Department Chair or Program Director
Bachelor of Science
Major or Concentration
Department or Program
Nanoparticle-polymer composites (NPC's) consist of an insulating polymer containing nanoparticles. For NPC's containing metallic particles, the composite becomes conductive at a specific volume fraction, known as the percolation threshold. Previous studies found NPC's to be conductive when the particles were not in contact, suggesting that electrons may be tunneling through the matrix. Additionally, all metallic particles exposed to air have an oxide shell. Since oxides are semiconductors, this increases the electrical complexity of the nanocomposite. This research evaluated the effect of the oxide layer on particles in a NPC through treatment of percolation and quantum tunneling theories to explore the conductive behavior in RF fields. Quantum mechanics was used to evaluate the probability of an electron tunneling between two Cu or CuO particles in an insulating matrix. The transmission probability for an electron to tunnel from one Cu nanoparticle to another in a PMMA matrix with an electric potential of 60 V was found to be very high, with tunneling 95% probable until 200 nm particle separation. After the incorporation of an oxide shell, the tunneling distance at 95% probability increased to 300 nm. A percolation model was constructed in MATLAB, where the tunneling distances for Cu and CuO particles were incorporated to estimate the volume fraction of a NPC. The addition of the oxide layer increased the tunneling distance between particles and decreased the percolation threshold needed to obtain a conductive NPC.
Killian, Hannah, "Effect of Oxide Layer Thickness on Tunneling-Percolation Threshold in Nanoparticle-Polymer Composites" (2019). Student Research Submissions. 270.