Issue 35, 2018

Highly syndioselective coordination (co)polymerization of isopropenylstyrene

Abstract

Coordination (co)polymerization of para-isopropenylstyrene (pIPSt) and meta-isopropenylstyrene (mIPSt), initiated by scandium (Sc) based catalysts, afforded new type of products, bearing pendant isopropenyl groups with perfect syndiotacity (rrrr > 99%). Sc catalysts demonstrated overwhelming chemoselectivity towards the vinyl group over the isopropenyl moiety of isopropenylstyrene. Compared to the constrained-geometry Sc catalysts, having electron-donating pyridyl methylene fluorenyl ligands Flu′CH2Py (1, Flu′ = C13H8; 2, Flu′ = 2,7-tBu2C13H6, Py = C5H5N), the half-sandwich Sc catalysts containing electron-withdrawing substituents [3, C13H8SiMe3Sc(CH2SiMe3)2(THF); 4, C5Me4PhSc(CH2C6H4NMe2-o)2] showed much higher catalytic activity under identical conditions. The activity of 4 could be over 2164 kg molSc−1 h−1 at room temperature at a lower monomer concentration (1 mol L−1). Moreover, copolymerization of pIPSt and styrene (St) proceeded fluently in a pathway close to ideal copolymerization, with closely matched monomer reactivity ratios: rpIPSt = 1.05, rSt = 0.83. Therefore, a series of statically random copolymers with pendant unsaturated olefinic groups, ranging from 5% to 90%, were accessed. These pendant isopropenyl groups could be readily converted into epoxide and bromide moieties at mild reaction conditions.

Graphical abstract: Highly syndioselective coordination (co)polymerization of isopropenylstyrene

Supplementary files

Article information

Article type
Paper
Submitted
24 Apr 2018
Accepted
25 Jul 2018
First published
30 Jul 2018

Polym. Chem., 2018,9, 4476-4482

Highly syndioselective coordination (co)polymerization of isopropenylstyrene

Z. Zhang, Y. Dou, S. Li and D. Cui, Polym. Chem., 2018, 9, 4476 DOI: 10.1039/C8PY00625C

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