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KHEZROLLAH KHEZRI,VAHID HADDADI-ASL,HOSSEIN ROGHANI-MAMAQANI 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2
Mesoporous silica nanoparticles (MCM-41) surface was functionalized with 3-(trimethoxysilyl)propyl methacrylate (MPS). Then, the resultant double bond containing nanoparticles were usedin grafting through simultaneous reverse and normal initiation technique for atom transferradical polymerization (SR&NI ATRP) of styrene to synthesize well-de¯ned polystyrene nano-composites with twofold chains. Nitrogen adsorption/desorption isotherm and X-ray di®ractionanalysis were used to evaluate characteristics of spherical MCM-41 nanoparticles. Morphologicalstudies were also performed by scanning and transmission electron microscopy. Conversion andmolecular weight determinations were carried out using gas and size exclusion chromatographyrespectively. Addition of MCM-41 nanoparticles by 3 wt.% results in a decrease of conversionfrom 93% to 82%. Molecular weight of the free and attached polystyrene chains decreases byadding 3 wt.% MCM-41 nanoparticles; however, PDI values increases from 1.27 to 1.78 for freechains and 1.87 to 2.48 for attached chains. A peak around 4.1 ppm which originates fromhydrogen atom of terminal units of polystyrene chains in proton nuclear magnetic resonancespectra in combination with low PDI values can appropriately demonstrate the living nature ofthe polymerization. Increasing thermal stability of the nanocomposites is demonstrated byThermogravimetric analysis. Di®erential scanning calorimetry also shows a decrease in glasstransition temperature by increasing MCM-41 nanoparticles.