Abstract
Novel polyethylene (PE)-based 3-miktoarm star copolymers A(2)B, (AB)(2)B and terpolymers (AC)(2)(BC) [A: PE; B, C: polystyrene (PS) or poly(methyl methacrylate) (PMMA)] were synthesized by combining boron chemistry, polyhomologation, and atom transfer radical polymerization (ATRP). 1,4-Pentadiene-3-yl 2-bromo-2-methylpropanoate was first synthesized followed by hydroboration with thexylborane to afford B-thexylboracyclanes, a multi-heterofunctional initiator with two initiating sites for polyhomologation and one for ATRP. After polyhomologation of dimethylsulfoxonium methylide the a,co-dihydroxyl polyethylene (PE-OH)(2)-Br produced served as macroinitiator for the ATRP of styrene to afford (PE-OH)(2)-(PSBr). Both (PE-OH)(2)-Br and (PE-OH)(2)-(PS-Br) were transformed to two new trifunctional macroinitiators (PE-Br)(2)-Br and (PE-Br)(2)-(PS-Br) through esterification reactions and used for the synthesis of (AB)(2)B and (AC)(2)(BC) 3-miktoarm star co/terpolymers. All intermediates and final products were characterized by H-1 NMR, high temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The synthetic method is a general one and can be used for the synthesis of complex PE-based architectures by combination with other living/living-controlled polymerization techniques.