Master of Science
Gillies, Elizabeth R.
Self-immolative polymers (SIPs) are degradable polymers that undergo end-to-end depolymerization upon triggering. They have potential for the development of degradable surfactants addressing human and environmental toxicity concerns associated with non-degradable surfactants, but they have not yet been investigated as surfactants. Herein, polyglyoxylamide SIPs with different pendent groups and end-caps were synthesized, envisioning they could serve as depolymerizable analogues of poly(vinyl alcohol) and its derivatives. Polyglyoxylamides with pendent hydroxyls stabilized both PEA and PLA particle suspensions. They showed the potential to undergo triggered degradation, resulting in destabilization of the suspensions. However, untriggered suspensions exhibited poor long-term stability, so further structural tuning will be needed to optimize their properties for applications. Additionally, poly(ethylene glycol)-poly(ethyl glyoxylate) block copolymers were synthesized as potential emulsifiers of oil-in-water emulsions. Triggering depolymerization of the SIPs led to loss of emulsion stability, showing the promise of SIP block copolymers as a degradable and triggerable class of surfactants.
Summary for Lay Audience
Self-immolative polymers (SIPs) are a relatively recent class of degradable polymers that convert back to small molecules when exposed to stimuli such as heat, light, or reducing and oxidizing agents. They are of interest for a variety of applications.
Surfactants are molecules containing water-liking and oil-liking groups. They may solubilize a water-liking molecule in an organic (oil-liking) solvent or solubilize an oil-liking molecule in an aqueous (water-liking) solution. Surfactants have been widely used in a variety of areas such as agricultural, pharmaceutical, cosmetics, and food-processing industries.
It was envisioned that SIPs could serve as degradable versions of conventional non-degradable surfactants. This work investigates the properties of different SIPs as surfactants. The first class of synthesized SIP had a water-soluble group in its structure. Four different SIPs were investigated in this section, each with a specific speed of breakdown. The second class of synthesized SIP was attached to a water-soluble polymer, to make a polymer containing two different parts, a water-soluble and a water-insoluble parts. The synthesized SIPs were then used to prepare stable emulsions. Afterwards, they were exposed to the appropriate stimuli to investigate the effects of polymer breakdown on the stability of the emulsions. The breakdown of the SIPs led to changes in the stabilities of these systems.
Keshtpour, Siamak, "Self-immolative Polymers as a Degradable and Triggerable Class of Surfactants" (2020). Electronic Thesis and Dissertation Repository. 7510.