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Open AccessArticle

Thermally Tunable Dynamic and Static Elastic Properties of Hydrogel Due to Volumetric Phase Transition

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Department of Physics, University of North Texas, P.O. Box 311427, Denton, TX 76203, USA
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Department of Mechanical and Energy Engineering, University of North Texas, 3940 North Elm Suite F101, Denton, TX 76207, USA
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Author to whom correspondence should be addressed.
Polymers 2020, 12(7), 1462; https://doi.org/10.3390/polym12071462
Received: 27 May 2020 / Revised: 24 June 2020 / Accepted: 28 June 2020 / Published: 30 June 2020
(This article belongs to the Special Issue Functional, High Modulus Polymer Based Organic/Inorganic Composites)
The temperature dependence of the mechanical properties of polyvinyl alcohol-based poly n-isopropyl acrylamide (PVA-PNIPAm) hydrogel was studied from the static and dynamic bulk modulus of the material. The effect of the temperature-induced volumetric phase transition on Young’s Modulus, Poisson’s ratio, and the density of PVA-PNIPAm was experimentally measured and compared with a non-thermo-responsive Alginate hydrogel as a reference. An increase in the temperature from 27.5 to 32 °C results in the conventional temperature-dependent de-swelling of the PVA-PNIPAm hydrogel volume of up to 70% at the lower critical solution temperature (LCST). However, with the increase in temperature, the PVA-PNIPAm hydrogel showed a drastic increase in Young’s Modulus and density of PVA-PNIPAm and a corresponding decrease in the Poisson’s ratio and the static bulk modulus around the LCST temperature. The dynamic bulk modulus of the PVA-PNIPAm hydrogel is highly frequency-dependent before the LCST and highly temperature-sensitive after the LCST. The dynamic elastic properties of the thermo-responsive PVA-PNIPAm hydrogel were compared and observed to be significantly different from the thermally insensitive Alginate hydrogel. View Full-Text
Keywords: mechanical properties; bulk modulus; density; deswelling ratio; Poisson’s ratio thermo-responsive; gels; polymer hydrogels; temperature sensitive; dynamic elasticity mechanical properties; bulk modulus; density; deswelling ratio; Poisson’s ratio thermo-responsive; gels; polymer hydrogels; temperature sensitive; dynamic elasticity
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MDPI and ACS Style

Jin, Y.; Yang, T.; Ju, S.; Zhang, H.; Choi, T.-Y.; Neogi, A. Thermally Tunable Dynamic and Static Elastic Properties of Hydrogel Due to Volumetric Phase Transition. Polymers 2020, 12, 1462.

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