Large area Al2O3–Au raspberry-like nanoclusters from iterative block-copolymer self-assembly. Issue 67 (11th November 2020)

• Record Type: Journal Article
• Authors: Alvarez-Fernandez, Alberto; Nallet, Frédéric; Fontaine, Philippe; Cummins, Cian; Hadziioannou, Georges; Barois, Philippe; Fleury, Guillaume; Ponsinet, Virginie
• Is Part Of: RSC advances. Volume 10:Issue 67(2020)
• Page Start: 41088
• Page End: 41097
• Publication Date: 2020-11-11
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0ra08730k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Large area Al2 O3 –Au raspberry-like nanoclusters and other complex structures have been created by iterative block-copolymer self-assembly, paving the way to a new generation of on-demand metallic architectures. Abstract : In the field of functional nanomaterials, core–satellite nanoclusters have recently elicited great interest due to their unique optoelectronic properties. However, core–satellite synthetic routes to date are hampered by delicate and multistep reaction conditions and no practical method has been reported for the ordering of these structures onto a surface monolayer. Herein we show a reproducible and simplified thin film process to fabricate bimetallic raspberry nanoclusters using block copolymer (BCP) lithography. The fabricated inorganic raspberry nanoclusters consisted of a ∼36 nm alumina core decorated with ∼15 nm Au satellites after infusing multilayer BCP nanopatterns. A series of cylindrical BCPs with different molecular weights allowed us to dial in specific nanodot periodicities (from 30 to 80 nm). Highly ordered BCP nanopatterns were then selectively infiltrated with alumina and Au species to develop multi-level bimetallic raspberry features. Microscopy and X-ray reflectivity analysis were used at each fabrication step to gain further mechanistic insights and understand the infiltration process. Furthermore, grazing-incidence small-angle X-ray scattering studies of infiltrated films confirmed the excellent order and vertical orientation over wafer scale areas of Al2 O3 /Au raspberry nanoclusters. We believe our work demonstrates a robust strategy towards designing hybrid nanoclusters since BCP blocks can be infiltrated with various low cost salt-based precursors. The highly controlled nanocluster strategy disclosed here could have wide ranging uses, in particular for metasurface and optical based sensor applications.