Complex Colloidal Particles Research Articles

Patchy colloids: state of the art and perspectives

Recently, an increasing experimental effort has been devoted to the synthesis of complex colloidal particles with chemically or physically patterned surfaces and possible specific shapes that are far from spherical. These new colloidal particles with anisotropic interactions are commonly named patchy particles. In this Perspective article, we focus on patchy systems characterized by spherical neutral particles with patchy surfaces. We summarize most of the patchy particle models that have been developed so far and describe how their basic features are connected to the physical systems they are meant to investigate. Patchy models consider particles as hard or soft spheres carrying a finite and small number of attractive sites arranged in precise geometries on the particle's surface. The anisotropy of the interaction and the limited valence in bonding are the salient features determining the collective behavior of such systems. By tuning the number, the interaction parameters and the local arrangements of the patches, it is possible to investigate a wide range of physical phenomena, from different self-assembly processes of proteins, polymers and patchy colloids to the dynamical arrest of gel-like structures. We also draw attention to charged patchy systems: colloidal patchy particles as well as proteins are likely charged, hence the description of the presence of heterogeneously distributed charges on the particle surface is a promising perspective for future investigations.

Synthesis of Binary Complex Colloidal Particles by Using Polyelectrolyte Multilayer-Coated Particles as Templates

We report a feasible fabrication of binary complex particles based on polyelectrolyte multilayer-coated particles (PEMPs). Binary complex particles were synthesized by combination of large organic and small inorganic nanoparticles. The PEMPs were prepared by alternating adsorption of two kinds of polyelectrolytes with opposite charges onto colloidal particles. In this structure, polyelectrolytes act as a matrix to bind precursor for metal nanoparticles. Following reduction and hydrolysis of the PEMPs could generate bimetallic complexes onto PEMPs. We found that size and composition of the bimetallic complexes depend on the amount of gold precursor added to the suspension of the PEMPs.

A model for dense systems with deformable particles or molecules

A model for the computer simulation of dense systems of complex molecules or colloidal particles which is aimed at reflecting the static and dynamic properties is proposed. The objects representing particles or molecules are considered as incompressible and deformable. Various structures and dynamic states ranging from liquid-like to crystalline ones are demonstrated as a function of the deformability parameter, the changes of which appeared equivalent to changes of particle concentration. The model is presented for the two-dimensional case but can, however, be extended to three dimensions.