Colloidal nanoparticles typically consist of inorganic core and organic stabilizing ligands. The detail structural feature of both the inorganic particle and organic ligand can influence the macroscopic mechanical properties of the self-assembled systems. In this talk, I will focus on two different examples. One is the self-assembled nanoparticle membranes formed at air-liquid interface. Because of the inhomogeneous interface where the system is assembled, the surface ligand develops a subnanometer asymmetric distribution.  Temperature cycle of the membrane shows a hysteretic mechanical property that can be associated with the temperature induced reorganization of surface ligand. In a different example, I will show that the dynamical shearing of colloids consist of monodisperse nanoparticles can induce organization of nanoparticles into hexagonally stacked layers perpendicular to shear direction. As a result, the system adopt a low viscosity curve than steady shear.  Disruption of this ordered structure can induced a thickening behavior, but it occurs at a different critical shear stress than the critical shear stress for thickening during steady shear. The degree of particle monodispersity and surface roughness of the particles influence this rheological behavior drastically.  These behaviors underscore the importance in understanding the nanometer or subnanometer structural details in order to interpret the mechanical properties of self-assembled system.<br/>

Structure influence on the mechanical properties of self-assembled nanoparticle systems

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.