کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5184042 | 1381037 | 2011 | 14 صفحه PDF | دانلود رایگان |
A surface-initiated catalytic ethylene polymerization technique is successfully demonstrated herein for the covalent surface-grafting of polyethylene chains within nanochannels of mesoporous silicas to give hybrid mesoporous silica/polyethylene composite materials. In this technique, a Pdâdiimine catalyst, [(ArNC(Me)-(Me)CNAr)Pd(Me)(NCMe)]+SbF6â(Ar = 2,6-(iPr)2C6H3) (1), was first covalently immobilized onto two ordered mesoporous silicas (SBA-15 and MSU-F) containing surface-bound acryloyl functionalities to render the mesoporous silica-supported chelate Pdâdiimine catalysts (Pd-SBA15 and Pd-MSUF, respectively). Surface-initiated ethylene polymerizations within mesopores were subsequently carried out with Pd-SBA15 and Pd-MSUF at an ethylene pressure of 400 psi and 5 °C. A mechanistic study on the polymerization behavior and the confining effects of silica meso-structures on polymer growth has been undertaken. The covalent surface-grafting of polyethylene within silica nanochannels was confirmed by the results from Fourier-transformed infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), nitrogen adsorption-desorption, electron microscopy, and proton nuclear magnetic resonance (1H NMR). The content of grafted polyethylene in the composites can be adjusted in a wide range by varying polymerization time. This represents the first report on the covalent surface functionalization of mesoporous silicas with polyethylene via surface-initiated ethylene polymerization.
Surface-initiated ethylene polymerization within nanochannels of mesoporous silicas is employed for the synthesis of silica-polyethylene composites with polyethylene chains covalently tethered on silica nanofillers.
Journal: Polymer - Volume 52, Issue 26, 13 December 2011, Pages 5961-5974