Free radical polymerization process for preparing polymers with low polydispersity index and polymers obtained thereby. The process includes polymerizing at least one reactive monomer with at least one initiator and at least one ionic liquid (serving as solvent) to obtain polymers having a low polydispersity index of less than 1.5, wherein the reactive monomer is a nitrogen-containing monomer. In addition, the free radical polymerization processes have reaction time within 3 hours.