Templating of inorganic nanoparticles by PAMAM/PEG dendrimer–star polymers

Poly(amidoamine) (PAMAM) dendrimers with amine endgroups (PAMAM–NH2) are converted to starlike copolymers by grafting of monofunctional poly(ethylene glycol) (PEG) ‘arms’ onto the dendrimer endgroups. Generation 4, 7, and 10 dendrimers are converted to 60-arm, 235-arm, and 750-arm PAMAM/PEG stars, respectively. The dendrimer–stars are studied as polymer templates for stabilization of gold and cadmium sulfide nanoparticles of 1–6 nm diameter. PAMAM/PEG star templating reactions are studied by aqueous gel permeation chromatography, ultraviolet–visible absorption spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. PAMAM/PEG stars effectively control nanoparticle size in the same way as PAMAM–NH2 dendrimers. However, PAMAM/PEG stars are miscible with a wider range of solvents and with selected polymers (e.g. polymethyl methacrylate). Potential applications of dendrimer–inorganic hybrid materials (solution-phase catalysis, additives for polymer blends) could benefit from the versatile solubility of PAMAM/PEG stars.