Surface-initiated catalytic ethylene polymerization within nano-channels of ordered mesoporous silicas for synthesis of hybrid silica composites containing covalently tethered polyethylene
作者：L. Xu, Z. Ye*, Q. Cui, Z. Gu, L. Mercier
關(guān)鍵字：Ordered mesoporous silica, Pd–diimine catalyst, Covalent surface-grafting
論文來源：期刊
具體來源：Polymer
發(fā)表時間：2011年
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 Pd?diimine catalyst, [(ArNC(Me)–(Me)CNAr)Pd(Me)(NCMe)]+SbF6?(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 Pd?diimine 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.