Studies of the Monomer-Template Solution Structures

To what extent do the solution complexes formed between the monomer and the template in solution reflect the architecture of the polymeric binding sites This question is important, since a thorough characterisation of the monomer-template assemblies may assist in deducing the structure of the binding sites in the polymer and thus have a predictive value. 

As discussed in Section 5.5.3.1., the potential for a given monomer-template pair to produce templated sites can be predicted by measuring the stability constants, e.g. by spectroscopic techniques, in a homogeneous solution mimicking the 

RECOGNITION BY POLYMERS IMPRINTED WITH 06-METHYL-GUANINE (06MG) AND 06-ETHYLGUANINE (06EG) 

The polymers were evaluated using either acetonitrile/acetic acid/ water 92.5/5/2.5 (v/v/v) or acetonitrile as mobile phase. 10 nmol of solute were injected in 10 /rl of the mobile phase. 

ASSOCIATION CONSTANTS FOR COMPLEXES BETWEEN CARBOXYLIC ACIDS AND NITROGEN BASES IN APROTIC SOLVENTS AND CORRESPONDING ASSOCIATION CONSTANTS AND SITE DENSITIES FOR BINDING OF THE BASE TO A MIP 

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In the self-assembly approach to molecular imprinting (Fig. 7.1) studies have indicated that the solution structure of the monomer-template assemblies defines the subsequently formed binding sites.3 In other words, the amount and quality of recognition sites in the MIP depends on the number and strength of specific interactions occurring between the template and the monomers in the prepolymerisation mixture (Fig. 7.4). These are in turn influenced by the quality of the solvent, cross-linking monomer, temperature, and pressure used in the polymerisation. 

Conducting polymers are usually synthesized from the appropriate monomers by either chemical or electrochemical oxidative polymerization. Electrochemical polymerization is preferred for better penetration inside the nanopores. Polypyrrole (PPy) is one of the most important and extensively studied conducting polymers (Moreno et al. 1999 Vrkoslav et al. 2006 Lewis et al. 1997 Akundy and Iroh 2001). The deposition of PPy into PSi templates could be achieved by the electrochemical oxidation of pyrrole monomers at constant current or potential in the acetonitrile solution containing tetrabutylammonium perchlorate as supporting electrolyte. Typical potential (E-t) and current transients (i-t) recorded during the deposition of PPy into mesoporous silicon templates are shown in Fig. 3. The mechanism of polymer infiltration into the pores is of major importance in order to obtain the desired structures and control the final morphology. 

Hilal et al. [25] studied the surface structure of molecularly imprinted poly(ether sulfone) membranes (called MIP membranes) by AFM and quantified the pore size and the surface roughness. They modified PES microfiltration membranes with a normal pore diameter of 0.22 j,m and a thickness of 150 (Am (Millipore). First, the membranes were coated with photoinitiator by soaking them in a 0.25 M solution of benzoin ethyl ether (BEE) in methanol and then immersing them in a mixture of 80 mM trimethyl propane trimethacrylate (TRIM), 40 mM 2-hydroxyethyl methacrylate (HEMA), and 2 mM adenosine 3 ,5 -cyclic monophosphate (cAMP) in an ethanol-water mixture (70 30 vol.%). Thereafter, the membranes were exposed to a B-100 lamp of relative radiation intensity 21.7 mW cm at 355 nm. Membranes with different modifications were obtained using various UV exposure times. The residual nongrafted polymer, monomer, initiator, and the template were extracted with methanol. After drying, the degree of modification (DM) was calculated from the... 

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