Chain transfer agents for raft polymerization in aqueous media

A dithioester or trithioester represented by the structural formula:

• 29
• wherein:
• Z comprises an alkoxy group, a group represented by the structural formula:
• 30
• or one or more aromatic or heteroaromatic groups optionally substituted by one or more hydrophilic functional groups wherein optionally there is an ether or alkylene linkage between the aromatic or heteroaromatic group and the dithioester moiety;
• and
• R comprises a group represented by the structural formula:
• 31
• wherein:
• Ar is an aromatic or heteroaromatic group;
• L is a bond, an C1-C20 azaalkylene group, or a C1-C20 straight-chained or branched alkylene group;
• R1 and R2 are each independently hydrogen, a C1-C10 alkyl group, or a cyano group;
• R3 and R4 are each independently hydrogen or a C1-C10 alkyl group when Y is N or C, and are each lone electron pairs when Y is O;
• R5 is a bond or a branched or straight-chained C1-C10 alkylene group;
• R6 is hydrogen or a C1-C10 alkyl group;
• W is selected from the group consisting of —H, —SO3−M+, —COOH, —COO−M+, —NH2, —NR′2, —NR′H, —NR′3+X−, PO4−M+, —OH, —(—OCH2CH2—)xR′, —(—CH2CH2O—)xR′, —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+, —SCN, naphthyl, and dansyl;
• 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 an integer from 1 to about 20;
• X− is a halide, sulfate, phosphate, carboxylate, or sulfonate;
• and
• Y is selected from the group consisting of N, O, and C.