Abstract
Reversible
addition-fragmentation chain transfer (RAFT) polymerization of acrylamide in
methanol using dithioester RAFT chain-transfer agents was unsuccessful
due to degradation of the end group. However, this degradation was completely
suppressed by the addition of rare-earth metal triflates (RMTs). As RMTs are
effective for the stereoselective polymerization of acrylamides, RAFT
polymerization in the presence of RMTs afforded the corresponding
poly(acrylamide)s with controlled molecular weight and tacticity. The conditions allowed the synthesis of high-molecular-weight
polyacrylamides with molecular weights up to 168,000, low
dispersity (<1.5) and high tacticity (90% meso diad selectivity). The
degradation mechanism initiated by nucleophilic attack of acrylamide on the
dithioester group was experimentally clarified for the first time. As RMT is a
Lewis acid, its coordination to the amide group of acrylamide reduces its
nucleophilicity.
Supplementary materials
Title
PC RAFT SI 06
Description
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