Development of molecularly imprinted polymers using supercritical fluid technology

Dissertação para obtenção do Grau de Doutor em Química Sustentável

Within the last decade, the interest in molecularly imprinted polymers (MIPs) has strongly increased because of their promising applications in separation processes, drug delivery, biomimetic sensing and catalysis. This thesis reports the development of MIPs using supercritical fluid technology as a viable and greener alternative to the synthesis and processing of these molecular recognition polymers. The affinity to the target molecule was introduced by means of non-covalent and semicovalent molecular imprinting and the performance of the materials was evaluated in specific applications of drug delivery, chiral chromatography and adsorption of environmental pollutants. The influence of experimental parameters, such as crosslinking degree, functional monomer nature and template: monomer ratio, on molecular recognition was investigated. The results show that it is possible to tune the affinity of the polymers by optimizing the imprinting reactional mixture. MIPs show higher loading capacities and affinity constants to the template molecule, both in supercritical and aqueous environments. Hybrid membranes were prepared by a scCO2-assisted phase inversion method, showing that imprinted particles can be immobilized into porous structures introducing affinity to the materials. Further, HPLC experiments attested that the synthesized MIPs have high selectivity towards the template, as an enantiomeric differentiation was achieved when the racemic mixture was loaded into the imprinted polymeric stationary phase. The work developed in this thesis contributes to the consolidation of scCO2 as alternative solvent and demonstrates the feasibility of synthesizing clean, easy-to-make and ready-to-use molecular recognition polymers using sustainable technologies.

Fundação Ciência e Tecnologia - grant SFRH/BD/31085/2006 and projects PTDC/QUI/66086/2006 and PTDC/QUI-QUI/102460/2008