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Title: Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies

Abstract

The structure of layer-by-layer (LbL) deposited nanofilm coatings consists of alternating polyethylenimine (PEI) and polystyrenesulfonate (PSS) films deposited on a single crystal quartz substrate. LbL-deposited nanofilms were investigated by neutron reflectomery (NR) in contact with water in the static and fluid shear stress conditions. The fluid shear stress was applied through a laminar flow of the liquid parallel to the quartz/polymer interface in a custom-built solid–liquid interface cell. The scattering length density profiles obtained from NR results of these polyelectrolyte multilayers (PEM), measured under different shear conditions, showed proportional decrease of volume fraction of water hydrating the polymers. For the highest shear rate applied (ca. 6800 s –1) the water volume fraction decreased by approximately 7%. The decrease of the volume fraction of water was homogeneous through the thickness of the film. Since there were not any significant changes in the total polymer thickness, it resulted in negative osmotic pressures in the film. The PEM films were compared with the behavior of thin films of thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) deposited via spin-coating. The PEM and pNIPAM differ in their interactions with water molecules, and they showed opposite behaviors under the fluid shear stress. In both cases the polymer hydration was reversiblemore » upon the restoration of static conditions. Furthermore, a theoretical explanation is given to explain this difference in the effect of shear on hydration of polymeric thin films.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Vision Care R&D, Alcon, Johns Creek, GA (United States)
  3. Univ. of South Florida, Tampa, FL (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1248638
Report Number(s):
LA-UR-15-20775
Journal ID: ISSN 0743-7463
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 31; Journal Issue: 9; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Singh, Saurabh, Junghans, Ann, Watkins, Erik, Kapoor, Yash, Toomey, Ryan, and Majewski, Jaroslaw. Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies. United States: N. p., 2015. Web. doi:10.1021/acs.langmuir.5b00037.
Singh, Saurabh, Junghans, Ann, Watkins, Erik, Kapoor, Yash, Toomey, Ryan, & Majewski, Jaroslaw. Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies. United States. doi:10.1021/acs.langmuir.5b00037.
Singh, Saurabh, Junghans, Ann, Watkins, Erik, Kapoor, Yash, Toomey, Ryan, and Majewski, Jaroslaw. Tue . "Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies". United States. doi:10.1021/acs.langmuir.5b00037. https://www.osti.gov/servlets/purl/1248638.
@article{osti_1248638,
title = {Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies},
author = {Singh, Saurabh and Junghans, Ann and Watkins, Erik and Kapoor, Yash and Toomey, Ryan and Majewski, Jaroslaw},
abstractNote = {The structure of layer-by-layer (LbL) deposited nanofilm coatings consists of alternating polyethylenimine (PEI) and polystyrenesulfonate (PSS) films deposited on a single crystal quartz substrate. LbL-deposited nanofilms were investigated by neutron reflectomery (NR) in contact with water in the static and fluid shear stress conditions. The fluid shear stress was applied through a laminar flow of the liquid parallel to the quartz/polymer interface in a custom-built solid–liquid interface cell. The scattering length density profiles obtained from NR results of these polyelectrolyte multilayers (PEM), measured under different shear conditions, showed proportional decrease of volume fraction of water hydrating the polymers. For the highest shear rate applied (ca. 6800 s–1) the water volume fraction decreased by approximately 7%. The decrease of the volume fraction of water was homogeneous through the thickness of the film. Since there were not any significant changes in the total polymer thickness, it resulted in negative osmotic pressures in the film. The PEM films were compared with the behavior of thin films of thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) deposited via spin-coating. The PEM and pNIPAM differ in their interactions with water molecules, and they showed opposite behaviors under the fluid shear stress. In both cases the polymer hydration was reversible upon the restoration of static conditions. Furthermore, a theoretical explanation is given to explain this difference in the effect of shear on hydration of polymeric thin films.},
doi = {10.1021/acs.langmuir.5b00037},
journal = {Langmuir},
number = 9,
volume = 31,
place = {United States},
year = {Tue Feb 17 00:00:00 EST 2015},
month = {Tue Feb 17 00:00:00 EST 2015}
}

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