A s,s-bis-(, -disubstituted-"-acetic acid)-trithiocarbonate and derivatives thereof can be used as an initiator, chain transfer agent, or terminator for polymerization of monomers such as free radical polymerizable monomers. Homopolymers, copolymers, and the like as well as block copolymers can be made utilizing the trithio carbonate compound such as in a living free radical polymerization as well as to form telechelic polymers.