Dynamic physical properties of hybrid metallo-supramolecular polymer networks

CHED 725

John W. Overcash, john.overcash@duke.edu, Jennifer L. Hawk, jennifer.hawk@duke.edu, David M. Loveless, dml8@duke.edu, Sung Lan Jeon, ippsljeon@hotmail.com, and Stephen L. Craig, stephen.craig@duke.edu. Department of Chemistry, Duke University, French Family Science Center, 124 Science Dr, Durham, NC 27708
A covalent polymer scaffold of poly(2-hydroxyethyl methacrylate-co-4-vinylpyridine) was synthesized. The addition of coordinating bimetallic cross-linker, which form transient metal-ligand bonds with the pyridine residues, creates a hybrid cross-linked system where it has been shown that both the permanent and transient bonds bear stress. Four different metal cross-linkers were used to study the effect of differing ligand dissociation rates on the system. The rheological properties of the gels with and without the metal cross-linker were studied. There was an increase in compression modulus upon addition of metal cross-linker. Solvent dependence was also investigated, showing that water yielded higher moduli than DMSO. Diffusion tests were also conducted on the gels using different sized gold nanoparticles to further characterize the kinetics of the metal cross-linkers within the gels. Finally, the addition of a filler, hydroxyapatite, to the gels also produced an increase in modulus.