Characterization of laser ablated gold nanoparticles encapsulated in epoxy amine crosslinked sol–gel materials

Aqueous phase metal nanoparticles were formed by laser ablation and subsequently encapsulated in sol–gel derived alkyl-siloxane solids. The resulting nanoparticles were encapsulated into a mixture of hydrolyzed tetramethoxysilane and 3-glycidoxypropyltrimethoxysilane by addition of nanoparticle-containing solutions. Silanol condensation and epoxy-amine crosslinking was used to solidify the matrix. The production of gold nanoparticles and their fate upon encapsulation were characterized by the evolution of the surface plasmon absorbance band and by transmission electron microscopy (TEM). Encapsulation resulted in an increase in particle size and size distribution as well as a significant red shift in the surface plasmon absorbance band from 520 nm to 545 nm at low nanoparticle concentrations and 565 at high nanoparticle concentrations. This is attributed to chemical interactions with methanol and enhanced nanoparticle–nanoparticle interactions.