Well-Defined Non-Linear Polyethylene-Based Macromolecular Architectures

Polyethylene (PE)-based 3- and 4-miktoarm star [PE(PCL)2, PE(PCL)3] and H-type [(PCL)2PE(PCL)2] block copolymers [polycaprolactone (PCL)] were synthesized by a combination of polyhomologation, chlorosilane chemistry, and ring opening polymerization (ROP). The following steps were used for the synthesis of the miktoarm stars: (a) reaction of a hydroxy-terminated polyethylene (PE-OH), prepared by polyhomologation of dimethylsulfoxonium methylide with a monofunctional boron initiator followed by oxidation/hydrolysis, with chloromethyl(methyl)dimethoxysilane or chloromethyltrimethoxysilane; (b) hydrolysis of the produced ω-di(tri)methoxysilyl-polyethylenes to afford ω-dihydroxy-polyethylene (difunctional initiator) and ω-trihydroxy-polyethylene (trifunctional initiator); and (c) ROP of ɛ-caprolactone with the difunctional (3-miktoarm star) or trifunctional macroinitiator (4-miktoarm star), in the presence of 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene) (t-BuP2). The H-type block copolymers were synthesized using the same strategy, but with a difunctional polyhomologation initiator. All intermediates and final products were characterized by HT-GPC, 1H NMR and FTIR analyses. Thermal properties of the PE precursors and all final products were investigated by DSC and TGA. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018