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Static and Dynamic Solution Behavior of a Polyzwitterion Using a Hofmeister Salt Series

Title: Static and Dynamic Solution Behavior of a Polyzwitterion Using a Hofmeister Salt Series.
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Name(s): Delgado, Jose D., author
Schlenoff, Joseph, author
Type of Resource: text
Genre: Text
Journal Article
Date Issued: 2017-05-25
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Polymers made from zwitterionic repeat units (bearing no net charge) have intriguing solution properties, especially in contrast to polyelectrolytes, such as an apparent indifference to salt concentration. These polyzwitterions, PZs, have come under renewed scrutiny because of their use in high performance antifouling coatings. Here, an amidosulfobetaine polymer was used to shed light on the complex and poorly-understood response of PZ solution conformation to ionic strength. A Hofmeister anion series NaX, where X = SO4 2, Cl-, Br-, NO3-, ClO4- and SCN provided a systematic way to tune PZ/ion interactions. A consistent picture of PZ conformation emerged, where the role and location of counterions (how they pair with the polymer chain) depends on their position in the Hofmeister series. At least four regimes of PZ conformation/interaction as a function of ionic strength were observed, the last showing no change in coil size (hydrodynamic radius) as a function of ionic strength for all salts in the concentration range 0.6 M – 4 M. Hydrophobic (less hydrated) anions ClO4- and SCN yielded a clear minimum in coil size at lower [NaX] whereas PZ in solutions of hydrophilic ions SO4- and Cl showed only a hint of the much-discussed “antipolyelectrolyte” expansion of PZ with increasing [NaX]. Static light scattering results, when analyzed using Stockmeyer’s theory of scattering from multicomponent systems, revealed that NaX is associated with PZ with a corresponding increase in apparent molecular weight. Light scattering measurements at low [NaX] show solution ions are excluded from PZ coils dressed with hydrophobic NaX. DLS in salt-free solutions at elevated temperatures revealed substantial chain stiffening of PZ, thought to be caused by nearest-neighbor interactions between zwitterion groups. DLS yielded a fast mode in these salt free solutions, ascribed to soliton-like transport of waves of associated zwitterionic groups along the PZ backbone.
Identifier: FSU_libsubv1_scholarship_submission_1540240683_30337f56 (IID), 10.1021/acs.macromol.7b00525 (DOI)
Publication Note: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.macromol.7b00525.
Grant Number: DMR1506824 (NSF)
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_libsubv1_scholarship_submission_1540240683_30337f56
Owner Institution: FSU
Is Part Of: Macromolecules.

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Delgado, J. D., & Schlenoff, J. (2017). Static and Dynamic Solution Behavior of a Polyzwitterion Using a Hofmeister Salt Series. Macromolecules. Retrieved from http://purl.flvc.org/fsu/fd/FSU_libsubv1_scholarship_submission_1540240683_30337f56