Designing Autoregulatory Nanoparticle Array and Polymer Composite Materials

The composite material: a gold nanoparticle array embedded in a hydrogel polymer with a fluorinated surface layer; combines length scales from atomistic to microscale. When a laser excites the array local heating occurs, causing the polymer to shrink and the surface to wrinkle. The wrinkles deflect lasing and allow the system to relax. Using FTDT, the array geometry has been designed to maximize temperate change. The alteration of the mechanical properties of the hydrogel polymer due to the temperature change is essential to reproduce the wrinkling. When heated, the concentration of water in the polymer layer changes, altering the thermal and mechanical properties explored via molecular dynamics. Thermal transport is modeled using Reverse Non-Equilibrium Molecular Dynamics.¹ A pure water/polymer system is compared to a system with different salts.This atomistic information feeds into finite element mechanics calculations, where previous studies have displayed wrinkling in similar systems.² All these pieces help to create an autoregulatory humidity sensor.

1.S. Kuang, J.D. Gezelter. Molecular Physics 2012 110(9-10), 691-701
2.C.T. Chapman, J.T. Paci, W-K. Lee, C.J. Engel, T.W. Odom, G.C. Schatz. ACS Applied Materials & Interfaces 2016 8 (37), 24339-24344