text: Controlled radical polymerization, namely reversible addition−fragmentation chain-transfer polymerization (RAFT), is a common method for the polymerization of acrylates, methacrylates and acrylamides. Usually, a thiocarbonate is used in combination with an effective initiator for RAFT. The thiocarbonate moiety can be functionalized at the R-group for end group analysis. The end group is a result of the propagation of chain-transfer agents during the free-radical polymerization process. The end groups can subsequently be modified by the reaction of the thiocarbonylthio compounds with nucleophiles and ionic reducing agents.
  The method for removal of thiocarbonyl containing end groups includes reacting the polymers containing the end-groups with en excess of radicals which add to the reactive C=S bond of the end group forming an intermediate radical (shown below). The remaining radical on the polymer chain can be hydrogenated by what is referred to as a trapping group and terminate; this results in a polymer that is free of the end groups at the α and ω positions. 
  Another method of end group removal for the thiocarbonyl containing end-groups of RAFT polymers is the addition of heat to the polymer; this is referred to as thermolysis. One method of monitoring thermolysis of RAFT polymers is by thermogravimetric analysis resulting in a weight-loss of the end group. An advantage of this technique is that no additional chemicals are required to remove the end group; however, it is required that the polymer be thermally stable to high temperature and therefore may not be effective for some polymers. Depending on the polymers sensitivity to  ultraviolet radiation (UV) it has been reported in recent years that decomposition of end-groups can be effective, but preliminary data suggest that decomposition by UV leads to a change in the distribution of molecular weights of the polymer.