Title

Polymer Networks for Phosphate Recognition and Sequestration

Presenter Information

Natalie JarrettFollow

Academic Level at Time of Presentation

Senior

Major

Chemistry (area)

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Dr. Kasey Clear

Presentation Format

Oral Presentation

Abstract/Description

Phosphate oxyanions such as phosphate, pyrophosphate, glyphosate, and nucleotides are prevalent in both biological and environmental contexts, and consequently there is a need for methods to recognize and sense these anions. In some situations, such as environmental cleanup of phosphates or treatment of medical conditions (e.g. hyperphosphatemia), materials that can bind tightly to phosphate anions are needed. Polymer networks are intriguing materials for these applications due to their ability to sequester anions from solution and the ease at which they can be removed from solution after capturing the anion. Because anions found in aqueous environments are often hydrophilic and highly solvated, films and gels being studied must be hydrophilic. Furthermore, the polymers must be attractive enough to pull the specific anion out of water and into the network. One way this has been achieved is by incorporating anion recognition groups into the polymer to create a network with high affinity for anions. In this thesis, polymer networks are formed by free radical polymerization of 2-hydroxyethyl acrylate (HEA) using 1,4-butanediol diacrylate as the crosslinker. The resulting polymer is hydrophilic and can swell in water. To improve the affinity of the network for anions, pHEA is copolymerized with alkene monomers functionalized with varying ratios of a metal coordination complex (Zn-DPA) or guanidinium. These polymers are placed into aqueous phosphate solutions and left to absorb anions. Absorptivity and selectivity for phosphate species is determined by the difference in concentration of phosphate in the solution after the introduction of the polymer versus original concentration. To measure the concentration differences quantitatively, colorimetric phosphate detection assays are used. Change in absorbance is measured using UV-Vis spectrometry and calibration curves are made per phosphate species to determine the percent of phosphate that has been incorporated into the polymer network. The results of this work provide insight into structural requirements for phosphate affinity and selectivity in polymer networks.

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Polymer Networks for Phosphate Recognition and Sequestration

Phosphate oxyanions such as phosphate, pyrophosphate, glyphosate, and nucleotides are prevalent in both biological and environmental contexts, and consequently there is a need for methods to recognize and sense these anions. In some situations, such as environmental cleanup of phosphates or treatment of medical conditions (e.g. hyperphosphatemia), materials that can bind tightly to phosphate anions are needed. Polymer networks are intriguing materials for these applications due to their ability to sequester anions from solution and the ease at which they can be removed from solution after capturing the anion. Because anions found in aqueous environments are often hydrophilic and highly solvated, films and gels being studied must be hydrophilic. Furthermore, the polymers must be attractive enough to pull the specific anion out of water and into the network. One way this has been achieved is by incorporating anion recognition groups into the polymer to create a network with high affinity for anions. In this thesis, polymer networks are formed by free radical polymerization of 2-hydroxyethyl acrylate (HEA) using 1,4-butanediol diacrylate as the crosslinker. The resulting polymer is hydrophilic and can swell in water. To improve the affinity of the network for anions, pHEA is copolymerized with alkene monomers functionalized with varying ratios of a metal coordination complex (Zn-DPA) or guanidinium. These polymers are placed into aqueous phosphate solutions and left to absorb anions. Absorptivity and selectivity for phosphate species is determined by the difference in concentration of phosphate in the solution after the introduction of the polymer versus original concentration. To measure the concentration differences quantitatively, colorimetric phosphate detection assays are used. Change in absorbance is measured using UV-Vis spectrometry and calibration curves are made per phosphate species to determine the percent of phosphate that has been incorporated into the polymer network. The results of this work provide insight into structural requirements for phosphate affinity and selectivity in polymer networks.