Design of nonaqueous polymer gels with broad temperature performance: Impact of solvent quality and processing condition
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Phillip J. Colea) Sandia National Laboratories, Albuquerque, New Mexico 87185; and Northrop Grumman A&AS, Arlington, Virginia 22209
Shannon M. Cole, John L. Schroeder, and Duane A. Schneider Sandia National Laboratories, Albuquerque, New Mexico 87185
Ronald C. Hedden Texas Tech University, Department of Chemical Engineering, Lubbock, Texas 79409
Joseph L. Lenhartb) U.S. Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005; and Sandia National Laboratories, Albuquerque, New Mexico 87185 (Received 4 December 2009; accepted 15 March 2010)
Polymer gels have potential use for a wide variety of applications, primarily due to the ability to tailor the gel properties by varying several material parameters. While substantial attention has focused on water-based hydrogels, the use of these materials is limited due to a narrow operational temperature range. This report describes a nonaqueous polymer gel, composed of a cross-linked polybutadiene network swollen with low volatility polymer plasticizers. Thermal, mechanical, and adhesive characterization illustrated that the gels exhibit performance over an extremely broad temperature range (60–70 C). Solvent quality and loading played a critical role in the operational temperature window with small solvent solubility parameter deviations dramatically reducing the operational temperature range. In addition, the processing conditions had a large impact on the gel mechanical properties. As a result, it is important to consider the influence of processing conditions and solvent quality when tailoring polymer gels for practical applications.
I. INTRODUCTION
Polymer gels have received considerable attention for use in a wide range of practical applications as a result of the ability to tailor the electrical, mechanical, and optical properties of the material. Polymer gel properties are typically modified by altering the network polymer chemistry,1 solvent type,2 and solvent loading3 or through the addition of small molecule additives and fillers.4 Polymer and solvent molecular weight and chain architecture may also have an effect. A key to designing a gel material for a specific application is to understand the role of the polymer-solvent interactions on the gel structure and properties.1,2 A significant amount of work has been focused on water-based hydrogels for applications including biomedical technology,5–8 optical mateAddress all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/JMR.2010.0155 J. Mater. Res., Vol. 25, No. 6, Jun 2010
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rials,9 and sensors.10–12 A classic example is a hydrogel based on poly-(N-isopropylacrylamide) (PNIPAM), that exhibits a volume shrinkage transition near 33 C.13 Because of the near room temperature responsiveness of PNIPAM hydrogels, they have been exploited in the biological community for many applications including controlled release,14 cellular adhesion,15 and nucleic acid pur
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