Dynamic Assembly of Polymer-Tethered Gold Nanoparticles into a 2D Superlattice at the Air–Liquid Interface: Influence of the Polymer Structure and Solvent Vapor

Abstract

The two-dimensional (2D) superlattice obtained by self-assembly of gold nanoparticle (NPs) at the air−liquid interface shows a wide range of potential applications in catalysis, sensing, electronic storage, and molecular recognition. However, the dynamic assembly process of the gold NPs at the air−liquid interface is still unclear. In this study, gold NPs grafted with thiolterminated polystyrene homopolymers (AuNPs@PS) were used as the assembly unit, and the 2D superlattice of AuNPs@PS was prepared by spreading and evaporating the AuNPs@PS toluene suspension at the air/diethylene glycol interface. The effects of polymer chain length, grafting density, and toluene vapor atmosphere on the microstructure of the superlattice were investigated as well. The microstructural evolution process of the AuNPs@PS superlattice at the air/diethylene glycol interface was monitored by the in situ grazing incident small-angle X-ray scattering (GISAXS) technique. The results demonstrate that the transition of longchain polymer-tethered NPs from random packing to face-centered-cubic packed superlattice followed by two-dimensional hexagonal packing can be observed under a toluene vapor atmosphere. Additionally, by varying the polymer chain length and solvent vapor atmosphere, the spreading rate and superlattice interparticle spacing can be well mediated. This work provides a useful guide to prepare an ordered 2D superlattice with polymer-tethered inorganic NPs.

Grafting of Poly(methyl methacrylate) with Different Sulfur-Containing End Groups on Gold Nanoparticles and Their Interfacial Assembly into Superlattice Films

“…The diffraction peak-position ratios (1: 3 : 4 : 7 ) demonstrate the formation of a long-range ordered hexagonal superlattice of AuNP@PMMA-TL 0.51 , which is in accordance with the structure shown in SEM (Figure S22). The interparticle distance of AuNP@PMMA-TL 0.51 is 24.2 nm, which was calculated by D = 4 π / ( 3 q 1 ) , where q 1 is depicted in the 1D SAXS curve . The result is very close to the value (∼24.0 nm) obtained from TEM.…”

“…Further increasing the grafting density to 0.51 chains/nm 2 , the repulsive force was large enough to isolate AuNP@PMMA-TL 0.51 . Uniformly distributed PMMA-TL ligands and the softness of the stretched chains in the SDPB regime determined an ordered superlattice film with hexagonal packing. , …”

“…37 The polymer ligands on the AuNPs were gradually extended, introducing adequate steric hindrance between ligands, which counteracted the van der Waals force attractions. 38 Further increasing the grafting density to 0.51 chains/nm 2 , the repulsive force was large enough to isolate AuNP@PMMA-TL 0.51 . Uniformly distributed PMMA-TL ligands and the softness of the stretched chains in the SDPB regime determined an ordered superlattice film with hexagonal packing.…”

Effect of Polymeric Ligand Grafting Region on Confined Assembly of Gold Nanorods in cylindrical nanopores

“…The confined assembly method entails the imposition of spatial constraints on one or more dimensions during the assembly process, resulting in the ordered arrangement of the assembled primitives under the constraint effect [17,22] . This method effectively reduces the influence of external environmental factors on the assembly process, facilitating the system to surmount the energy barrier and generate long‐range ordered structures [2,22–25] . By manipulating the confinement strength via altering the confined space, one can regulate the assembly‘s arrangement and fabricate a range of nanomaterials with intricate structures [9,26] …”

“…[17,22] This method effectively reduces the influence of external environmental factors on the assembly process, facilitating the system to surmount the energy barrier and generate long-range ordered structures. [2,[22][23][24][25] By manipulating the confinement strength via altering the confined space, one can regulate the assembly's arrangement and fabricate a range of nanomaterials with intricate structures. [9,26] In confined spaces, NP morphology is a critical factor affecting the assembly process.…”