Gold-polymer nanocomposites:: studies of their optical properties and their potential as SERS substrates

Polymer-nanometallic-particle composites have demonstrated technological potential owing to their unique optical and electrical properties. In this article, we report on composites prepared via physical vapor deposition of gold metal onto pliable polydimethylsiloxane (PDMS) polymer. Rapid Au diffusion and nanometallic-particle formation in a phase-separated surface layer of the PDMS creates unique tunable sub-surface-based composites. The rate of deposition and average Au thickness can be manipulated to tune the optical properties, which are studied by visible wavelength optical extinction spectrometry and surface-enhanced Raman scattering (SERS). DC conductivity measurements were made during Au deposition to study percolation conditions for the materials and depth profiling was performed by X-ray photoelectron spectrometry (XPS). This work presents the use of Au-PDMS nanocomposites in combination with a sample translation technique (STT) for the improved SERS qualitative and quantitative analysis. This translation approach considerably improves the reproducibility and the sensitivity of the technique by minimizing the thermal and photolytic effects inherent in SERS. The Au-PDMS nanocomposites exhibit an affinity for amine and nitro-based compounds that are biologically relevant and point toward the potential for being used as substrates for biologically based SERS experiments. Sample Raman spectra with the nanocomposite under STT-SERS conditions are included. Copyright (c) 2005 John Wiley & Sons, Ltd.