tailieunhanh - Báo cáo hóa học: " Grafting of Poly(methyl methacrylate) Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP)"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Grafting of Poly(methyl methacrylate) Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP) | Nanoscale Res Lett 2008 3 109-117 DOI s11671-008-9121-9 NANO EXPRESS Grafting of Poly methyl methacrylate Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization ATATRP Kothandapani Babu Raghavachari Dhamodharan Received 20 November 2007 Accepted 14 February 2008 Published online 4 March 2008 to the authors 2008 Abstract Poly methyl methacrylate in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization ATATRP using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr PMDETA complex without a sacrificial initiator and the grafting density is found to be as high as molecules nm2. The organic-inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography after degrafting the polymer from the magnetite core. Thermo-gravimetric analysis X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction. Keywords Magnetite nanoparticles Organic-inorganic hybrid material Phosphonic acid initiator ATRP Stable dispersion Introduction Magnetite Fe3O4 exhibits cubic inverse spinal structure and is ferromagnetic below 860 K. The large oxygen ions K. Babu R. Dhamodharan El Department of Chemistry Indian Institute of Technology Madras Chennai 600 036 India e-mail damo@ are close packed in a cubic arrangement while the smaller Fe .