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Synthesis and characterization of dihydroxyl-functionalised PAMAM dendrimers for binding of heavy metals
Author
Loo, Hui Hui
Supervisor
Chu, Chit Kay
Abstract
In this study, ammonia-core poly(amidoamine) (PAMAM) dendrimers are synthesized via the divergent approach involving a two-step reaction sequence. Half-generations PAMAM dendrimers are obtained by Michael addition of ammonia (1 mole) to methyl acrylate (5 moles) and are purified by column chromatography. Full-generations PAMAM dendrimers are obtained by exhaustive amidation of half-generation PAMAM dendrimers (1 mole) with excess ethylenediamine (50 moles). All PAMAM dendrimers are in the form of an oil and are obtained in good yield. 'H NMR, elemental analysis and IR provided analytical data consistent with the structures of the PAMAM dendrimers. Functionalisation of G1 PAMAM dendrimers is based on Schiff Base reaction and capitalizes on the addition of 3,4-dihydroxybenzaldehdye, to the dendrimers, leading to the condensation of water, formation of C=N links and twelve peripheral hydroxyl groups are formed on the surface of the first generation of the dendrimer. The yellow powder resulting from the reaction is soluble in water. 'H, "C NMR and IR show the imine bond, which is the salient feature in the characterization of the compound. Preliminary investigations obtained from using standard lead solution as the eluent and silica gel mixed with the dihydroxyl-functionalised G1 PAMAM dendrimers show a significant decrease of about 95% in the lead concentration in the presence of the dendrimers. This outcome demonstrates the potential of using dihydroxyl-functionalised dendrimers as a metal trap.
Date Issued
2004
Call Number
TP1180.D45 Loo
Date Submitted
2004