2D Au@PNiPAM microgel arrays suitable for photonic devices with thermally controlled interparticle gap

TL;DR

This study presents a method to assemble gold nanoparticle arrays with thermally tunable interparticle gaps using pNIPAM microgels, enabling potential applications in photonic devices.

Contribution

It introduces a simple, cost-effective approach to create thermoresponsive gold nanoparticle arrays with controllable spacing based on PNiPAM shell length.

Findings

Interparticle distance is controlled by PNiPAM shell length.

Arrays can be thermally tuned by temperature changes.

Plasma treatment degrades PNiPAM shells without affecting gold cores.

Abstract

Core-shell Au@pNIPAM nanocomposites are assembled through a simple and inexpensive approach where drops of bulk nanoparticle solution are left to dry on ITO surfaces at fixed and finely tuned temperatures. Interparticle distances are determined by the length of the thermoresponsive PNiPAM shell which acts as mechanical spacer. Structural characterization is performed through microscope imaging techniques and we quantify the pair and orientational correlation functions characteristic to each array at each deposition temperature. The elasticity of the polymer shell at each temperature is considered as microgels are softer at temperatures below PNiPAM's LCST. In a second step, previously prepared Au@PNiPAM arrays are exposed to atmospheric plasma. Plasma reacts and degrades the PNiPAM shell, being non-invasive to Au cores which remain at their original array positions.