(640e) Conformal Layer-By-Layer Coatings on Spiky Hedgehog Particles

Authors: 
Montjoy, D. G., University of Michigan
Bahng, J. H., University of Michigan
Kotov, N. A., University of Michigan
In order to disperse inorganic catalytic nanoparticles in apolar media, chemical camouflage with surfactants is required which greatly hinders catalytic activity. Due to this barrier, there has been little investigation of inorganic catalysts in apolar solvents. This study seeks to create functional dispersible catalysts by utilizing surface corrugation to circumvent this requirement. Hedgehog Particles (HPs), recently developed in the Kotov lab, consist of polystyrene microparticles with nanoscale zinc oxide spikes that result in marked reduction of Van der Waals interactions and enable dispersion in both polar and nonpolar solvents. Layer-by-layer (LbL) assembly allows for the production of functional thin films on microscale colloids incorporating a diverse set of catalytic nanoparticles and polyelectrolytes. By expanding LbL films to more complex colloidal surface geometries featuring high corrugation such as HPs, one can engineer a new generation of colloids with high dispersion stability, a unique balance of Van der Waals, electrostatic, and other interactions as well as a diversity of chemical/biological functionalities. Conformal coating of nanocatalysts and other functional materials was achieved by LbL films, as demonstrated by electron and confocal microscopy. Furthermore, zeta potential measurements confirmed the deposition of alternately charged LbL layers. Dispersion stability in nonpolar solvents is maintained with these surface modifications indicating promise in forming a new class of omnidispersible materials. These hybrid HPs are being investigated as a novel catalytic system which can greatly expand on catalysis in hydrophobic solvents.