## 2 Synthesis and Characterization of MIP
### Polymerization Parameter in MIP Synthesis
#### 2.1.3 Crosslinker  
Monomers are copolymerized around a template via covalent bonding, and are arranged in space to form stable complementarity. The majority of the imprinting methods require a high number of crosslinkers in order to recognize the functional monomers [41]. On the other hand, a crosslinker with more than 80% has a deleterious effect towards MIP performance. This might be due to the polymer that ends up blocking the binding sites, and furthermore, binding sites that are still accessible have a hard time removing templates, which in turn makes rebinding challenging [43]. However, the increase in crosslinker-solvent interactions results in mobile binding sites that reduces MIP recognition specificity, while the solvation propensity could be determined from the cross-performance linkers. \(N\),N-methylenebisacrylamide (BisAA) and pentaerythnitol triacrylate (PTA), for example, are superior to crosslinkers such as ethylene glycol dimethacrylate (EDMA) and divinylbenzene (DVB). PTA and BisAA solvate a lot of the popular solvents being used in synthesis and rebinding research. As there are fewer crosslinkers available to interact with, the general affinity of the MIPs become lower [44].  
However, in order for the template rebinding with the MIP to occur, a minimum of wettability is required. Unlike EDMA, DVB is too rigid and inadequately solvated to provide adequate recognition properties. DVB is also less thermally stable than EDMA, making it the most effective crosslinker for various template molecules [29; 45]. According to [PERSON] et al. [46], \"shape selectivity\" can be improved if traditional polymerization reagents are added with a functional crosslinker. A functional crosslinker was synthesized based on the steroidal template, which was 5-dihydrotestosterone, 17-hydroxy-5-androstan-3-one (DHT), of which also possess chemical interactions (Van der Waals stacking interactions) with the template in the pre-polymerization mixture. As a result, the synthesized polymer increases the number of binding sites and improves their homogeneity, making the use of such functional crosslinkers very remarkable.  
According to [PERSON] [47], the ratio of functional monomer to crosslinker is particularly important in this work because it controls the physical properties of the resulting MIP. Porogens are commonly used to improve the surface area of imprinted polymers and hence their capacity. One of the most important criteria in determining the surface area is the solubility of the template, monomer, and crosslinker. When phase separation causes the complex or polymer to precipitate, the surface area of the complex or polymer is reduced. Ifthe non-solvent forms an emulsion, it can cause cracks or pores, increasing the surface area. Using a solid porogen, such as a salt particle that can be dissolved and washed off, is an effective technique to enhance surface area. The surface area, pore size, and binding capacity of the resultant polymer, as well as the structure of the pre-polymerization complex, are all affected by the crosslinker's characteristics. The development of the pre-polymerization complex is driven by intermolecular forces between the template, monomer, crosslinker, and solvent, as proven by various computational investigations. As with porogens, this can result in phase separation, resulting in denser structures and reduced surface area. Because the strength of binding with molecules with similar qualities can be identical, this typically results in a variety of structurally distinct pre-polymerization complexes.