Linear 1-Dodecanethiol Chain Geometry vs. Branched tert-Mercaptans: Kinetic Divergence, Radical Termination Rates, and SBR Latex Particle Size Distribution
The structural distinction between linear 1-dodecanethiol and branched tert-mercaptans dictates distinct kinetic profiles in emulsion polymerization. As a chain transfer agent, the linear geometry of 1-dodecanethiol facilitates faster diffusion within the hydrophobic core of SBR latex particles compared to sterically hindered branched isomers. This kinetic divergence results in more uniform radical termination rates, directly influencing the particle size distribution. In continuous emulsion processes, the linear structure minimizes steric interference during the transfer step, allowing for precise control over molecular weight without the broadening of the polydispersity index often observed with branched analogs. Field data indicates that when substituting branched mercaptans with linear 1-dodecanethiol, operators
