(6ey) Directed Assembly at All Length Scales: The Pathway Towards Future Metamaterials

Assembling building block molecules and particles is the key to fabricate functional materials. The equilibrium morphology of the self-assembled state is determined by the building block packing efficiency (entropy) and interparticle interaction (enthalpy). My research focuses on the fundamental understanding of these governing factors and developing new ‘assembly principles’ for organizing building blocks at all scales; from molecular to particulate. At the molecular level, we proposed methods for directing the assembly of amphiphiles on silica nanoparticles and under confined nanopores of SBA-15 materials. We also developed approaches for triggering the release of surface bound amphiphiles on-demand by co-adsorption of displacer molecules. Recently, we discovered a new method for assembling superparamagnetic nanoparticles into magnetically-responsive ultraflexible filaments via ‘nanocapillary’ lipid bridging. We reported that the filament and their networks can be healed upon mechanical damage. Secondly on the nanoscale, we established the fundamentals of colloidal interactions between silica nanoparticles and biologically relevant entities such as globular proteins. We revealed how the adsorbed protein induces a pH-dependent reversible aggregation of the particles. A similar route of modulating colloidal interactions was used to fabricate lignin based environmentally benign antimicrobial nanoparticles. The particles exhibited time-limited activity and were shown to be a potentially safer substitute to the presently used silver nanoparticles. Finally at the microscale, we demonstrated that oppositely charged particles can be assembled into rigid permanent chains using dielectrophoresis as a structure directing tool. In addition, we developed novel strategies for assembling anisotropic shaped microparticles into self-reconfigurable and reversibly actuating active structures which can be used as soft-robotic components. The assembly principles developed can be used for engineering a wide range of functional materials providing efficient and environmentally friendly solution to the present day needs of the society.