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

Abstract

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 is comprised 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 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 °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 composition at which phase behavior is independent of salt concentration ($$f_{EO,salt,}$$ = 0.27). Here, we refer to this composition as the “isotaksis point”.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1];  [1]; ORCiD logo [3]
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint Center for Energy Storage Research
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
1605253
Grant/Contract Number:  
AC02-05CH11231; AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 52; Journal Issue: 15; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Loo, Whitney S., Sethi, Gurmukh K., Teran, Alexander A., Galluzzo, Michael D., Maslyn, Jacqueline A., Oh, Hee Jeung, Mongcopa, Katrina I., and Balsara, Nitash P. Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point. United States: N. p., 2019. Web. doi:10.1021/acs.macromol.9b00884.
Loo, Whitney S., Sethi, Gurmukh K., Teran, Alexander A., Galluzzo, Michael D., Maslyn, Jacqueline A., Oh, Hee Jeung, Mongcopa, Katrina I., & Balsara, Nitash P. Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point. United States. doi:10.1021/acs.macromol.9b00884.
Loo, Whitney S., Sethi, Gurmukh K., Teran, Alexander A., Galluzzo, Michael D., Maslyn, Jacqueline A., Oh, Hee Jeung, Mongcopa, Katrina I., and Balsara, Nitash P. Thu . "Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point". United States. doi:10.1021/acs.macromol.9b00884. https://www.osti.gov/servlets/purl/1605253.
@article{osti_1605253,
title = {Composition Dependence of the Flory–Huggins Interaction Parameters of Block Copolymer Electrolytes and the Isotaksis Point},
author = {Loo, Whitney S. and Sethi, Gurmukh K. and Teran, Alexander A. and Galluzzo, Michael D. and Maslyn, Jacqueline A. and Oh, Hee Jeung and Mongcopa, Katrina I. and Balsara, Nitash P.},
abstractNote = {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 is comprised 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, χSC, 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, χ0,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 χeff,SC for a given copolymer composition and chain length. The theory of Sanchez was used to determine χeff from χeff,SC 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 °C), Ncrit, 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 composition at which phase behavior is independent of salt concentration ($f_{EO,salt,}$ = 0.27). Here, we refer to this composition as the “isotaksis point”.},
doi = {10.1021/acs.macromol.9b00884},
journal = {Macromolecules},
issn = {0024-9297},
number = 15,
volume = 52,
place = {United States},
year = {2019},
month = {7}
}

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