Systematic Control of Size and Morphology in the Synthesis of Gold Nanoparticles

• Published in: Particle & particle systems characterization 2014-05, Vol.31 (5), p.571-579
• Main Authors: Abdulkin, Pavel, Precht, Thea L., Knappett, Benjamin R., Skelton, Helen E., Jefferson, David A., Wheatley, Andrew E. H.
• Format: Article
• Language: English
• Subjects: Capping; Citrates; Gold; Morphology; nanoparticle; Nanoparticles; Phosphines; Planes; Synthesis; TEM; UV-vis
• ISSN: 0934-0866; 1521-4117
• DOI: 10.1002/ppsc.201300227

The synthesis of gold nanoparticles (Au NPs) capped by poly(1‐vinylpyrrolidin‐2‐one (PVP, average M¯w = 10 000 kDa) yields moderately dispersed (6–8.5 nm) product with limited morphological control while larger NPs (15–20 nm) are reliably prepared using trisodium citrate (Na3Cit) as a reductant/capping agent. Excellent size control in the intermediate 10 nm regime is achieved by hybridizing these methodologies, with highly monodisperse, polycrystalline Au NPs forming. For a Na3Cit:PVP:Au ratio of 3.5:3.5:1, anisotropic NPs with an aspect ratio of 1.8:1 suggest the systematic agglomeration of NP pairs. Enhanced control of NP morphology is allowed by the 1,2‐tetradecanediol reduction of AuIII in the presence of straight chain, molecular anti‐agglomerants. Last, ligand substitution is used to controllably grow preformed Au seeds. In spite of the extended growth phase used, the replacement of phosphine by 1‐pentadecylamine affords highly monodisperse, cuboidal NPs containing a single clearly visible twinning plane. The allowance of particle growth parallel to this close‐packed plane explains the remarkable particle morphology. Gold nanoparticles have been prepared by a variety of routes to investigate control over size and morphology. The tandem use of PVP and trisodium citrate has balanced fast polymer encapsulation with slow electric bilayer formation to achieve particles intermediate in size between established methodologies.