Water soluble chain transfer agents

A method of chelating ions of hardness from an aqueous medium comprising adding to an aqueous medium a water soluble polymer comprising (A) at least one water soluble Chain Transfer Agent (“CTA”)-acid or CTA-acid salt and combinations thereof, (B) monomer units derived from at least one water soluble monomer, and optionally (C) monomer units derived from at least one water insoluble vinyl monomer

• wherein the water soluable CTA-acid comprises a thiocarbonate compound having the formula I
• wherein
• each of R1 and R2 is an alkyl group of four carbons or less or H,
• so long as the sum of the number of carbon atoms present for all R1, and R2 in formula I together is less than four;
• or formula II
• wherein
• each of R1 and R2 is as defined above;
• and
• R3 is an alkyl group of four carbons or less, or H,
• so long as the sum of the number of carbon atoms present for all R1, R2 and R3 in formula II together is less than four;
• or formula III
• wherein
• each of R4 and/or R5 substituents, independently, comprise an alkyl group having from 1 to 4 carbon atoms, or H;
• j is 1 or 2, with the proviso that when j is 1, T is NR6R7);
• and when j is 2, T is a divalent radical having a nitrogen atom directly connected to each carbon atom of the two thiocarbonyl groups present;
• R6 and R7, independently, are the same or different, and are H or a linear or branched alkyl having from 1 to 4 carbon atoms;
• so long as the sum of the number of carbon atoms present for all R substituents in formula III together is less than four;
• or formula IV
• wherein
• each of R4, and R5 are as defined above
• R13 is optionally substituted, and is a linear or branched alkyl having from 1 to 4 carbon atoms;
• and
• a is 1 to 4;
• so long as the sum of the number of carbon atoms present for all R substituents in formula IV together is less than four.