Polystyrene–organoclay nanocomposites produced by in situ activators regenerated by electron transfer for atom transfer radical polymerization

2012 ◽  
Vol 32 (4-5) ◽  
pp. 235-243 ◽  
Author(s):  
Khezrollah Khezri ◽  
Vahid Haddadi-Asl ◽  
Hossein Roghani-Mamaqani ◽  
Mehdi Salami-Kalajahi
Keyword(s):  
Molecular Weight ◽  
Electron Transfer ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Polymer Matrix ◽  
Clay Content ◽  
Xrd Analysis ◽  
Size Exclusion ◽  
Atom Transfer ◽  
Scanning Calorimetry

Abstract A newly developed initiation system, activators regenerated by electron transfer (ARGET), was employed to synthesize polystyrene-organoclay nanocomposites via atom transfer radical polymerization (ATRP). ARGET ATRP was applied since it is carried out at significantly low concentrations of the catalyst and environmentally acceptable reducing agents. Conversion and molecular weight evaluations were performed using gravimetry and size exclusion chromatography (SEC), respectively. According to the findings, addition of clay content resulted in a decrease in conversion and molecular weight of nanocomposites. However, an increase of polydispersity index is observed by increasing nanoclay loading. The living nature of the polymerization is revealed by 1H NMR spectroscopy and extracted data from the SEC traces. X-ray diffraction (XRD) analysis shows that organoclay layers are disordered and delaminated in the polymer matrix and exfoliated morphology is obtained. Thermogravimetric analysis (TGA) shows that thermal stability of the nanocomposites is higher than the neat polystyrene. A decrease in glass transition temperature of the samples by increasing organoclay content is observed by differential scanning calorimetry (DSC). Transmission electron microscopy (TEM) reveals that clay layers are partially exfoliated in the polymer matrix containing 2 wt% of organomodified montmorillonite (PSON 2) and a dispersion of partially exfoliated clay stacks is formed.

Synthesis of well-defined clay encapsulated poly(styrene-co-butyl acrylate) nanocomposite latexes via reverse atom transfer radical polymerization in miniemulsion

2012 ◽  
Vol 32 (2) ◽  
Author(s):  
Khezrollah Khezri ◽  
Vahid Haddadi-Asl ◽  
Hossein Roghani-Mamaqani ◽  
Mehdi Salami-Kalajahi
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Butyl Acrylate ◽  
Size Exclusion ◽  
Spherical Particles ◽  
Atom Transfer ◽  
Sem Images ◽  
Nanoclay Content

Abstract Well-defined poly(styrene-co-butyl acrylate) nanocomposite latexes were synthesized via reverse atom transfer radical polymerization (RATRP) in miniemulsion. Successful RATRP was carried out by using a hydrophobic ligand of 4,4’-dinonyl-2,2’-bipyridine (dNbpy) and a cationic surfactant of cetyltrimethylammonium bromide (CTAB). Dynamic light scattering (DLS) results show that droplets and particles with sizes in the range of about 170 nm were formed. Overall, conversion and molecular weight evaluation were performed by using gravimetry and size exclusion chromatography (SEC), respectively. Increasing nanoclay loading resulted in an increase in the conversion and molecular weight of the nanocomposites. However, polydispersity index (PDI) values increased by adding nanoclay content. Thermal stability of all the nanocomposites improved in comparison with the neat copolymer, according to the thermogravimetric analysis (TGA) results. Differential scanning calorimetry (DSC) results showed that the glass transition temperature (Tg) increased by increasing nanoclay content. Scanning electron microscopy (SEM) images of the nanocomposite with 1 wt% of nanoclay showed a monodisperse distribution of spherical particles, with sizes in the range of approximately 170 nm, as confirmed by the DLS data. Similarly, transmission electron microscopy (TEM) images show that clay layers are delaminated and well dispersed in the matrix of nanocomposite with 1 wt% clay content.

Reverse Atom Transfer Radical Polymerization of Styrene in the Presence of Functionalized Silica Aerogel Nanoparticles

2016 ◽  
Vol 230 (10) ◽  
Author(s):  
Khezrollah Khezri ◽  
Hossein Mahdavi
Keyword(s):  
Molecular Weight ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Silica Aerogel ◽  
Structural Characteristics ◽  
Nitrogen Adsorption ◽  
Size Exclusion ◽  
Atom Transfer ◽  
Functionalized Nanoparticles ◽  
Morphological Studies

AbstractPristine silica aerogel nanoparticles surface was functionalized with 3-(trimethoxysilyl)propyl methacrylate (MPS). Then, the resultant functionalized nanoparticles were used in grafting through polymerization of styrene by reverse initiation technique for atom transfer radical polymerization. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the synthesized 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 wt % results in a decrease of conversion from 98 to 81%. Molecular weight (

scholarly journals A Cu(ii) metal–organic framework as a recyclable catalyst for ARGET ATRP

2016 ◽  
Vol 7 (47) ◽  
pp. 7199-7203 ◽  
Author(s):  
Hui-Chun Lee ◽  
Markus Antonietti ◽  
Bernhard V. K. J. Schmidt
Keyword(s):  
Electron Transfer ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Metal Organic Framework ◽  
Recyclable Catalyst ◽  
Atom Transfer ◽  
Arget Atrp ◽  
Metal Organic ◽  
Organic Framework

A Cu(ii) MOF can serve as an comprehensive catalyst for activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) in the synthesis of benzyl methacrylate, styrene, isoprene and 4-vinylpyridine.

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