Polydimethylsiloxane is an inert, non-flammable, non-toxic silicon-organic polymer that can be used as a reducing agent in the synthesis of plasmonic colloidal gold nanoparticles (AuNPs). AuNPs synthesized in PDMS take various shapes and sizes; however, it is not yet known how to control the synthesis of these AuNPs. Therefore, finding a means to control the synthesis of AuNPs in PDMS could potentially result in control over the chemical and physical transformations and further, control over the mechanical and physical properties. The photothermal effect can be employed to induce plasmonic heating via the absorption of light by AuNPs that increases the temperature to drive a variety of these chemical and physical transformations This could result in the use of AuNP/PDMS matrices in applications such as hip replacement devices, drug delivery mechanisms, and implants.<br/><br/>The size and shape of traditional colloidal nanoparticles are controlled by adjusting the metal concentration, ligand concentration, temperature, time, and solvent. As such, the first and most logical approach to control the nanoparticles synthesized in the polymer matrix was to alter the concentration of gold to polymer. UV-vis spectroscopy has confirmed nanoparticles can be synthesized from 0.05-0.15%w/v, with multiple peaks at varying wavelengths for all of the varying concentrations. These multiple peaks of variable absorbance for certain conditions confirm that different shapes and/or sizes result from varying concentration. TEM has shown that size of the AuNPs generally increases with salt concentration with a nonlinear dependence. The exact dependence is still unknown.<br/><br/>Another route used in colloidal synthesis to control the size and shapes of particles is to change the reaction time. We expected to see a change with our system if we allowed the reaction to proceed for 2 times the normal reaction time. We observe that the particles generally form spheres, the thermodynamically-preferred state. A further step in this project is to determine when in the synthesis the AuNPs assume a spherical shape. We expect to see increasing sizes of particles as the synthesis continues. This knowledge that varying concentrations and reaction time produce different types of AuNPs when synthesized in PDMS will allow for better understanding of the reaction to aid in controlling the size and shapes of the AuNPs for further tuning of the physical and mechanical properties.

Control of gold nanoparticle (AuNP) synthesis in polydimethylsiloxane (PDMS)

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.