Fabrication of Large Two-Dimensional Colloidal Crystals via Self-Assembly in an Attractive Force Gradient

Abstract

Colloidal particles in a water-lutidine (WL) binary liquid mixture experience temperature-dependent attraction close to the mixture's demixing temperature. This temperature-tunable interaction can be potentially harnessed to assemble colloids and grow colloidal crystals. In this article, for the first time a novel attractive force gradient method is presented to fabricate high-quality, single-domain colloidal crystals. The well-controlled attractive force gradient here arises from a temperature gradient in the WL mixture. The nucleation of colloidal crystals in such a WL mixture preferably occurs in the high-temperature region because of the stronger attraction there. Crystallization propagates from the high-temperature region to the low-temperature region in a well-controlled way. The growth of the colloidal crystal is characterized in detail by Voronoi construction, the pair correlation function, and the orientational order parameter. It is found that the number of crystal-like particles increases with time, and a single-domain 2D colloidal crystal can be produced. The mechanism of the defect-free crystallization process is discussed on the basis of an analogy to cluster beam deposition methods. This study demonstrates an efficient and robust way to prepare colloidal crystals with little to no defects, being suitable for applications such as colloidal lithography and the fabrication of perfect 3D colloidal crystals.

Advances in Colloidal Assembly: The Design of Structure and Hierarchy in Two and Three Dimensions

“…Heating close to the demixing temperature of the two liquid components strongly enhances particle attraction and leads to crystallization into a very large single-domain 2D lattice and the formation of high quality colloidal monolayers. 461 …”

Mechanical disorder of sticky-sphere glasses. I. Effect of attractive interactions

“…QSS glasses)? Intuitively, it is not surprising that attractive forces themselves stabilize mechanical structures, be them ordered [94,95] or disordered [96]. In the absence of attractive forces or a sufficient confining pressure, solidity itself would be lost, as happens near the unjamming point [38][39][40].…”

Mechanical disorder of sticky-sphere glasses. I. Effect of attractive interactions

“…QSS glasses)? Intuitively, it is not surprising that attractive forces themselves stabilize mechanical structures, be them ordered [64,65] or disordered [66]. In the absence of attractive forces or a sufficient confining pressure, solidity itself would be lost, as happens near the unjamming point [12][13][14].…”