Synthesis and Characterization of Silver Nanoparticle Nanocomposite Thin Films with Thermally Induced Surface Morphology Changes

This work describes the preparation of thin film nanocomposites of silver nanoparticles (AgNPs) embedded in a copolymer matrix of poly(ethylene glycol) diacrylate (PEGDA) and triethylene glycol dimethacrylate (TEGDMA). The films were produced by UV-induced chemical reduction of Ag+ ions using (1,5-cyclooctadiene)(hexafluoro-acetylacetonate)silver(I) as Ag precursor, together with the photopolymerization of PEGDA and TEGDMA using 2-hydroxy-2-methylpropiophenone as photoinitiator. The average size of AgNPs increased from ca. 6nm to ca. 15nm with 1h heating at 180°C because of the nanoparticle coalescence, which causes an important change on the surface morphology. Small details were observed on the nanocomposite surface and became more evident on the heated film, as demonstrated by SEM. The morphology change is the result of migration of AgNPs towards the surface and was very clear owing to thin thickness of the nanocomposite (ca. 30μm). This nanoparticle relocation was also observed by TEM. This work offers a material that can provide important applications in which surface properties are relevant such as sensors and actuators.