(6ah) Programmable Dynamic Surfaces As Information Carriers

Tuning surface chemistry to achieve selective material properties has been an object of research for decades. Subtle variations in chemical environment at the surface of particles and materials often result in drastic changes in surface reactions, self- assemblies, surface toxicity, and more. Fine-tuning surface chemistry of materials (and/or nano particles’ surfaces) in response to environmental signals could be an efficient way to dynamic surfaces capable of adjusting their surface properties and also manipulating material objects resting on such surfaces. Change of the surface properties could be triggered by alteration or gradient in chemical potential, external fields such as electrical or magnetic fields, light, or other environmental stimuli. Potentially applications of such smart surfaces might include: transferring matter (at different scales), capture and release of ions, self-cleaning materials, “smart” delivery carriers, etc. As an example, nanoparticles functionalized by photoactive ligands might undergo conformational changes upon light irradiation ultimately altering surface properties. Careful selection of grafted functional groups at the correct ligand density could yield photoactive surfaces of the particles having dynamic surface charge density or hydrophobicity. Since the relaxation time of light-induced processes is fairly short, such photoactive particles could be applied to trap and release ions or other charged moieties. Yet another type of dynamic surfaces could be fabricated by applying charged ligands on flat substrates of macroscopic extent. Under the influence of externally applied electric fields, surface ligands could actively rearrange in regions of high-low filed. If the fields were then changing in time over the surface, they could create “waves” of surface properties that could alter effective surface properties and ultimately move around objects placed on such surfaces. My research on the design and, later, implementation of such surfaces can be facilitated by multiscale modeling with which one can gain further insights into the structures of the switchable molecules and the overall surface properties that these molecules give rise to. I am also interested in understanding such surface-dynamic phenomena at the level of fundamental thermodynamics of nonequilibrium actuation, characteristic response times, and energetic efficiencies.