Fabrication of gold nanoparticle thin film on polyimide

Abstract

Gold nanoparticles (AuNPs) deposited on typical surfaces has limitation on nonflexibility. Polyimide, which has valuable properties, such as thermal stability, resistance to organic solvents and moisture, is chosen to be substrate in this work so that the fabricated gold nanoparticles thin film on polyimide can extend the potential uses to applications such as nanoelectronic devices and sensor. In this work, fabrication of self-assembled AuNPs thin film on modified surface of glass and polyimide was investigated. Gold nanoparticles were synthesized by citrate reduction method. Deposition of gold colloid on to the substrates was done by assistance of surface modifying agent, i.e. (3-mercaptopropyl) trimethoxysilane (MPTMS), 3-aminopropyltri-methoxysilane (APTMS) and polyethylenimine (PEI). Characterizations of the deposited film were conducted using atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). It is confirmed that monolayer of AuNPs thin film can be fabricated on APTMS-and PEI-modified surface, while self-polymerization of MPTMS prevents effective deposition of AuNPs on the surface. Effects of concentration of surface modifying agent, surface modification time and AuNPs deposition time were also investigated. Density of AuNPs deposited decreases when the concentration of the modifying agent is increasing because of self-polymerization of the modifying agent, which reduced the number of functional groups requiring for the deposition of AuNPs. The amount of deposited tends to increase with an increase in the surface modification time. On the other hand, AuNPs. deposition time has small effect on the deposition of AuNPs when deposition time is longer than 4 hours. Particle size of AuNPs in the deposited film is larger when the film is annealed at higher temperature