Investigation of Bilayer Number and Dipping Time in Polymer/Gold Nanoparticle Layer by Layer Thin Films

In plasmonics the distances between metal nanoparticles and interactions with dielectrics at the nanoscale influence electron surface oscillations which contribute to optical phenomena. Controlling the distances between these metal nanoparticles can be useful in sensor applications. In this work, the goal was to fabricate gold and multiple polymer thin films which showed plasmonic effects from single gold nanoparticles and interacting gold nanoparticles. Layer by layer samples were produced using the polymers PAH and PTEBS with 20 nm gold nanoparticles. Our goal was to find two optical absorption peaks associated with these two effects and to control their contribution via thin film design. Gold dipping time and number of bilayers were investigated. Increasing bilayer number increases the absorbance associated with single metal nanoparticles but does not lead to the second peak associated with multiple nanoparticles. Increasing gold nanoparticle dipping times also shows an increase in absorbance associated with single nanoparticles but the second peak, sometimes found in the literature, was not seen with gold dipping times up to 2 minutes and 30 seconds. Longer gold and PAH dipping times and different polymers should be investigated.