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Title: Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites

Abstract

Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (T g) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this paper, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane SMPs were loaded with either 5 wt % carbon black or 5 wt % carbon nanotubes, and subsequently coated with either an Al 2O 3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37°C) and subsequent T g depression versus uncoated composites. Finally, in turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37°C.

Authors:
 [1];  [1];  [2];  [1]
  1. Texas A&M Univ., College Station, TX (United States). Dept. of Biomedical Engineering
  2. Texas A&M Univ., College Station, TX (United States). Dept. of Biomedical Engineering; Texas A&M Univ., College Station, TX (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Texas A&M Univ., College Station, TX (United States)
Sponsoring Org.:
USDOE; National Institutes of Health (NIH)
OSTI Identifier:
1343094
Grant/Contract Number:
AC52-07NA27344; R01EB000462
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Polymer Science
Additional Journal Information:
Journal Volume: 132; Journal Issue: 1; Journal ID: ISSN 0021-8995
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 59 BASIC BIOLOGICAL SCIENCES; biomedical applications; conducting polymers; thermosets; polyurethanes

Citation Formats

Yu, Ya-Jen, Infanger, Stephen, Grunlan, Melissa A., and Maitland, Duncan J. Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites. United States: N. p., 2014. Web. doi:10.1002/app.41226.
Yu, Ya-Jen, Infanger, Stephen, Grunlan, Melissa A., & Maitland, Duncan J. Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites. United States. doi:10.1002/app.41226.
Yu, Ya-Jen, Infanger, Stephen, Grunlan, Melissa A., and Maitland, Duncan J. Thu . "Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites". United States. doi:10.1002/app.41226. https://www.osti.gov/servlets/purl/1343094.
@article{osti_1343094,
title = {Silicone membranes to inhibit water uptake into thermoset polyurethane shape-memory polymer conductive composites},
author = {Yu, Ya-Jen and Infanger, Stephen and Grunlan, Melissa A. and Maitland, Duncan J.},
abstractNote = {Electroactive shape memory polymer (SMP) composites capable of shape actuation via resistive heating are of interest for various biomedical applications. However, water uptake into SMPs will produce a depression of the glass transition temperature (Tg) resulting in shape recovery in vivo. While water actuated shape recovery may be useful, it is foreseen to be undesirable during early periods of surgical placement into the body. Silicone membranes have been previously reported to prevent release of conductive filler from an electroactive polymer composite in vivo. In this paper, a silicone membrane was used to inhibit water uptake into a thermoset SMP composite containing conductive filler. Thermoset polyurethane SMPs were loaded with either 5 wt % carbon black or 5 wt % carbon nanotubes, and subsequently coated with either an Al2O3- or silica-filled silicone membrane. It was observed that the silicone membranes, particularly the silica-filled membrane, reduced the rate of water absorption (37°C) and subsequent Tg depression versus uncoated composites. Finally, in turn, this led to a reduction in the rate of recovery of the permanent shape when exposed to water at 37°C.},
doi = {10.1002/app.41226},
journal = {Journal of Applied Polymer Science},
number = 1,
volume = 132,
place = {United States},
year = {Thu Jul 24 00:00:00 EDT 2014},
month = {Thu Jul 24 00:00:00 EDT 2014}
}

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Free Publicly Available Full Text
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Cited by: 2works
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  • Water uptake and ionic conductivities are reported for Nafion 115 membranes as functions of water activity and percentage of sulfonic groups occupied by sodium impurities. Water content was determined gravimetrically under liquid hydration and at 100, 75.3, and 11.3% relative humidity (RH). Water content exponentially decreased from the H{sup +}-form membrane water uptake isotherm to the Na{sup +}-form isotherm when hydrated by water vapor. Ninety percent of this decrease is reached at a substitution level of 0.2Na{sup +}/SO{sub 3}{sup -}. Water uptake under liquid water hydration decreased more gradually, only 50% to completion at 0.2Na{sup +}/SO{sub 3}{sup -}. Four-probe conductivitymore » testing of Nafion 115 membranes, normalized against dry dimensions, revealed that although hydration decreases immediately with the introduction of sodium impurities, ionic conductivity at 100% RH remains constant up to 0.15Na{sup +}/SO{sub 3}{sup -}. Above 0.15Na{sup +}/SO{sub 3}{sup -} an exponential decrease in ionic conductivity is observed with higher sodium content. The dependence of ionic conductivity on water content is also reported for sodium contents of 0, 0.27, 0.62 and 1Na{sup +}/SO{sub 3}{sup -}.« less
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  • The impact of dispersed alkylthiol-modified ZnO nanorods, as a function of rod aspect ratio and concentration, on the shape memory character of a thermoplastic polyurethane with low hard-segment density (LHS-TPU) is examined relative to the enhanced performance occurring for carbon nanofiber (CNF) dispersion. Solution blending resulted in uniform dispersion within the LHS-TPU of the ZnO nanorods at low volume (weight) fractions (<2.9% v/v (17.75% w/w)). Tensile modulus enhancements were modest though, comparable to values observed for spherical nanofillers. Shape memory characteristics, which in this LHS-TPU result when strain-induced crystallites retard the entropic recovery of the deformed chains, were unchanged formore » these low volume fraction ZnO nanocomposites. Higher ZnO loadings (12% v/v (50% w/w)) exhibited clustering of ZnO nanorods into a mesh-like structure. Here, tensile modulus and shape recovery characteristics were improved, although not as great as seen for comparable CNF addition. Wide angle X-ray diffraction and NMR revealed that the addition of ZnO nanorods did not impact the inherent strain induced crystallization of the LHS-TPU, which is in contrast to the impact of CNFs and emphasizes the impact of interactions at the polymer-nanoparticle interface. Overall, these findings reinforce the hypothesis that the shape memory properties of polymer nanocomposites are governed by the extent to which nanoparticle addition, via nanoparticle aspect ratio, hierarchical morphology, and interfacial interactions, impacts the molecular mechanism responsible for trapping elastic strain.« less