Synthesis and characterization of plasmonic nanoparticles for reconfigurable photonic metasurfaces
Supervisor: Dr Marina Santana Vega and Dr Alasdair Clark
Metamaterials have excited the scientific community for the last two decades because they present novel optical properties not found in nature.1 However, they rely on expensive techniques and specialized equipment for their fabrication, which limits their use in real life applications. This research project aims at generating reconfigurable metasurfaces as a new approach to lower fabrication costs, making it possible to regenerate the fabricated substrate to be used for a different application.
The novelty of our approach is the use of perfluorinated compounds to reversibly immobilise gold nanoparticles (AuNPs) onto nano-patterned substrates. Nanoparticle immobilization onto solid substrates is normally achieved through common surface chemistry strategies both on the substrate and the particle surface.2 Perfluorinated compounds offer the possibility of making this immobilization fully reversible, thanks to the so-called “fluorous effect”.
The fluorous effect describes the ability of perfluorinated compounds to exclude themselves from both aqueous and organic phases, associating preferably with other fluorous molecules. This enables surfaces passivated with perfluorinated chains to direct the immobilization of moieties covalently tagged with perfluorinated tails.3 This immobilization is not only highly specific, but, as mentioned above, it is also reversible due to the weak nature of the intermolecular forces between perfluorinated groups.
To fabricate these reconfigurable metasurfaces we will use electron-beam lithography to generate molecular nanopatterns using fluorous molecules. The nano-patterned surfaces will be exposed to AuNPs, which will be previously coated with a similar fluorous compound. This way, the fluorous effect will direct the AuNPs to the desired areas of the pattern, generating a metasurface. Finally, the immobilized AuNPs will be removed upon solvent rinsing to regenerate the nano-patterned substrate, allowing the immobilization of new AuNPs.
- Shuyuan Xiao et al 2020 J. Phys. D: Appl. Phys. 53 503002
- Francisco Pena Pereira et al 2012 TrAC 40, 2012, 90-105
- Gabriela E. Flinn et al Chem. Commun., 2017, 53, 3094-3097