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

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 C_s-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.