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Title: Microphase-Separated Morphologies and Molecular Network Topologies in Multiblock Copolymer Gels

Abstract

Strong physical gels derived from thermoplastic elastomeric ABA triblock copolymers solvated with a midblock-selective oil continue to find use in increasingly diverse applications requiring highly elastic and mechanically robust soft materials with tunable properties. Here, in this study, we first investigate the morphological characteristics of thermoplastic elastomer gels (TPEGs) derived from a homologous series of linear A(BA) n multiblock copolymers composed of styrene and hydrogenated isoprene repeat units and possessing comparable molecular weight but varying in the number of B-blocks: 1 (triblock), 2 (pentablock), and 3 (heptablock). Small-angle X-ray scattering performed at ambient temperature confirms that (i) increasing hydrogenation reduces the microdomain periodicity of the neat copolymers and (ii) increasing the oil concentration of the TPEGs tends to swell the nanostructure (increasing the periodicity), but concurrently decreases the size of the styrenic micelles, to different extents depending on the molecular architecture. Complementary dissipative particle dynamics simulations reveal the level to which midblock bridging, which is primarily responsible for the elasticity in this class of materials, is influenced by both oil concentration and molecular architecture. Since constrained topological complexity increases with increasing block number, we introduce a midblock conformation index that facilitates systematic classification of the different topologies involved in nearest-micellemore » bridge formation. Lastly, those possessing at least one bridged and one looped midblock with no dangling ends are found to be the most predominant topologies in the pentablock and heptablock networks.« less

Authors:
 [1];  [2];  [3];  [4]; ORCiD logo [5];  [3];  [6]; ORCiD logo [7]
  1. North Carolina State Univ., Raleigh, NC (United States). Department of Chemical & Biomolecular Engineering
  2. North Carolina State Univ., Raleigh, NC (United States). Department of Materials Science & Engineering
  3. The Procter & Gamble Company, Cincinnati, OH (United States). Corporate Research & Development
  4. Imperial College, London (United Kingdom). Department of Materials
  5. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  6. North Carolina State Univ., Raleigh, NC (United States). Fiber & Polymer Science Program
  7. North Carolina State Univ., Raleigh, NC (United States). Department of Chemical & Biomolecular Engineering and Department of Materials Science & Engineering ; Humboldt-Universität zu Berlin, Berlin (Germany). IRIS Adlershof
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Nonwovens Institute (NWI); German Research Foundation (DFG)
OSTI Identifier:
1465729
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 51; Journal Issue: 14; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Tuhin, Mohammad O., Ryan, Justin J., Sadler, J. David, Han, Zexiang, Lee, Byeongdu, Smith, Steven D., Pasquinelli, Melissa A., and Spontak, Richard J. Microphase-Separated Morphologies and Molecular Network Topologies in Multiblock Copolymer Gels. United States: N. p., 2018. Web. doi:10.1021/acs.macromol.8b00853.
Tuhin, Mohammad O., Ryan, Justin J., Sadler, J. David, Han, Zexiang, Lee, Byeongdu, Smith, Steven D., Pasquinelli, Melissa A., & Spontak, Richard J. Microphase-Separated Morphologies and Molecular Network Topologies in Multiblock Copolymer Gels. United States. doi:10.1021/acs.macromol.8b00853.
Tuhin, Mohammad O., Ryan, Justin J., Sadler, J. David, Han, Zexiang, Lee, Byeongdu, Smith, Steven D., Pasquinelli, Melissa A., and Spontak, Richard J. Fri . "Microphase-Separated Morphologies and Molecular Network Topologies in Multiblock Copolymer Gels". United States. doi:10.1021/acs.macromol.8b00853. https://www.osti.gov/servlets/purl/1465729.
@article{osti_1465729,
title = {Microphase-Separated Morphologies and Molecular Network Topologies in Multiblock Copolymer Gels},
author = {Tuhin, Mohammad O. and Ryan, Justin J. and Sadler, J. David and Han, Zexiang and Lee, Byeongdu and Smith, Steven D. and Pasquinelli, Melissa A. and Spontak, Richard J.},
abstractNote = {Strong physical gels derived from thermoplastic elastomeric ABA triblock copolymers solvated with a midblock-selective oil continue to find use in increasingly diverse applications requiring highly elastic and mechanically robust soft materials with tunable properties. Here, in this study, we first investigate the morphological characteristics of thermoplastic elastomer gels (TPEGs) derived from a homologous series of linear A(BA)n multiblock copolymers composed of styrene and hydrogenated isoprene repeat units and possessing comparable molecular weight but varying in the number of B-blocks: 1 (triblock), 2 (pentablock), and 3 (heptablock). Small-angle X-ray scattering performed at ambient temperature confirms that (i) increasing hydrogenation reduces the microdomain periodicity of the neat copolymers and (ii) increasing the oil concentration of the TPEGs tends to swell the nanostructure (increasing the periodicity), but concurrently decreases the size of the styrenic micelles, to different extents depending on the molecular architecture. Complementary dissipative particle dynamics simulations reveal the level to which midblock bridging, which is primarily responsible for the elasticity in this class of materials, is influenced by both oil concentration and molecular architecture. Since constrained topological complexity increases with increasing block number, we introduce a midblock conformation index that facilitates systematic classification of the different topologies involved in nearest-micelle bridge formation. Lastly, those possessing at least one bridged and one looped midblock with no dangling ends are found to be the most predominant topologies in the pentablock and heptablock networks.},
doi = {10.1021/acs.macromol.8b00853},
journal = {Macromolecules},
issn = {0024-9297},
number = 14,
volume = 51,
place = {United States},
year = {2018},
month = {7}
}

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