Water-Mediated Assembly of Gold Nanoparticles into Aligned One-Dimensional Superstructures

Abstract

This Article shows that water in ethanol colloids of gold nanoparticles enhances the formation of linear clusters and, more important for applications in electronics, determines their assembly on surfaces. We show by dynamic light scattering that ethanol colloids contain mainly monomers and dimers and that wormlike superstructures are mostly absent, despite UV-vis evidence of aggregation. Water added to the colloid as a cosolvent was found to enhance the number of clusters as well as their average size, confirming its role in linear self-assembly, on the scale of a few particles. Water adsorbed from the atmosphere during coating was also found to be a powerful lever to tune self-assembly on surfaces. By varying the relative humidity, a sharp transition from branched to linear superstructures was observed, showing the importance of water as a cosolvent in the formation of cluster superstructures. We show that one-dimensional superstructures may form due to long-range mobility of precursor clusters on wet surfaces, allowing their rearrangement. The understanding of the phenomenon allows us to statistically align both clusters and resulting superstructures on patterned substrates, opening the way to rapid screening in molecular electronics.

1D Colloidal chains: recent progress from formation to emergent properties and applications

“…12c). 506 An alternative approach to the formation of 1D colloidal chains mediated by small molecules is using small molecules with bifunctional groups as linkers conjugating adjacent NPs via chemisorption, [517][518][519] electrostatic interaction, 520-522 complexation, 157,523 hydrogen bonding, 493,524 or direct covalent bonds. 525 Frequently used molecular linkers are amino acids, 520,521,524,526 alkane dithiols, 517,518 divalent metal ions such as zinc and magnesium ions, 157,523 and other bifunctional small molecules (Fig.…”

Continuous and discontinuous transitions between two types of capillary bridges on a beaded chain pulled out from a liquid

“…[14][15][16] They are often utilized in material science, e.g. for fabricating new materials using capillary suspensions, [17][18][19] new structures, [20][21][22] in nanolithography, [23][24][25] microplating, 26 for pattern formation, 27 and in printed electronics technologies. 28 It is thus essential to know their properties and behavior.…”