Effects of the environment in hydrogen-bonded polymers

Abstract

Hydrogen bonds (H-bonds) are critical noncovalent interactions in both natural and synthetic systems. While their behavior in solution is well-studied, their role in bulk polymers remains underexplored. This thesis investigates three model H-bonding systems: barbiturate/thiobarbiturate (Ba/TBa) dimers, ureido-pyrimidinone (UPy) dimers, and Hamilton wedge–barbiturate (HW-Ba) complexes, across diverse environments including solvents, ionic liquids, and bulk polymer matrices. TBa forms weaker, less ordered H-bonds than Ba, with minimal matrix effects from polyisobutylene (PIB). UPy H-bonds in polymeric ionic liquids (POILs) remain stable to 70°C, with added ionic liquids accelerating relaxation without loss of integrity. HW-Ba studies revealed solvent-dependent binding thermodynamics and enabled a two-step fixation/analysis approach in solvent-free PIB. These results highlight how local environment governs H-bond stability and provide design insights for functional polymer systems.