|Title||Macroscopic and tunable nanoparticle superlattices|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Zhang, HH, Wang, WJ, Mallapragada, S, Travesset, A, Vaknin, D|
|Type of Article||Article|
|Keywords||2-phase systems, aqueous biphasic systems, brushes, chemistry, crystallization, curved surfaces, dna-capped nanoparticles, gold nanoparticles, Materials Science, physics, poly(ethylene oxide), polyethylene-glycol, polymer, salt, Technology - Other Topics|
onolayers transform from two-dimensional (2D) gas-like to liquid-like phase and eventually, beyond a threshold concentration, to a highly ordered hexagonal structure, as characterized by surface sensitive synchrotron X-ray reflectivity and grazing incidence X-ray diffraction. Furthermore, the method allows control of the inplane packing in the crystalline phase by varying the K2CO3 and PEG-AuNPs concentrations and the length of PEG. Using polymer-brush theory, we argue that the assembly and crystallization is driven by the need to reduce surface tension between PEG and the salt solution. Our approach of taking advantage of the phase separation of PEG in salt solutions is general (i.e., can be used with any nanoparticles) leads to high-quality macroscopic and tunable crystals. Finally, we discuss how the method can also be applied to the design of orderly 3D structures.
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