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Title: Influence of Hydrophobicity on Polyelectrolyte Complexation

Polyelectrolyte complexes are a fascinating class of soft materials that can span the full spectrum of mechanical properties from low-viscosity fluids to glassy solids. This spectrum can be accessed by modulating the extent of electrostatic association in these complexes. However, to realize the full potential of polyelectrolyte complexes as functional materials, their molecular level details need to be clearly correlated with their mechanical response. The present work demonstrates that by making simple amendments to the chain architecture, it is possible to affect the salt responsiveness of polyelectrolyte complexes in a systematic manner. This is achieved by quaternizing poly(4-vinylpyridine) (QVP) with methyl, ethyl, and propyl substituents—thereby increasing the hydrophobicity with increasing side chain length—and complexing them with a common anionic polyelectrolyte, poly(styrenesulfonate). The mechanical behavior of these complexes is compared to the more hydrophilic system of poly(styrenesulfonate) and poly(diallyldimethylammonium) by quantifying the swelling behavior in response to salt stimuli. More hydrophobic complexes are found to be more resistant to doping by salt, yet the mechanical properties of the complex remain contingent on the overall swelling ratio of the complex itself, following near universal swelling–modulus master curves that are quantified in this work. Furthermore, the rheological behaviors of QVP complex coacervates aremore » found to be approximately the same, only requiring higher salt concentrations to overcome strong hydrophobic interactions, demonstrating that hydrophobicity can be used as an important parameter for tuning the stability of polyelectrolyte complexes in general, while still preserving the ability to be processed “saloplastically”.« less
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  1. Northwestern Univ., Evanston, IL (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 50; Journal Issue: 23; Journal ID: ISSN 0024-9297
American Chemical Society
Research Org:
Northwestern Univ., Evanston, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Institute of Standards and Technology (NIST); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institute of Standards and Technology (NIST).Center for Hierarchical Materials Design (CHiMaD)
Country of Publication:
United States
36 MATERIALS SCIENCE; polyelectrolyte; complexation; rheology; hydrophobicity
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1421981