msepostdoc-list Seminar Notice for Travis Thornell's Ph.D. Final Exam. Seminar: Tuesday, April 17, at 9:30 a.m., in ARMS 1028: Exam same day at 10:30, in ARMS 2237

[Son, Rosemary E]

Please consider attending the following:

MATERIALS ENGINEERING
SEMINAR


"Synthesis and Characterization of Model Acrylic-based Polymer Gels."


By
Travis L. Thornell
Purdue MSE Ph.D. Final Exam

Advisor: Professor Kendra A. Erk


ABSTRACT


Materials made from polymer gel networks are important to many everyday applications in health care to building materials. These gel materials can be easily synthesized in various ways, but characterizing the overall material mechanics and properties are challenging due to the soft nature of their respective bulk structures. Model acrylic-based copolymer gels were investigated to understand the fundamental characteristics and mechanical properties from different crosslinking and gelation processes.
First, model hydrogels with fracture-healing characteristics similar to materials needed for injectable drug delivery systems were studied using shear rheology to determine timescales of fully healed networks.  The industrially available gel was a thermoreversible triblock copolymer composed of poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate) in 2-ethyl hexanol to form a physical gel from polymer-solvent interactions. A methodology of quantifying healing was developed from an applied constant shear rate and monitoring the shear stress response of the samples. The maximum shear stress responses observed during fracture and re-fracture after allowing the sample to rest indicated gel healing. Given sufficient time, gel healing was determined to be dependent on testing temperature and polymer concentration. The time for fully healed networks was achieved on the order of minutes for the lowest concentration of 5 vol. % at temperatures of 28 and 25°C to several hours for the highest concentration of 6 vol. % at lower temperatures of 23 and 20°C.
Lastly, spherical superabsorbent polymer (SAP) gels with silica nanoparticles (SiO2) were synthesized from inverse suspension polymerization to form chemically crosslinked composite hydrogels of polyacrylamide and poly(acrylic acid). The hydrogels were studied for understanding the interaction of SiO2 nanoparticles within polyelectrolyte networks for use as a chemical admixture for internal curing of high performance concrete. The composite SAP hydrogels were produced with bare or silane-functionalized SiO2 particles to investigate the effects on swelling performance, shape, and cement paste microstructure.


Date: Tuesday, April 17, 2018

Time: 9:30 A.M.
Place: ARMS 1028

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