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|Title:||Development of thermoresponsive (polysulfone/polyacrylonitrile) - based membranes for bioseparation processes|
|Authors:||Viveiros, Raquel Filipa da Costa|
|Publisher:||Faculdade de Ciências e Tecnologia|
|Abstract:||In this work it is reported the synthesis of poly(N,N’-diethylacrylamide) (PDEAAm) and the preparation of temperature-responsive polysulfone-based blend membranes using green technologies. The synthesis of the temperature-responsive polymer PDEAAm was studied in supercritical carbon dioxide (scCO2) using different amounts of crosslinker (0 to 2 wt %) and surfactant (0 to 5 wt %). The products of the reactions were characterized by SEM, FT-IR, 1H-NMR, GPC, swelling and turbidimetric measurements. In all reactions, agglomerated polymeric particles were obtained. By increasing the crosslinker ratio in the polymer synthesis, the yield increased from 70 % to 89 %. The lower critical solution temperature (LCST) of synthesized polymers was investigated by turbidimetric measurements and varied in the range 33 - 35 ºC. Polysulfone/polyacrylonitrile (PS/PAN) blend membranes were produced by supercritical carbon dioxide induced phase inversion method. The PAN composition in the blend varied from 0 - 20 wt %. The membranes were characterized in terms of morphology (SEM), porosity (mercury porosimetry), hydrophilicity (contact angle measurements), transport properties (permeability) and mechanical performance (DMA). PS/PAN 9010 membrane showed to have adequate morphological and mechanical characteristics to be coated with temperature-sensitive hydrogels. Thus PS/PAN 9010 membrane was coated by in situ polymerization in scCO2 with two different thermoresponsive polymers, poly(N-isopropylacrylamide) (PNIPAAm) and PDEAAm. Coated membranes were characterized by SEM, X-ray photoelectron spectroscopy (XPS), mercury intrusion porosimetry, DMA, contact angle and water permeability measurements. Contact angle and permeability measurements were performed at 20 and 40 ºC, to investigate the on-off mechanism. Permeation experiments of bovine serum albumin (BSA) and lysozyme (LYS) solutions were performed to evaluate the performance and temperature-responsive behavior of coated membranes. While membranes coated with PNIPAAm presented similar BSA permeation profiles at temperatures below and above its LCST, PDEAAm coating showed a temperature-responsive behavior to PS/PAN 9010 membranes and selective permeation of proteins with different sizes (BSA and LYS).|
|Description:||Mestrado integrado em Engenharia Química e Bioquímica|
|Appears in Collections:||FCT: DQ - Dissertações de Mestrado|
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