Salt Mediated Self-Assembly of Poly(ethylene glycol)-Functionalized Gold Nanorods

• Published in: Scientific reports Vol. 9; no. 1; pp. 20349 - 9
• Main Authors: Kim, Hyeong Jin, Wang, Wenjie, Bu, Wei, Hossen, Md Mir, Londoño-Calderon, Alejandra, Hillier, Andrew C., Prozorov, Tanya, Mallapragada, Surya, Vaknin, David
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.12.2019; Nature Publishing Group
• Subjects: 639/301/357; 639/301/357/537; Gold; Humanities and Social Sciences; Laboratories; MATERIALS SCIENCE; multidisciplinary; Nanomaterials; Nanotechnology; Nearest-neighbor; Polyethylene glycol; Salts; Science; Science (multidisciplinary); Self-assembly; Silicon wafers; Vapors; X-ray scattering
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-56730-2

Although challenging, assembling and orienting non-spherical nanomaterials into two- and three-dimensional (2D and 3D) ordered arrays can facilitate versatile collective properties by virtue of their shape-dependent properties that cannot be realized with their spherical counterparts. Here, we report on the self-assembly of gold nanorods (AuNRs) into 2D films at the vapor/liquid interface facilitated by grafting them with poly(ethylene glycol) (PEG). Using surface sensitive synchrotron grazing incidence small angle X-ray scattering (GISAXS) and specular X-ray reflectivity (XRR), we show that PEG-AuNRs in aqueous suspensions migrate to the vapor/liquid interface in the presence of salt, forming a uniform monolayer with planar-to-surface orientation. Furthermore, the 2D assembled PEG functionalized AuNRs exhibit short range order into rectangular symmetry with side-by-side and tail-to-tail nearest-neighbor packing. The effect of PEG chain length and salt concentration on the 2D assembly are also reported.