Synthesis and Assembly of Anisotropic Particles

Due  to  the  presence  of  anisotropy  in  the  physical  properties,  chemical  compositions,  surface functionalities,  or  geometric  shapes,  anisotropic  particles  can  assemble  via  directional  interactions, forming large numbers of superstructures with novel collective properties that are not manifested in single particle  or  in  bulk  material.  As  such,  anisotropic  particles  are  excellent  candidates  for  more  than molecular  models  and  have  broad  ranges  of  industrial-level  applications.

Here, we present our synthetic strategies to make one particular kind of anisotropic particles: colloidal dimers.  By combination of phase separation, elastic contraction/expansion, and surface coating, we have made a variety of colloidal dimers with different characteristics, such as (1) homogeneous dimers with identical chemical composition but different sizes on each lobe; (2) heterogeneous dimers with different surface functionalities on each lobe; (3) heterogeneous dimers with different chemical compositions on each lobe; and (4) heterogeneous dimers with opposite signs of charges on each lobe. The precise control of (physical, chemical, geometrical) anisotropy on colloidal dimers allows us to study the self- and guided assembly of colloidal dimers systematically. We will also demonstrate intriguing results of assembling those anisotropic particles under different external fields, such as the electric field and convective flow field. Rich phase behaviors and transient states will be presented.