posted on 2019-01-22, 20:03authored byZhenhua Wang, Francesca Lorandi, Marco Fantin, Zongyu Wang, Jiajun Yan, Zhanhua Wang, Hesheng Xia, Krzysztof Matyjaszewski
Atom
transfer radical polymerization (ATRP) has been previously
mediated by ultrasound using a low concentration of copper complex
in water (sono-ATRP) or by addition of piezoelectric materials in
organic solvents (mechano-ATRP). However, these procedures proceeded
slowly and yielded polymers contaminated by new chains initiated by
hydroxyl radicals or by residual piezoelectrics. Unexpectedly, in
the presence of sodium carbonate, rapid sono-ATRP of methyl acrylate
in DMSO was achieved (80% conversion in <2 h) with excellent control
of molecular weights and low dispersities (Mw/Mn < 1.2). The in
situ formed CuII/L-CO3 complex in the
the presence of ultrasound generated CuI/L species as activators
for ATRP and carbonate radical anions. The latter were scavenged by
DMSO that was oxidized to dimethyl sulfone. This simple and robust
process employs low-intensity ultrasound, air-stable CuII/L catalysts, and carbonate or bicarbonate salts (washing soda or
baking soda) to prepare well-defined polyacrylates.