Synthesis and physical behavior of weak polyelectrolyte brushes

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dc.contributor.advisorMarciel, Amanda Ben_US
dc.contributor.committeeMemberVerduzco, Rafaelen_US
dc.creatorRamezani Bajgiran, Shahryaren_US
dc.date.accessioned2024-05-22T15:44:11Zen_US
dc.date.available2024-05-22T15:44:11Zen_US
dc.date.created2024-05en_US
dc.date.issued2024-04-16en_US
dc.date.submittedMay 2024en_US
dc.date.updated2024-05-22T15:44:11Zen_US
dc.description.abstractWeak polyelectrolyte brushes (PEBs) consist of weakly charged polymers grafted to a surface and have emerged as promising candidates for responsive coatings due to their remarkable ability to undergo significant swelling and deswelling in response to changes in pH and ionic strength. This unique property holds immense potential for diverse applications in separation processes, drug delivery, and biosensing. The full potential of weak PEBs, however, is hampered by an incomplete understanding of their swelling behavior in response to various stimuli. Moreover, it has been shown that the swelling behavior of weak PEBs has a hysteretic memory response. This phenomenon manifests as a distinct difference in the swelling response when increasing or decreasing the pH, leading to unpredictable and unreliable performance in practical applications. To address these challenges, a comprehensive understanding of the physical factors that govern the swelling behavior of weak PEBs is essential. In this work, we investigated how pH, salt, and ionizable monomer fraction influence weak PEB swelling behavior. We synthesized a series of weakly charged polybasic brushes with varying fraction of ionizable monomers using an environmentally friendly surface-initiated polymerization technique with superior control and reproducibility over the polymerization kinetics. We used spectroscopic ellipsometry (SE), atomic force microscopy (AFM), and surface zeta potential measurements to characterize the swelling behavior and charge state of the brushes. We found that the pH-dependent swelling and hysteretic behavior of weak PEBs significantly increase as the fraction of ionizable monomers increases. Whereas salt concentration results in a complex non-monotonic swelling and hysteretic behavior. Lastly, to better understand the transport of particles within weak PEBs, we used a 3D super resolution tracking technique on a model charged tracer. We uncover significant spatial heterogeneities and find two distinctly different modes of motion within a weak PEB. Overall, our findings on the swelling behavior of weak PEBs and their interactions with particles can facilitate the design of more efficient stimuli-responsive coatings that use weak PEBs in various applications.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationBajgiran, Shahryar Ramezani. Synthesis and physical behavior of weak polyelectrolyte brushes. (2024). PhD diss., Rice University. https://hdl.handle.net/1911/116163en_US
dc.identifier.urihttps://hdl.handle.net/1911/116163en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectPolymer Scienceen_US
dc.subjectPolyelectrolytesen_US
dc.subjectPolymer brushesen_US
dc.subjectpH-responsive surface coatingsen_US
dc.titleSynthesis and physical behavior of weak polyelectrolyte brushesen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemical and Biomolecular Engineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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