Seminar: Soft microgels for smart surface nanostructuring: Structural diversity and optical properties

Tuesday, 19 February 2019 - 12:00pm – Tuesday, 19 February 2019 - 1:00pm  |  ChemSci M11

Speaker: Prof. Dr. Matthias Karg

The encapsulation of inorganic nanoparticles by cross-linked polymers yields core-shell microgels that spontaneously self-assemble at air/liquid interfaces forming highly ordered monolayers[1]. Transfer of these monolayers from the interface to macroscopic solid supports allows the fabrication of hexagonally ordered superstructures with large single crystalline domains. Depending on the thickness of the polymer shell such structures possess inter-core distances from a few up to several hundred nm. Multiple depositions on one substrate[2] or deposition to substrates with different contact angles gives access to a broad range of complex superstructures including non-hexagonal 2D Bravais lattices. In this contribution we will demonstrate the structural diversity that is accessible by interfacemediated self-assembly of hard-soft core-shell microgels. Furthermore, we will show how assembly of particles with plasmonic cores can lead to superstructures that show collective optical responses that differ strongly from the single particle behavior. The observed diffractive/plasmonic coupling can be reversibly tuned by addressing the refractive index environment through changing the swelling state of a responsive hydrogel matrix[3]. This way fully reversible resonance tuning becomes possible by either solvent exchange or temperature.

[1] K. Volk et al., Adv. Mater. 24 (2015), 7332.

[2] T. Honold et al., Colloids and Surfaces A 510 (2016), 198.

[3] K. Volk et al., Adv. Optical Mater. 5 (2017), 1600971.