Polymer-Shell Coating of Mie-Resonant Silicon Nanospheres for Controlled Fabrication of Self-Assembled Monolayer

A polymer shell offers a unique opportunity to tailor the structural and optical properties of optically functional nanoparticles and their ensembles. Here, we develop a process to coat Mie-resonant silicon nanospheres (Si NSs) with a thermoresponsive poly( N -isopropylacrylamide) (PNIPAM) hydrogel shell. We show the formation of a PNIPAM shell of controlled thickness from the change of the hydrodynamic diameter and study the effect of thermoresponsive shrinkage and expansion of the shell on the Mie resonance of a Si NS. We then demonstrate that Si NSs with PNIPAM shells enable fabrication of cluster-free, self-assembled monolayers of Si NSs, in which distances between NSs are controlled by the PNIPAM shell thickness.