Synthesis Methods and Strategies for MIPs

Molecularly imprinted polymers (MIPs) are described by the molecular imprinting technology that allows the creation of tailor-made binding sites of the same shape, size, and functional groups of the target. Therefore, the MIPs absorb the target via fabricated cavities that are complementary to the template molecule. Since MIPs are widely used, their synthesis method is considered a necessary process. This technology consists of three strategies: covalent, non-covalent, and semi-covalent approach, which non-covalent approach is the most common because of its experimental simplicity. In this approach, the target is removed from the MIP and a fast mass transfer rate is achieved because the monomer bonds with the template through the non-covalent interaction. In the covalent strategy, the interaction between monomer and template is covalent bonds reversible. Target rebinding is based on the break or creation of covalent interaction. The semi-covalent approach has the advantages of both methods. In this approach, covalent interaction between the target and functional monomer was applied during the synthesis, but non-covalent interaction was employed during the target rebinding. There are two main mechanisms for MIP synthesis including free-radical polymerization and sol–gel process. Free-radical polymerization consists of suspension, bulk, precipitation, seed, emulsion, in-situ, and microwave polymerization. On the other hand, the sol–gel method includes embedding, copolymerization, template pore-forming, and multi-stage imprinting. This chapter introduces the general overview of synthesis methods and strategies of MIPs, their basic principles, and some influential factors in MIP synthesis. Moreover, the advantages and disadvantages of each technique are discussed.