In this work, we present some properties and use of a nanocomposite formed by gold nanoparticles (NPs) into poly(methyl methacrylate) (PMMA) and its application as substrates for surface-enhanced Raman spectroscopy (SERS). The nanocomposite was formed using low-energy (49 eV) ion implantation of gold in PMMA using a cathodic arc plasma gun. The gold NPs are formed spontaneously from the implanted ions and they remain isolated from each other by the polymer medium surrounding them, ensuring a spacing between the NPs of less than 10 nm (hot spot places). The NPs form below the surface, protected from the environment, guaranteeing the stability of the composite layer. Moreover, here, we present an interesting approach to concentrate analyte molecules closer to the metal surface using the swelling effect in PMMA. Using absorption of the analyte, the molecules stay in the gaps between NPs, which is a good solution for one of the biggest challenges in SERS, that is, to guide molecules to the hot spot places.

We have explored the influence of surface energy of the PDMS (polydimethylsiloxane) substrate on the wrinkling of diamond-like carbon thin films. The surface energy of PDMS can be tuned by exposure to oxygen plasma or by shallow-implantation of gold. The result is an increase in the wrinkling wavelength and amplitude. By means of a tri-layer wrinkling model, we discuss whether the major contribution to the wavelength variation is via the surface energy of the substrate or via the mechanical properties of the interface layer resulting from the surface treatment. We conclude that the surface energy of the substrate is an important property that must be considered in order to provide a complete description of wrinkling phenomena.