A guide to photocuring catalyst selection

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dc.contributor.advisorPage, Zachariah
dc.contributor.committeeMemberKorgel, Brian A
dc.contributor.committeeMemberSessler, Jonathan L
dc.contributor.committeeMemberRoberts, Sean T
dc.creatorStafford, Alex Michael
dc.date.accessioned2024-07-12T20:08:02Z
dc.date.available2024-07-12T20:08:02Z
dc.date.created2023-12
dc.date.issued2023-12
dc.date.submittedDecember 2023
dc.date.updated2024-07-12T20:08:03Z
dc.description.abstractThe utilization of light as an energy source to convert liquid resins (termed photopolymers) into solid plastics is a burgeoning field in polymer science. Photopolymerizations have found broad applications in imaging and curing technologies (e.g. photoresists, photolithography, and photocurable coatings) and the driving of rapid polymerizations with visible to near-infrared light will enable nascent technologies in the emerging fields of bio- and composite-3D printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. The improvement of efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of BODIPYs, azaBODIPYs, thiopheneBODIPYs and thionaphthalimides were synthesized and systematically characterized to elucidate key structure–property relationships that correlate to efficient photopolymerization driven by visible to near-IR light. For all these scaffolds, access to longer lived photoexcited states was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (<1 mW/cm²) and catalyst loadings (<50 μM), exemplified by reaction completion within 60 s of irradiation using green, red, far-red, and near-IR light-emitting diodes. The photoredox catalysts were additionally employed to produce complex 3D structures using high-resolution visible light and near-IR 3D printing, demonstrating the broad utility of these catalysts in additive manufacturing.
dc.description.departmentChemistry
dc.format.mimetypeapplication/pdf
dc.identifier.uri
dc.identifier.urihttps://hdl.handle.net/2152/126025
dc.identifier.urihttps://doi.org/10.26153/tsw/52570
dc.language.isoen
dc.subjectPhotoredox catalysis
dc.subject3D printing
dc.subjectBODIPYs
dc.subjectPhotopolymerizations
dc.titleA guide to photocuring catalyst selection
dc.typeThesis
dc.type.materialtext
thesis.degree.departmentChemistry
thesis.degree.grantorThe University of Texas at Austin
thesis.degree.nameDoctor of Philosophy

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