Chain transfer agents for raft polymerization in aqueous media

A dithioester represented by the structural formula:

• wherein:
• j is an integer from 1 to about 12;
• k is an integer from 0 to 5;
• each Rp is the same or different and is selected from the group consisting of —SO3−M+, —COOH, —COO−M+, —NH2, —NR′2, —NR′H, —NR′3+X−, PO4−M+, —OH, —(OCH2CH2)xOH, —CONH2, —CONHR′, —CONR′2, —NR′(CH2)xCOO−M+, —NR′(CH2)xOPO3−M+, —NR′(CH2)xSO3−M+, —N+R′2(CH2)xCOO−M+, —N+R′2(CH2)xOPO3−M+, —N+R′2(CH2)xSO3−M+ and —SCN;
• W is selected from the group consisting of —SO3−M+, —COOH, —COO−M+, —PO4−M+, —NR′2, —NR′3+X−, —NR′(CH2)xCOO−M+, —NR′(CH2)xOPO3−M+, —NR′(CH2)xSO3−M+, —N+R′2(CH2)xCOO−M+, —N+R′2(CH2)xOPO3−M+ and —N+R′2(CH2)xSO3−M+;
• M+ is ammonia, an ammonium ion, an alkali metal ion, an alkaline earth metal ion, or hydronium;
• R′ is independently hydrogen or an alkyl group;
• X− is selected from the group consisting of halide, sulfate phosphate, carboxylate and sulfonate;
• and
• x is an integer from 1 to about 20.