(631d) Dynamics of Photo Switchable Patchy-Charged Surfaces

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. In this research, Azobenzene invariant molecules are applied as to produce photo-induced switchable  surface properties upon emitting uv light. Molecular dynamics simulations and quantum mechanical calculations were applied to design the optimal structures leading to systems with stable/metastable interchangeable properties.