Binuclear Scandium Initiators for the Syndiospecific Triblock Copolymerization of Styrene with ε‑Caprolactone
dataset
posted on 2020-04-29, 19:16 authored by Yang Wang, Chulu Zhou, Jianhua ChengThe binuclear half-sandwich
scandium aminobenzyl/chloride complex [(Cp′)Sc(THF)Cl]<sub>2</sub>[<i>p</i>-(CH<sub>2</sub>C<sub>6</sub>H<sub>3</sub>(<i>o</i>-NMe<sub>2</sub>)−)<sub>2</sub>] (Cp′
= C<sub>5</sub>Me<sub>4</sub>SiMe<sub>3</sub>) (<b>2</b>) was
synthesized by linking two scandium centers through a bis(aminobenzyl)
fragment. When activated with a halide abstractor, [(Et<sub>3</sub>Si)<sub>2</sub>(μ-H)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], complex <b>2</b> is capable of copolymerizing styrene and
ε-caprolactone to furnish <b>ABA</b>-type triblock copolymers
(PCL-<i>b</i>-<i>s</i>PS-<i>b</i>-PCL)
consisting of perfectly syndiospecific polystyrene (<i>s</i>PS) (<b>B</b>) in the midblock and tunable PCL (<b>A</b>) content in the end blocks. The stress–strain measurements
of a solution casting film of copolymers demonstrated that the triblock
copolymers exhibited superior mechanical performances compared to
those diblock <b>BA</b> copolymers (<i>s</i>PS-<i>b</i>-PCL) prepared from mononuclear scandium aminobenzyl/chloride
complex [(Cp′)Sc(<i>o</i>-CH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>–NMe<sub>2</sub>)(THF)Cl](<b>1</b>).
