Synergistic Physiochemical Properties of Macromolecule-Metal Complexes

Colorado State University, Fort Collins CO

Investigators

Abstract

This research activity focuses on the development of macromolecule-metal complexes that exhibit synergistic thermophysical properties, and the spectroscopic detection of the underlying complexation. Metal cations from the d-block and the f-block in the Periodic Table act like magnets that induce functional polymers to occupy vacant sites in the first-shell coordination sphere of the metal center. Consequently, the formation of self-assembled mobility-restricting nanoclusters in solid polymeric complexes allows one to design materials that can withstand larger forces before failure occurs and higher temperatures prior to viscous flow or thermal degradation. This is an extension of supramolecular design that represents a new frontier in interdisciplinary macromolecular science and engineering. Organic-inorganic hybrid materials are expected to contribute significantly to the state-of-the-art in nanotechnology, and yield devices with unusually new and useful properties via molecular engineering. At the molecular level, high-resolution carbon-13 solid state NMR and Fourier transform infrared spectroscopies will be used to probe microenvironmental factors that influence metal-based coordination-driven micromixing. When paramagnetic transition metal salts form complexes with the polymers of interest, magnetic susceptibility measurements will be performed to investigate the spin-glass nature of these nanoclusters that are responsible for unique macroscopic physical properties. Temperature dependence of magnetic susceptibilities in the vicinity of the glass transition is unprecedented. The principal investigator has contributed significantly to the current state of knowledge of macromolecule-metal complexes, yet scientific literature databases suggest that there has not been much activity at the spectroscopic level to support the proposed models for metal-ligand interaction, particularly when the dissociation of these complexes coincides with the glass transition process. Metal-based coordination-driven interactions at the molecular level can be exploited in several practical areas of science and technology. For example, it is possible to (i) compatibilize polymers that are immiscible in the absence of the inorganic component, (ii) separate mixtures of alkenes and alkanes (i.e., olefin/paraffin blends) via precipitation of transition metal pi-complexes, (iii) modify the viscosity (i.e., viscosification) of polymer solutions by bridging chains and increasing their molecular weight, (iv) induce gelation and simulate the response of artificial muscles to neural impulses via cyclic expansion and contraction of gelatinous materials that contain trapped metal cations in the presence of AC electric fields, and (v) remove heavy metal contaminants from wastewater streams via water-soluble polymers that contain functional groups which act as magnets for these toxic compounds. The fundamental studies under investigation in this research project will have a direct influence on the design and use of macromolecule-metal complexes in these five areas of practical interest.