Synthesis of gold nanoparticles grafted with a thermoresponsive polymer by surface-induced reversible-addition-fragmentation chain-transfer polymerization

Janne Raula, Jun Shan, Markus Nuopponen, Antti Niskanen, Hua Jiang, Esko I. Kauppinen, Heikki Tenhu (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

263 Citations (Scopus)


This work focuses on the synthesis method of Au nanoparticles protected by a well-defined polymer monolayer. Nanosized, spherical gold clusters coated with poly(N-isopropylacrylamide) (PNIPA) grafts were prepared by controlled radical polymerization. The polymerization of N-isopropylacrylamide was initiated from the surface of a gold nanoparticle modified with 4-cyanopentanoic acid dithiobenzoate for a reversible-addition-fragmentation chain-transfer polymerization. The number mean diameter of the Au core was 3.2 nm as observed by high-resolution transmission electron microscopy. The molar mass of the PNIPA ligand was 21000 g/mol by gel permeation chromatography. The changes in the surface plasmon of gold were investigated in different media, and as functions of particle concentration, as well as of temperature in aqueous solutions. The particles were soluble at least slightly in water, forming aggregates. The area and the maximum wavelength of the plasmon band in water decreased with dilution and increasing temperature. During the collapse of PNIPA ligands the surroundings of the gold surface change from hydrophilic to hydrophobic.
Original languageEnglish
Pages (from-to)3499-3504
Issue number8
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed



  • gold nanoparticles
  • gold
  • nanoparticles
  • stabilization
  • polymers
  • monolayers
  • surface plasmon resonance

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