POLYMERS WITH DYNAMIC BONDS: AN EXPERIMENTAL FORAY INTO THEIR FOUNDATIONAL STRUCTURE PROPERTY RELATIONSHIPS

In the world economy, polymers have enabled cost efficient innovation across nearly every sector. In recent years, polymers with dynamic bonds have shown great promise across a variety of applications ranging from plastic waste management to creating self-healing and super extensible materials.

This dissertation seeks to unravel some of the uncertainties in the field of polymers with dynamic bonds. Namely, we seek to investigate model systems, specifically designed to reveal the role certain aspects of the bond exchange process play in the interesting dynamic behavior of these systems.

The research within this dissertation begins with an exploration of rheological conceptions, misconceptions, methods of assessing terminal relaxation in dynamic bond literature, as well as key assumptions in vitrimer literature.

We then analyzed simple dynamic bonding systems which are not complicated with phase separation. We look to model hydrogen bonding systems which have an energy of dissociation greater than the threshold for the strong regime of the bond lifetime renormalization model so that this regime can be experimentally tested.

We extend this work with an investigation of a dynamic covalent linkage: the imine bond. From an analysis of these systems, we see the importance of prolonged drying for the restoration of these bonds and question the existence of an unmediated imine metathesis bond exchange pathway.

We then turn our attention to systems exhibiting phase separation of dynamic bonds and seek to apply the mechanism of bond rearrangement involving a single sticker pullout as inhibited by sticker-matrix immiscibility to several novel systems.

We begin with the study of a pendant functionalized system with identical sticker chemistry to telechelic systems, revealing identical viscoelastic behavior up to the single sticker pullout point.

We look to another system with phase separated dynamic bonds which demonstrates LCST behavior between stickers and polymer matrix, with higher activation energy for cluster relaxation than terminal relaxation, indicating cluster relaxation directly leads to terminal flow at lower temperatures.

This dissertation explores viscoelastic behavior in dynamic bonding polymers, including binary and hierarchical structures. Its conclusions aim to inform intelligent material design for these unique and desirable polymers