Unconventional Assembly of Bimetallic Au–Ni Janus Nanoparticles on Chemically Modified Silica Spheres

Abstract

This paper reports that Janus Au-Ni nanoparticles (JANNPs) can self-assemble onto silica spheres in a novel way, which is different from that of single-component isotropic nanoparticles. JANNPs modified with octadecylamine (ODA) assemble onto catechol-modified silica spheres (SiO2-OH) to form a very special core-loop complex structure and finally the core-loop assemblies link each other to form large assemblies through capillary force and the hydrophobic interaction of the alkyl chains of ODA. The nanocomposites disassemble in the presence of vanillin and oleic acid because of the breakage of the catechol-metal link. Vanillin-induced disassembly enables the JANNPs to reassemble into a core-loop structure upon ODA addition. The assembly of SiO2-OH and isotropic Ni or Fe3O4 particles generates traditional core-satellite structures. This unconventional self-assembly can be attributed to the synergistic effect of Janus specificity and capillary force, which is also confirmed by the assembly of thiol-terminated silica spheres (SH-SiO2) with anisotropic JANNPs, isotropic Au, and Ni nanoparticles. These results can guide the development of novel composite materials using Janus nanoparticles as the primary building blocks.

Anisotropic Particles Templated by Cerberus Emulsions

“…Colloidal polymer particles with anisotropic shapes are undergoing an unbelievable revolution in material science. − These particles possess distinct advantages over the isotropic spherical counterparts as a result of their anisotropy in shape or chemical composition. , Janus particles, for example, are biphasic colloids that have two sides with distinct chemistry and contrast properties. , They present a unique opportunity toward the building blocks, optical biosensors, functional surfactants, and electron paper − due to their distinct chemical compositions and morphologies, in particular their amphiphilic, magnetic, catalytic, optical, and electrical properties. − For instance, Janus particles fabricated by Janus emulsion as templates in our previous research served as unique emulsifiers to stabilize Pickering emulsions, and more interestingly, the emulsion inversion was successfully achieved by choosing Janus particles with different morphologies …”

Double-Layer Magnetic Nanoparticle-Embedded Silica Particles for Efficient Bio-Separation

“…Then, carboxylic group-ended silica NPs (SiO 2 -COOH NPs) were prepared using a general silica surface modification method with APTS [ 24 ] and succinic anhydride [ 25 ]. A sidrophore-inspired method was adapted to efficiently immobilize Fe 3 O 4 NPs on the surface of the silica NPs [ 26 , 27 ]. Dopamine was introduced on the surface of the SiO 2 -COOH NPs by forming an amide bond.…”

Band Edge Optical Excitation of Pyridine-Adsorbed CuAg Nanoparticles

“…Unraveling the physical and chemical properties of alloy nanoparticles with atomically precise composition (commonly known as nanoalloys) is of fundamental importance for a plethora of applications in optics, , magnetism, − and catalysis. − Nanoalloys show remarkable tunability in the properties as a result of a great variety of chemical ordering patterns (for example, core–shell, − multishell, − ordered phases, ball-and-cup, and Janus , ) that they can assume. The nanoalloys composed of weakly miscible metals favor a core–shell chemical ordering pattern in a wide range of sizes and compositions confirmed by both experimental and computational studies by several research groups. − , For example, small Cu–Ag clusters exhibit core–shell structures with Ag segregating at the cluster surface, as theoretically predicted and experimentally observed. ,,,,, This structural motif is favored by the lower surface energy of Ag (1210 compared to 2130 mJ m –2 for Cu) as well as by its larger atomic size (first neighbor distances are 2.89 and 2.55 Å for Ag and Cu, respectively) and modest but non-negligible difference in cohesive energy (2.96 vs 3.54 eV, respectively).…”

“…Unraveling the physical and chemical properties of alloy nanoparticles with atomically precise composition (commonly known as nanoalloys) is of fundamental importance for a plethora of applications in optics, 1,2 magnetism, 3−5 and catalysis. 6−8 Nanoalloys show remarkable tunability in the properties as a result of a great variety of chemical ordering patterns (for example, core−shell, 9−15 multishell, 16−18 ordered phases, 19 ball-and-cup, 20 and Janus 21,22 ) that they can assume. The nanoalloys composed of weakly miscible metals favor a core−shell chemical ordering pattern in a wide range of sizes and compositions confirmed by both experimental and computational studies by several research groups.…”