In situ formation of gold and silver nanoparticles on uniform PDMS films and colorimetric analysis of their plasmonic color

The incorporation of metal nanoparticles (MeNPs), such as gold and silver (AuNPs and AgNPs), in polymer matrices for a diversity of applications, has gained much interest in recent years. However, a viable strategy for producing uniform samples remains challenging. In this work, we have demonstrated a facile procedure for loading AuNPs and AgNPs on previously prepared uniform polydimethylsiloxane (PDMS) films supported on glass slides, named AuNPs@PDMS and AgNPs@PDMS. The reaction of HAuCl4 or AgNO3, in an ethanol solution, with immersed PDMS films took place without the need to add other chemicals, resulting in uniform coverage of nanoparticles dependent on reaction time and temperature. Plasmonic colors of AuNPs@PDMS and AgNPs@ PDMS films were monitored collecting colorimetric data, expressed as total color difference Delta E, using a portable and handled spectrophotometer. As observed for colorimetric data, the UV-vis analysis of the SPR (surface plasmon resonance) absorption bands, at 530 nm for AuNPs@PDMS and 400 nm for AgNPs@PDMS, were dependent on the reaction time and temperature (25, 33, and 55 degrees C). The Delta E data exhibit a linear correlation with reaction time for all three investigated temperatures, and these results can be used as work curves in the future preparation of new samples. This study contributes to our understanding of the experimental conditions to produce uniform MeNPs@PDMS films with tunable plasmonic color. AuNPs@PDMS and AgNPs@PDMS films can be promising plasmonic and colorimetric sensors due to their performance and simple fabrication.