Summary: An active model for a Ziegler-Natta propylene polymerization catalyst has been prepared ... more Summary: An active model for a Ziegler-Natta propylene polymerization catalyst has been prepared by spin-coating of a MgCl2/diether donor solution in ethanol on a flat silica wafer, followed by crystal growth by Ostwald ripening to give well-defined MgCl2 Á diether Á nEtOH ...
ABSTRACT A method to prepare films of conspicuous domains of cellulose on a closed cellulose laye... more ABSTRACT A method to prepare films of conspicuous domains of cellulose on a closed cellulose layer is introduced. These films can be used as model surfaces which are closer to the natural environment than most organic model surfaces that are usually coated directly on an inorganic substrate. The method is based on spin-coating a hydrophobic derivative of cellulose, trimethylsilylcellulose (TMSC), blended with polystyrene (PS) onto a silicon substrate. TMSC can be hydrolyzed to cellulose with acid hydrolysis, leaving domains of cellulose and PS embedded on a sublayer of cellulose. Selective dissolving of PS leaves a closed cellulose surface (sublayer) with eminent cellulose domains whose size depends on the original TMSC/PS ratio. The chemistry of the films was analyzed with X-ray photoelectron spectroscopy (XPS) and the morphology with atomic force microscopy (AFM). Scrutiny of the AFM data showed that the films are quantifiable and quantitatively reproducible.
... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmui... more ... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmuir 2004 20 (22), 9456-9462. ... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmuir 2004 20 (22), 9456-9462. ...
A surface science model for a silica supported bis(imino)pyridyl iron complexes is applied to rev... more A surface science model for a silica supported bis(imino)pyridyl iron complexes is applied to reveal the surface chemistry of these heterogeneous polymerization catalysts. The polymerization activity of these models and the molecular weight distribution of the resulting polymer are comparable to similar catalysts supported on amorphous silica. The catalyst deactivates partially during the first hour of ethylene polymerization. Based on photoelectron spectroscopy (XPS) we attribute this deactivation to iron extrusion by the aluminium alkyl activator.
Summary: An active model for a Ziegler-Natta propylene polymerization catalyst has been prepared ... more Summary: An active model for a Ziegler-Natta propylene polymerization catalyst has been prepared by spin-coating of a MgCl2/diether donor solution in ethanol on a flat silica wafer, followed by crystal growth by Ostwald ripening to give well-defined MgCl2 Á diether Á nEtOH ...
ABSTRACT A method to prepare films of conspicuous domains of cellulose on a closed cellulose laye... more ABSTRACT A method to prepare films of conspicuous domains of cellulose on a closed cellulose layer is introduced. These films can be used as model surfaces which are closer to the natural environment than most organic model surfaces that are usually coated directly on an inorganic substrate. The method is based on spin-coating a hydrophobic derivative of cellulose, trimethylsilylcellulose (TMSC), blended with polystyrene (PS) onto a silicon substrate. TMSC can be hydrolyzed to cellulose with acid hydrolysis, leaving domains of cellulose and PS embedded on a sublayer of cellulose. Selective dissolving of PS leaves a closed cellulose surface (sublayer) with eminent cellulose domains whose size depends on the original TMSC/PS ratio. The chemistry of the films was analyzed with X-ray photoelectron spectroscopy (XPS) and the morphology with atomic force microscopy (AFM). Scrutiny of the AFM data showed that the films are quantifiable and quantitatively reproducible.
... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmui... more ... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmuir 2004 20 (22), 9456-9462. ... Pathways, and Implications for Catalysis. Christopher P. Nicholas and Tobin J. Marks. Langmuir 2004 20 (22), 9456-9462. ...
A surface science model for a silica supported bis(imino)pyridyl iron complexes is applied to rev... more A surface science model for a silica supported bis(imino)pyridyl iron complexes is applied to reveal the surface chemistry of these heterogeneous polymerization catalysts. The polymerization activity of these models and the molecular weight distribution of the resulting polymer are comparable to similar catalysts supported on amorphous silica. The catalyst deactivates partially during the first hour of ethylene polymerization. Based on photoelectron spectroscopy (XPS) we attribute this deactivation to iron extrusion by the aluminium alkyl activator.
Uploads
Papers