Site-Specific Functionalization of Anisotropic Nanoparticles: From Colloidal Atoms to Colloidal Molecules

Abstract

Multipodal nanoparticles (NPs) with controlled tethers are promising principal building blocks, useful for constructing more complex materials, much like atoms are connected into more complex molecules. Here we report colloidal sphere templating as a viable means to create tetrapodal NPs with site-specific tethers. Amorphous sol-gel materials were molded by the template into shaped NPs that mimic tetravalent atoms but on the length scale of colloids. Synthetic methods were developed to modify only the tips of the tetrapods with a range of possible functional groups to generate anisotropic NPs capable of directional bonding to other NPs. We also illustrate that sets of tethered "colloidal atoms" can assemble themselves into "colloidal molecules" with precise placement of the modifying colloids. The templating and tethering approaches to these anisotropic colloidal building blocks and the assembly methods are applicable to many compositions regardless of crystal structure, therefore lending themselves to the fabrication of complex assemblies, analogous to those found in the molecular regime.

Hierarchical self-assembly of suspended branched colloidal nanocrystals into superlattice structures

“…Directional electric and/or solvophobic interactions were further employed to drive the organization of spherical nanoparticles into lattices 26 . Finally, templating has been successfully applied to create hierarchical superstructures using principally spherical particles 27,28 limits to the quality and reproducibility of such assemblies and to their maximum attainable size.Branched nanocrystals such as tetrapod or octapod-shaped colloidal nanoparticles have recently emerged as promising materials for photovoltaics and electronics 27,28,30,31 , and questions have been raised on how to approach their spatial organization. Compared to the simple nanocrystals described above, the assembly of branched nanocrystals poses several further challenges.…”

“…Directional electric and/or solvophobic interactions were further employed to drive the organization of spherical nanoparticles into lattices 26 . Finally, templating has been successfully applied to create hierarchical superstructures using principally spherical particles 27,28 limits to the quality and reproducibility of such assemblies and to their maximum attainable size.…”

“…Branched nanocrystals such as tetrapod or octapod-shaped colloidal nanoparticles have recently emerged as promising materials for photovoltaics and electronics 27,28,30,31 , and questions have been raised on how to approach their spatial organization. Compared to the simple nanocrystals described above, the assembly of branched nanocrystals poses several further challenges.…”

Frustrated nematic order in spherical geometries

“…One way to address this is to coat spherical colloid particles with a thin layer of nematic liquid crystal 2 and functionalize 3 the unavoidable defects or bold spots that arise when nematic order is established on the surface of a sphere 4,5 . The number and arrangement of these defects can vary 2,6-16 , providing flexibility for tuning directional interactions that are more difficult to achieve by other methods [17][18][19][20][21][22][23][24][25][26] . Yet, many theoretically predicted structures have not been observed and control over defect location remains elusive.…”

Characterization and Application of Adsorption Material with Hematite and Polystyrene

“…Three dimensionally ordered macroporous (3DOM) materials, which consisting of a large number of macropores more than 100 nm in diameter and the walls less than 100 nm in thickness, have been used as carriers [9][10][11][12][13], adsorbents [14][15][16][17] and electrode materials [18][19][20][21][22][23]. As adsorbents, 3DOM materials with a large specific surface area and porosity are favorable to adsorption of the heavy metal ions.…”