Chlorosilane-terminated polyethylenes having different molar masses are prepared to be used as connecting molecules between a silica surface and a neat polyethylene matrix. The synthesis and the grafting ability of such functionalized polyethylenes is reported. The grafting efficiency is demonstrated by means of Si-29 NMR and wetting measurements according to the hydrophobic nature of the grafted molecules in comparison with the hydrophilic character of the silica surface. The resulting thickness and refractive index of the dry grafted layers are characterized using spectroscopic ellipsometry. The grafting ratios are given from microanalysis measurements. Surface topography is observed using AFM. All of these techniques are in a good agreement and a general trend of the organization of the tethered layers at the surface is proposed.