Schiff base
Most of the approaches currently used to synthesize CMPs must be carried out under anhydrous and oxygen-free environments due to the presence of metal catalysts. Due to the use of metal catalysts, polymers inevitably have trace metals present. Reactions, such as the Schiff base reaction, have garnered much attention in that the reactions are metal free. In Schiff base, amine based monomers and aldehyde containing monomers undergo a reaction to create the repeat unit for CMPs. Schiff base is a preferred metal free method due to industrial scale cheap monomers containing multiple aldehyde functional groups. Another benefit of Schiff base is nitrogen is produced in creating CMPs, which could be beneficial for many applications.