Wet‐Chemical Synthesis of Amphiphilic Rodlike Silica Particles and their Molecular Mimetic Assembly in Selective Solvents

Abstract

Nano-and micrometer-sized colloidal particles (CPs) with shape anisotropy (e.g., rod-shaped particles) and chemical heterogeneity (e.g., patchy particles) have attracted significant attention owing to their fascinating optical, electronic, and magnetic properties in materials sciences. [1][2][3] Self-assembly of such colloidal building blocks as "atoms" or "molecules" (so-called "colloidal molecules") into novel architectures or ordered ensembles provides new opportunities for engineering materials and devices with otherwise unattainable properties. [4,5] In particular, assembly of rodlike CPs with two or multiple blocks can potentially produce a variety of spectacular structures, which arise from the interplay and competition of the structural asymmetry of rods, the orientation, and phase segregation of blocks. [1a, 6] Currently, the preparation of such segmented rodlike CPs mainly relies on templated electrochemical deposition, [7] galvanic replacement, [8] phase separation, [3f] chemical vapor deposition, [9] hot coordinating solvents method, [10] and cation-exchange reactions. [11] These approaches, however, are either limited to crystalline or conductive materials, or they require the use of templates. The synthesis of segmented rodlike particles from amorphous materials (e.g., SiO 2 ) still remains a challenge.From the study of the assembly of colloidal molecules one can fundamentally learn and understand the general principles of atomic and molecular interactions using CPs as model systems, [1,12] and one can practically use the strategy known from the self-assembly of atoms or molecules as an inspiration for the design of new functional materials of CPs, such as nonconventional photonic crystals. [3d, 13] Anisotropic rodlike CPs with hydrophilic and hydrophobic blocks are typical models for the investigation of assembly behaviors and molecular interactions of amphiphilic molecules (AMs). [8] The Mirkin group reported an inspiring example of template-directed assembly of two-segment gold-polypyrrole (Au-PPy) rods prepared by a templating method. [7a] The assembly of Au-PPy rods is driven by a delicate balance of [*] Dr.

Synthesis of Segmented Silica Rods by Regulation of the Growth Temperature

“…[4][5][6][7][8][9][10] Subsequent addition of precursors led to various hybrid structures, such as patchy particles and rods. [11,12] Despite tremendous progress in obtaining structures of predicted morphologies, it is still challenging to achieve control of the local diameter with correlating control of size. For example, there is no example demonstrating the synthesis of segmented (corrugated or grooved) silica rods, although they are highly desirable for applications such as antireflective coatings.…”

Synthesis of Half‐Sphere/Half‐Funnel‐Shaped Silica Structures by Reagent Localization and the Role of Water in Shape Control

“…[11] Metal particless uch as gold and silver have also been deposited on the preformeds ilica rods. [14,15] By exploiting short-range order between silica rods, thermoreversible gels have also been synthesized. [13] The rods have been also self-assembled and growno np orous composites.…”

“…[13] The rods have been also self-assembled and growno np orous composites. [14,15] By exploiting short-range order between silica rods, thermoreversible gels have also been synthesized. [16] However,afew efforts have been made to understand the underlying mechanisms related to the effects of different reagents on rod growth.…”

Facile synthesis of asymmetric Ag–organosilica hybrid nanoparticles with tunable morphologies and optical properties

“…2a). 12 After 2 min, these soft floccules grew into small organosilica bumps on the surfaces of the Ag NPs (Fig. 2b).…”