Supplementary Information Preparation of iron nanoparticles (Fe np ) 14.3 g (53 mmol) FeCl 3 •6H 2 O was dissolved in 90 ml water then the solution of 10 g (26.4 mmol) NaBH 4 in 170 ml of water was added dropwise at 5 °C under argon atmosphere. The suspension must be vigorously stirred during the procedure. After the complete addition of the reducing agent, 3 more hours was allowed for completing the reaction. Then the suspension was stirred under oxygen atmosphere for 15 minutes, filtered,

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... atedly washed with water and ethanol. The dried nanoparticles were stored under argon atmosphere before further use. Fig. S1 Thermogravimetric analysis of a) bare Fe np , b) Fe np -1. The weight difference (3.6 %) could be translated into grafting density an average of 2.91 nm 2 per initiator. Supplementary Material (ESI) for Chemical Communications This journal is