Thermally Stable Gold Nanoparticles with a Crosslinked Diblock Copolymer Shell

The use of polymer-coated Au nanoparticles prepared using oligomeric- or polymeric-ligands tethered by Au-S bonds for incorporation into block copolymer templates under thermal processing has been limited due to dissociation of the Au-S bond at T $>$ 100$^{\circ}$C where compromises their colloidal stability. We report a simple route to prepare sub-5nm gold nanoparticles with a thermally stable polymeric shell. An end-functional thiol ligand consisting of poly(styrene-b-1,2{\&}3,4-isoprene-SH) is synthesized by anionic polymerization. After a standard thiol ligand synthesis of Au nanoparticles, the inner PI block is cross-linked through reaction with 1,1,3,3-tetramethyldisiloxane. Gold nanoparticles with the cross-linked shell are stable in organic solvents at 160$^{\circ}$C as well as in block copolymer films of PS-b-P2VP annealed in vacuum at 170$^{\circ}$C for several days. These nanoparticles can be designed to strongly segregate to the PS-P2VP interface resulting in very large Au nanoparticle volume fractions $\phi _{p}$ without macrophase separation as well as transitions between lamellar and bicontinuous morphologies as $\phi _{p}$ increases.