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Title: Characterization of Free Surface-Bound and Entrapped Water Environments in Poly(N-Isopropyl Acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy

Abstract

We found that different water environments in poly(N-isopropyl acrylamide) (PNIPAAm) hydrogels are identified and characterized using 1H high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR). Local water environments corresponding to a “free” highly mobile species, along with waters showing restricted dynamics are resolved in these swollen hydro-gels. For photo-initiated polymerized PNIPAAm gels, an additional entrapped water species is observed. Spin–spin R2 relaxation experiments support the argument of reduced mobility in the restricted and entrapped water species. Furthermore, by combining pulse field gradient techniques with HRMAS NMR it is possible to directly measure the self-diffusion rate for these different water environments. The behavior of the heterogeneous water environments through the lower critical solution temperature transition is described.

Authors:
 [1];  [1];  [2];  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Univ. of Oklahoma, Norman, OK (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
National Science Foundation (NSF), Arlington, VA (United States)
OSTI Identifier:
1183005
Report Number(s):
SAND-2014-15247J
Journal ID: ISSN 0887-6266; 534159
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Polymer Science. Part B, Polymer Physics
Additional Journal Information:
Journal Volume: 52; Journal Issue: 23; Journal ID: ISSN 0887-6266
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; diffusion; HRMAS; hydrogels; NMR; PFG; stimuli-sensitive polymers; thermoresponsive polymer; water

Citation Formats

Alam, Todd Michael, Childress, Kimberly Kay, Pastoor, Kevin, and Rice, Charles. Characterization of Free Surface-Bound and Entrapped Water Environments in Poly(N-Isopropyl Acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy. United States: N. p., 2014. Web. doi:10.1002/polb.23591.
Alam, Todd Michael, Childress, Kimberly Kay, Pastoor, Kevin, & Rice, Charles. Characterization of Free Surface-Bound and Entrapped Water Environments in Poly(N-Isopropyl Acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy. United States. https://doi.org/10.1002/polb.23591
Alam, Todd Michael, Childress, Kimberly Kay, Pastoor, Kevin, and Rice, Charles. 2014. "Characterization of Free Surface-Bound and Entrapped Water Environments in Poly(N-Isopropyl Acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy". United States. https://doi.org/10.1002/polb.23591. https://www.osti.gov/servlets/purl/1183005.
@article{osti_1183005,
title = {Characterization of Free Surface-Bound and Entrapped Water Environments in Poly(N-Isopropyl Acrylamide) Hydrogels via 1H HRMAS PFG NMR Spectroscopy},
author = {Alam, Todd Michael and Childress, Kimberly Kay and Pastoor, Kevin and Rice, Charles},
abstractNote = {We found that different water environments in poly(N-isopropyl acrylamide) (PNIPAAm) hydrogels are identified and characterized using 1H high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR). Local water environments corresponding to a “free” highly mobile species, along with waters showing restricted dynamics are resolved in these swollen hydro-gels. For photo-initiated polymerized PNIPAAm gels, an additional entrapped water species is observed. Spin–spin R2 relaxation experiments support the argument of reduced mobility in the restricted and entrapped water species. Furthermore, by combining pulse field gradient techniques with HRMAS NMR it is possible to directly measure the self-diffusion rate for these different water environments. The behavior of the heterogeneous water environments through the lower critical solution temperature transition is described.},
doi = {10.1002/polb.23591},
url = {https://www.osti.gov/biblio/1183005}, journal = {Journal of Polymer Science. Part B, Polymer Physics},
issn = {0887-6266},
number = 23,
volume = 52,
place = {United States},
year = {Fri Sep 19 00:00:00 EDT 2014},
month = {Fri Sep 19 00:00:00 EDT 2014}
}

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Cited by: 23 works
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