Phase Behavior of Mixtures of Block Copolymers and a Lithium Salt

Loo, Whitney S.; Galluzzo, Michael D.; Li, Xiuhong; Maslyn, Jacqueline A.; Oh, Hee Jeung; Mongcopa, Katrina Irene S.; Zhu, Chenhui; Wang, Andrew A.; Wang, Xin; Garetz, Bruce A.; Balsara, Nitash P.

doi:10.1021/acs.jpcb.8b04189

Cited by 63 publications

(128 citation statements)

References 56 publications

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“…It is well known that the salt selectively partitions into the PEO domain due to specific interactions between ether oxygens and Li + ions and the relatively high dielectric constant of PEO . Table shows the molecular weights, chain lengths and compositions of the materials considered in this study as well as the salt species used for the electrolytes, taken from refs . Included in this list are a PEO homopolymer, a PS homopolymer and 22 SEO block copolymers.…”

Section: Experimental Systemsmentioning

confidence: 99%

“…Gunkel et al and Wanakule et al mapped the phase boundary in a set of salt‐containing SEO copolymers, and the order–disorder transition temperatures ( T ODT ) obtained ranged from 95 to 240°C shown in Figure (yellow squares). Loo et al used the same approach but their data were obtained at a fixed temperature of 100°C. In this study, an increase in salt concentration induced the disorder‐to‐order transition; therefore, the error bars on the data set represent the step change in salt concentration that led to order formation.…”

Section: Flory–huggins Interaction Parameter χmentioning

confidence: 99%

“…These data are also shown in Figure (blue circles). The dashed line in Figure represents an expression for χ eff reported in reference :

χ_{eff} = χ_{0} + 1.66 r

…”

Section: Flory–huggins Interaction Parameter χmentioning

confidence: 99%

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Organizing thermodynamic data obtained from multicomponent polymer electrolytes: Salt‐containing polymer blends and block copolymers

Loo

Balsara

2019

J Polym Sci B Polym Phys

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The objective of this review is to organize literature data on the thermodynamic properties of salt-containing polystyrene/poly(ethylene oxide) (PS/PEO) blends and polystyrene-b-poly (ethylene oxide) (SEO) diblock copolymers. These systems are of interest due to their potential to serve as electrolytes in all-solid rechargeable lithium batteries. Mean-field theories, developed for pure polymer blends and block copolymers, are used to describe phenomenon seen in salt-containing systems. An effective Flory-Huggins interaction parameter, χ eff , that increases linearly with salt concentration is used to describe the effect of salt addition for both blends and block copolymers. Segregation strength, χ eff N, where N is the chain length of the homopolymers or block copolymers, is used to map phase behavior of salty systems as a function of composition. Domain spacing of salt-containing block copolymers is normalized to account for the effect of copolymer composition using an expression obtained in the weak segregation limit. The phase behavior of salty blends, salty block copolymers, and domain spacings of the latter systems, are presented as a function of chain length, composition and salt concentration on universal plots. While the proposed framework has limitations, the universal plots should serve as a starting point for organizing data from other salt-containing polymer mixtures.

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Section: Experimental Systemsmentioning

confidence: 99%

Section: Flory–huggins Interaction Parameter χmentioning

confidence: 99%

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Organizing thermodynamic data obtained from multicomponent polymer electrolytes: Salt‐containing polymer blends and block copolymers

Loo

Balsara

2019

J Polym Sci B Polym Phys

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“…In Fig. 1, we present schematics of the experimentally observed morphologies of a polystyrene-block-poly(ethylene oxide) (SEO) electrolyte as a function of composition [27][28][29] . We use the volume fraction of the conducting domain (i.e.…”

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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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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“…This form for χ eff in salty systems was first proposed in the pioneering work of Mayes and coworkers. 34 In this paper, which builds on our previous study of the phase behavior of block copolymer electrolytes 35 increases with added salt and m is negative. We find that m is a smooth function of f EO .…”

Section: Introductionmentioning

confidence: 86%

Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point

et al. 2019

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The thermodynamics of block copolymer/salt mixtures were quantified through the application of Leibler's Random Phase Approximation to disordered small angle X-ray scattering profiles. The experimental system comprises of polystyrene-block-poly(ethylene oxide) (SEO) mixed with lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI), SEO/LiTFSI. The Flory-Huggins interaction parameter determined from scattering experiments, χ SC , was found to be a function of block copolymer composition, chain length, and temperature for both salt-free and salty systems. In the absence of salt, χ 0 , SC is a linear function of (N f EO) −1 ; in the presence of salt, a linear approximation is used to describe the effect of salt on χ eff ,SC for a given copolymer composition and chain length. The theory of Sanchez was used to determine χ eff from χ eff ,SC in order to predict the boundary between order and disorder as a function of chain length, block copolymer composition, salt concentration, and temperature. At fixed temperature (100 o C), N crit , the chain length of SEO at the order-disorder transition in SEO/LiTFSI mixtures, was predicted as a function of the volume fraction of the salt-containing poly(ethylene oxide)-rich microphase, f EO , salt , and salt concentration. At f EO , salt >0.27, the addition of salt stabilizes the ordered phase; at f EO ,salt <0.27, the addition of salt stabilizes the disordered phase. We propose a simple theoretical model to predict the block copolymer 3 composition at which phase behavior is independent of salt concentration (f EO , salt =0.27). We refer to this composition as the "isotaksis point".

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Phase Behavior of Mixtures of Block Copolymers and a Lithium Salt

Cited by 63 publications

References 56 publications

Organizing thermodynamic data obtained from multicomponent polymer electrolytes: Salt‐containing polymer blends and block copolymers

Organizing thermodynamic data obtained from multicomponent polymer electrolytes: Salt‐containing polymer blends and block copolymers

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

Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point

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