Exploring New Methods for Polymer and Monomer Editing

Soft polymers have become intricately woven into many facets of human society. One key motivation for their continued development is the link between polymer structure and material properties. Structure modification can be accomplished through the developing diverse monomers, or through direct polymer editing. As such, developing new methods to access materials with bespoke architectures and properties is of great importance. There is a burgeoning interest in reaction manifolds that furnish highly reactive functional groups/intermediates, which open paths for degradation and functionalization previously inaccessible.

Furthermore, polymers composed of rigid carbocycles possess desirable properties and exhibit predictable property trends, in a linear manner, as a function of carbocycle content. However, longstanding synthetic limitations prevent investigation of cyclic monomers other than norbornene. Furthermore, terpenoids are bio-derived substrates which often possess carbocyclic cores. Terpenoids are not only ideal candidates to probe fundamental properties but could serve as supplements to petroleum-based materials. Herein, I present my contributions to the community’s understanding of leveraging reactive intermediates/functionalities toward polymer editing and monomer synthesis methods and expound upon our efforts to probe resulting structure property relationships.

My first project (Chapter II) centered on utilizing the Skattebøl rearrangement to embed allenes within polynorbornene. We found that these polyallenamers exhibited unique photophysical properties, and retained intrinsic reactivity of the allene moiety (e.g. [2+2] cycloadditions and Au-I mediated couplings). In a subsequent study (Chapter III), we devised a route to access polyallenamers from polymerizing a “masked” (i.e., gem-dibromocyclopropane) monomer. These polyallenamers exhibited similar photo-physical properties, were amenable to synthesis of block-like copolymers, and mechanical properties could be tuned as a function of irradiation time. Chapter IV focused on investigating underutilized methods (i.e., photoredox catalysis) to generate high energy species (radical cations) along polyalkenamers backbones. These intermediates led to chain scission and functionalization. Mechanistic experiments were conducted to support the formation of radical cations. The final project discussed (Chapter Vand VI) explore the utility of cyclic allenes and terpenoid derived allene monomers are congeners for cyclic olefin copolymers and investigations into structure property relationship as a function of carbocycle content.