Environmental Engineering Reference
In-Depth Information
T
Complexation
Polymerization
-T
+T
SCHEME 20.1
General steps in the synthesis of IIPs.
species such as metals in an aqueous environment. The cavities in IIPs are fabricated such
that they contain adsorption sites characteristic of the target analyte in terms of shape,
structure, and morphology. The procedure to synthesize IIPs includes several steps that
generally involve the incorporation of a monomer, a cross-linker, an initiator, and a tem-
plate.
26-28
Generally, the IIP synthesis procedure involve three main steps: (i) complexation
of the template to a polymerizable ligand whereby the template interacts with the func-
tional monomer; (ii) polymerization of the complex formed in (i), which is followed by the
addition of the initiator and cross-linker that stabilizes the active sites so that the IIPs can
be regenerated and reused
29-31
; inally, (iii) the third step involves the removal of the tem-
plate after polymerization, and after this step the cavities or active binding sites that are
morphologically similar to the target analyte will now be available in the IIP.
32,33
Scheme 20.1
shows the process of IIP synthesis.
20.2.3.1 Monomers, Cross-Linkers, and Solvents for the Imprinting Procedure
20.2.3.1.1 Monomers
The selection of appropriate monomers for IIPs considers factors such that they should
have functional groups that will enhance the type of interaction with the template as well
as the polymer matrix.
34
Figure 20.2 presents examples of the mostly used monomer in the
synthesis of IIPs for the adsorption of various metals.
20.2.3.1.2 Cross-Linkers
In the synthetic processes for IIPs, the cross-linkers are normally in a higher proportion
in the inal polymer and actually the highly branched cross-linkers or those with high
molecular weight are known to result into stable active sites.
35
Figure 20.3 depicts cross-
linker molecules that have been reported in some applications.
