A living polymerization is a reaction without transfer and termination reactions that can proceed up to complete monomer conversion. In addition, when initiation is quantitative and fast compared to the propagation reaction, polymers with precisely controlled chain length and narrow molar mass distribution can be obtained. In the case of an industrial styrene polymerization this would permit to avoid any specific washing or degassing steps, which are necessary in the radical process to remove residual monomer and low molar mass oligomers. Since head-to-head defects along the chains are absent, anionic polystyrene would exhibit also a better thermal stability than radical one. Therefore, production of anionic polystyrene (PS) would be of interest if the conditions required to control the polymerization could be adapted to the market and be able to compete economically with industrial radical processes. The use of organic solvents and of expensive alkyllithium initiators, as well as the relatively low reaction temperatures required, was some important limitation to overcome. The possibilities to achieve a quantitative living-like anionic polymerization of styrene in the absence of solvent and at elevated temperature, using inexpensive initiating systems, were the main targets identified to tremendously decrease the cost of the anionic process. This implied at first to control the reactivity and stability of initiating and propagating active species in such unusual operating conditions.
