Two-Dimensional Self-Organization of Polystyrene-Capped Gold Nanoparticles

Abstract

Thiol end-functionalized polystyrene chains have been introduced onto the surface of gold nanoparticles via a two-step grafting-to method. This simple grafting procedure is demonstrated to be efficient for gold nanoparticles of different sizes and for particles initially dispersed in either aqueous or organic media. The method has been applied successfully for a relatively large range of polystyrene chain lengths. Grafting densities, as determined by thermogravimetric analysis, are found to decrease with increasing chain length. In all cases, the grafting density indicates a dense brush conformation for the tethered chains. The resulting functionalized nanoparticles self-organize into hexagonally ordered monolayers when cast onto solid substrates from chloroform solution. Furthermore, the distance between the gold cores in the dried monolayer is controlled by the molecular weight of the grafted polystyrene. Optical absorption spectra recorded for the organized monolayers show the characteristic plasmon absorption of the gold particles. Importantly, the plasmon resonance frequency exhibits a distinct dependence on interparticle separation that can be attributed to plasmon coupling between neighboring gold cores.

In situ fabrication of silver nanoarrays in hyaluronan/PDDA layer-by-layer assembled structure

“…The properties of such assembled structures can be tailored by composition, geometry, and spatial arrangement of the nanoparticles [8,9]. Ag arrayed nanostructure has been extensively studied and become one of the best established systems particularly for investigation of size and shape effects on SPR phenomenon on biosensing, for instance, surface enhanced Raman scattering (SERS).…”

Self-Assembled Nanocube-Based Plasmene Nanosheets as Soft Surface-Enhanced Raman Scattering Substrates toward Direct Quantitative Drug Identification on Surfaces

“…This is attributed by the fact that the assembly process is governed primarily by the balance of core-to-core van der Waals (vdW) attractive forces and PS ligand-ligand repulsive forces. 23 Controlled removal of the surface PS ligands resulted in imbalance between steric hindrance and vdW forces, and strong vdW forces brought NCs closer together. Excessive plasma treatment (≥ 5 minutes) resulted in vdWs attractive forces being dominant, thus resulting in nanoparticle aggregation, loss of particle ordering and formation of cracks.…”

Polymer Brushes by the “Grafting to” Method

“…[48][49][50][51][52][53][54][55] Furthermore, thiol and silane substances can bear other functionalities and thereby can bring different chemical groups to a surface for further chemical modifications. Numerous examples exist for the utilization of thiol [18,[56][57][58][59][60][61][62][63][64] and silane [14,16,20,21,33,41, reactions for polymer brush preparation via the ''grafting to'' method. The modification of the surface with a grafted polymer layer can be done in either a single step or two or more steps.…”

“…The presence of a thiol group in the polymer molecule also allows one step ''grafting to'' modification of gold substrates. [18,[56][57][58][59][60][61]63,64] PS, [57,58,64] polyethylene oxide, [18,[56][57][58][59] poly(N-isopropylacrylamide), [60,94] poly[(2-dimethylamino)ethyl methacrylate], [61] and xyloglucan [63] have been attached by the reaction of gold substrate and thiol-terminated polymer chains. For instance, Nordgren et al modified xyloglucan enzymatically to introduce a thiol group into the molecule.…”