Bridging Nanoscale Chemistry to Bulk Properties for Polymer-Inorganic Composites

By leveraging the properties of both polymer and inorganic materials, polymer-inorganic hybrid materials offer improved properties for a diversity of applications. Recently, we developed polyurethane-inorganic composite materials that exhibit superior load-bearing performance and tunable physical properties. Yet, several fundamental aspects that pertain to the molecular structure of these PU-based materials are not currently known, and the vast formulation space limits predictable design. To this end, we develop fluorescence microscopy methods to probe spatially-dependent, heterogeneous structure-function relationships for polymer-inorganic hybrid materials. Fluorescent probes functionalized with isocyanate groups are used to image covalent linkages between single-monomer units and inorganic particles of varying chemistry, enabling in operando fluorescence microscopy to monitor the co-polymerization of diisocyanate and polyol monomers. The results hold promise to interrogate spatiotemporally-evolving characteristics of the resulting composites, including the number of polymer strands that tether to an inorganic particle, the impact of particle size and shape, reactivity differences between inorganic and organic –OH moieties, and steric effects from tethered polymer strands on inorganic-particle surface reactivity. Uncovering these crucial reactivity-structure relationships will accelerate the design of next-generation polymer-inorganic composites.