||January 1, 2006
Controlling the chain length, the molecular weight distribution as well as the cross-linking density of a polymer are crucial in tailoring its properties to meet specific application requirements. This goal is achieved using Chain Transfer Agents (CTA) such as mercaptans, which are commonly used in the free radical synthesis of numerous polymers and latexes. Tertiary Dodecyl Mercaptan (TDM) is the standard CTA used in the production of SBLatex (paper coating industry, carpet backing), SBR (tire industry), ABS and Polystyrene. Linear mercaptans like n-dodecyl mercaptan (NDM) are preferred when acrylic and methacrylic monomers are used in the synthesis of PMMA, acrylic acid and ester derivatives and their copolymers. A new generation of CTA's from sulfur family that function via Reversible Addition Fragmentation Transfer mechanism is emerging in the last few years that allows us to achieve more complex polymer architectures. In this paper, the behavior of four different CTA's from both families will be compared in a standard emulsion recipe using various monomers, demonstrating the need to carefully choose the right CTA to obtain polymers with the desirable properties for specific applications.