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Hydrophilic silica aerogel nanoparticles' surface was functionalized with 3-(trimethoxysilyl)propyl methacrylate (MPS). Then, the resultant functionalized nanoparticles were used in grafting through copolymerization of styrene and butyl acrylate by simultaneous reverse and normal initiation technique for atom transfer radical copolymerization (SR&NI ATRP) to synthesize tailor-made random poly (styrene-co-butyl acrylate) nanocomposites with twofold chains. Successful surface modification of hydrophilic silica aerogel nanoparticles with MPS is demonstrated by Fourier transform infrared spectroscopy and thermogravimetric analysis (TG). Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the synthesized silica aerogel nanoparticles. Evaluation of size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Addition of MPS-functionalized nanoparticles by 3 mass% results in a decrease in conversion from 71 to 46 %. Molecular weight ( M ) of the free poly (styrene-co-butyl acrylate) chains decreases by adding 3 mass% MPS-functionalized silica aerogel nanoparticles; however, polydispersity index (PDI) value increases from 1.17 to 1.48. Although PDI values of the attached poly (styrene-co-butyl acrylate) chains are increased from 1.54 to 1.76, M values reveal an increment by adding silica aerogel nanoparticles. H NMR spectroscopy results indicate that the molar ration of each monomer in the copolymer chains is approximately similar to the initial selected mole ratio of the monomers. Increasing thermal stability of the nanocomposites is demonstrated by TG. Differential scanning calorimetry also shows a decrease in glass transition temperature by increasing modified silica aerogel nanoparticles. [ABSTRACT FROM AUTHOR]

An organic modifier with vinyl moiety, 3-(trimethoxysilyl)propyl methacrylate (MPS), was employed to surface modification of hydrophilic silica aerogel nanoparticles. After that, double bond moieties on the surface were incorporated in grafting through polymerization of methyl methacrylate (MMA) via in situ simultaneous reverse and normal initiation technique for atom transfer radical polymerization (SR&NI ATRP). Grafting through polymerization of MMA results in tailor-made poly(methyl methacrylate) (PMMA) with twofold chains. Successful surface modification of hydrophilic silica aerogel nanoparticles with MPS is demonstrated by Furrier transform infrared spectroscopy and thermogravimetric analysis (TGA). Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the synthesized silica aerogel nanoparticles. Evaluation of size distribution and morphological studies were performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Addition of MPS-functionalized silica aerogel nanoparticles by 3 wt% results in decrement of conversion from 87 to 66%. By adding 3 wt% MPS-functionalized silica aerogel nanoparticles, molecular weight (M n ) of free MMA chains decreases from 13,563 to 9365; however, polydispersity index (PDI) value increases from 1.19 to 1.56. Although PDI values of attached MMA chains are increased from 1.48 to 2.08, M n values reveal an increment by adding MPS-functionalized silica aerogel nanoparticles content. Low PDI values of the products can appropriately demonstrate the living nature of polymerization. An increment of thermal stability of the nanocomposites by increasing MPS-functionalized silica aerogel nanoparticles is demonstrated by TGA results. Differential scanning calorimetry also shows a decrement in glass transition temperature by increasing MPS-functionalized silica aerogel nanoparticles loading. [ABSTRACT FROM AUTHOR]