Estudo do método de obtenção de membranas assimétricas de polietersulfona contendo complexos de polieletrólitos

Abstract

Compared with traditional separation methods, polymeric membranes have low operation cost, fast separation rate and versatility. One interesting way of changing membrane properties is mixing additives into the polymeric matrix. Polyelectrolytes complexes (PECs) (polyelectrolytes combined via electrostatic interaction) are a good material for that due theirs hydrophilicity, tunable surface charge, stable structures and insolubility in common solvents. Based in this context, inversion phase membranes containing PECs were obtained through three different methodologies: in situ, post crosslink and simultaneously crosslink. The chosen polyelectrolytes were 4-fluorophenyl sulfone terminated poly(diallylpiperidinium hexafluorphosphate) (PDApipPF6) and sulfonated poly(ethylene terephthalate) (SPET). The polymeric matrix used was polyether sulfone, known for its good mechanical strength and high temperature stability. Analysis by fourier transform infrared spectroscopy confirmed the presence of SPET in the PEC membranes, while the presence of PDApipPF6 was confirmed by positives values of zeta potential. Scanning electron microscopy images of the cross-section of the membranes were similar and showed asymmetric structure consisting of a dense skin and porous sub-layer. The increase of water vapor permeability and the decrease of water contact angle of the PEC membranes indicated that the presence of the complexes alters the membranes’ hydrophilic profile. Differences in the curves of the thermogravimetric analysis showed that depending on how the PECs are obtained, the interaction between the PELs changes, which produces membranes with different thermal behaviors. The results of filtration and adsorption of remazol red also varied with the methodology.