinuous nanocomposites with enhanced proton conductivity and modulus from lamellar poly(styrene-block-2-vinylpyridine) (PS-b-P2VP).…”

Section: The Primary Issue Of Polymer Electrolytes Is To Achieve Highmentioning

confidence: 99%

Triblock Copolymer/Polyoxometalate Nanocomposite Electrolytes with Inverse Hexagonal Cylindrical Nanostructures

Zhai

Chai

Wang

et al. 2020

Macromol. Rapid Commun.

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The primary issue of polymer electrolytes is to achieve high ion conductivity while retaining mechanical properties. A nanocomposite electrolyte with the inverse hexagonal cylindrical phase (three‐dimensionally continuous domains for ion conduction and embedded domains for mechanical support) is prepared through the electrostatic self‐assembly of a polyoxometalate (H3PW12O40, PW) and a triblock copolymer poly(N‐vinyl pyrrolidone)‐block‐polystyrene‐block‐poly(N‐vinyl pyrrolidone) (PSP). The cylindrical nanocomposite exhibits a conductivity of 1.32 mS cm−1 and a storage modulus of 4.6 × 107 Pa at room temperature. These two values are higher than those of pristine PSP by two orders of magnitudes and a factor of six, respectively. PW clusters are used as multifunctional nano‐additives (morphological inducer, proton conductor, and nano‐enhancer) and their incorporation achieves the simultaneous improvement in both conductive and mechanical performance.

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Diffusion in Lamellae, Cylinders, and Double Gyroid Block Copolymer Nanostructures

Cited by 77 publications

References 82 publications

Measurement of Three Transport Coefficients and the Thermodynamic Factor in Block Copolymer Electrolytes with Different Morphologies

Measurement of Three Transport Coefficients and the Thermodynamic Factor in Block Copolymer Electrolytes with Different Morphologies

Effect of network connectivity on the mechanical and transport properties of block copolymer gels

Triblock Copolymer/Polyoxometalate Nanocomposite Electrolytes with Inverse Hexagonal Cylindrical Nanostructures

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