Guest-host interactions in self-assembling surfactant systems studied by NMR

COLL 291

Bradley F. Chmelka, bradc@engineering.ucsb.edu and Christian A. Steinbeck. Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106
Measurement and control of guest molecule distributions in the presence of self-assembling host species are important in many complex fluid solutions and mesostructured solids. Technologically important systems include functionalized inorganic-organic hybrid materials, micelle or vesicle hosts for drug delivery, and proteins that interact with small-molecule agents. In such mixtures, guest-host distributions may be influenced by competing dynamic interactions among numerous and diverse hydrophobic, hydrophilic, and/or surfactant species present. These interactions influence guest-host association, component mobilities, phase behaviors, and macroscopic mixture properties, though are highly system-dependent and challenging to establish. New molecular-level insights on these physicochemical properties and processes are provided by multidimensional and pulsed-field-gradient diffusion NMR methods that are sensitive to the locations, distributions, and/or dynamics of different component species. Recent results will be presented on guest-molecule interactions with self-assembling host species, e.g., block copolymer surfactants, micelles, vesicles, or proteins, in heterogeneous solutions or solids without long-range order.