Date of Award

Spring 2023

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Morgan Stefik

Abstract

The control of block polymer micelle dimensions while in solution is critical for a range of emerging applications in diverse fields from drug delivery and nanoreactors to use as sacrificial templates for porous nanomaterials. When under kinetic control, micelles will maintain a constant average size and thus aggregation number (Nagg) through the suppression of chain exchange mechanisms. Such kinetic control effectively enables the decoupling of micelle dimensions from solution conditions. In other words, kinetically trapped micelles can resist reorganizations brough about by e.g., the addition of metal nanoparticles. However, such micelles are traditionally governed by a fickle ��N activation energy barrier that is itself deeply dependent on solvent composition, temperature etc., with minute changes in any of these often resulting in the loss of kinetic control.

These challenges, however, can be resolved with an immobilized (glassy) core-forming segment. Here, the mechanism of kinetic control is now a function of core immobility as opposed to solvent composition. Such mechanisms are particularly useful for challenging chemistries which can e.g., involve slow cross-linking materials chemistries, protracted solvent evaporation, a critical transition from a solvent-rich to a material-rich environment, which could otherwise lead to losses in entrapment with analogous ��N systems. To counter such shortcomings with ��N control, glassy micelles were recently introduced to extend independent nanoscale tunability to the most challenging materials processing routes. Here, their wide tolerance for solution conditions and extraordinary benchtop stability following the removal of all plasticizing solvents was found to make such micelles ideal candidates for a wide variety of applications. Furthermore, such micelles were also found to be receptive to swelling with core block homopolymer to affect an increase in micelle core dimension. This ultimately enables the faceted tunability of all material dimensions as both the walls and materials of the final material are independently tunable through the addition of material precursors and core block homopolymer, respectively.

Rights

© 2023, Eric R. Williams

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