Anionic polymerisation can anionic initiator generates a carbanionic intermediate and such polymerisation is termed anionic addition polymerisation. In this case, the active centre of propagating species has negative charge. So, it takes place easily with the monomer having electron withdrawing groups such as phenyl, nitrile etc. that are capable of stabilising the propagating species. Hence, CH2=CH−CN is the most reactive towards anionic polymerisation.