Synthesis and characterization of complex macromolecular architectures based on poly(α-olefins) utilizing a Cs-symmetry hafnium metallocene catalyst in combination with atom transfer radical polymerization (ATRP)

Abstract

Herein we describe the synthesis of block and graft copolymers made from several higher α-olefins, and in some cases styrene and methyl methacrylate, through the use of metallocene catalysts as well as the combination of metallocene and atom transfer radical polymerization (ATRP). The Cs-symmetry hafnium metallocene catalyst [(p-Et3Si)Ph] 2C(2,7-di-tert-BuFlu)(Cp)Hf(CH3)2 with tetrakis(pentafluorophenyl) borate dimethylanilinium salt, ([B(C 6F5)4]-[Me2NHPh] +), as cocatalyst, in the presence of trioctylaluminum has been used for the synthesis of the following diblock copolymers and triblock terpolymers by sequential polymerization: poly[(hexene-1)-b-(tetradecene-1)], poly[(octene-1)-b-(tetradecene-1)], poly[(hexene-1)-b-(methyl methacrylate)], poly[(octene-1)-b-(methyl methacrylate)], poly[(hexene-1)-b-(octene-1)-b- (tetradecene-1)], poly[(hexene-1)-b-(octene-1)-b-(decene-1)], and poly[(hexene-1)-b-(octene-1)-b-(methyl methacrylate)]. By combining the above metallocene catalyzed polymerization and ATRP, graft and block-graft copolymers having either poly(tetradecene-1) or poly(octene-1) backbones and poly(methyl methacrylate) or polystyrene branches were synthesized. All samples were thoroughly characterized by size exclusion chromatography, SEC, 1H and 13C NMR spectroscopy, and low angle laser light scattering, LALLS, as well as differential scanning calorimetry, DSC. © 2011 American Chemical Society.