Cationic polyelectrolytes showing an upper critical solution temperature (UCST) are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization in water at a temperature well above the UCST. The polymerization is well controlled by the RAFT process, with excellent pseudo-first-order kinetics. The cloud point is highly dependent on the polyelectrolyte concentration, molecular weight, and presence of added electrolyte. Alkylation of a neutral polymer is also conducted to obtain polyelectrolytes with different hydrophobic groups, which are shown to increase the cloud point.
Keywords: RAFT polymerization; UCST; polyelectrolytes; thermoresponsive polymers.
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