Síntese e caracterização de dispersões aquosas à base de poli(uretano-ureia)s e seus nanocompósitos com diferentes cargas inorgânicas para aplicação como membranas para tratamento de água

• Autor(a) principal: Miranda, Gisele dos Santos
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/15644
• topic: Aqueous dispersions; nanocomposites; hydrophilic clay; carbon nanotubes; grapheme oxide; membranes; aqueous solutions permeation; Poli(uretano-ureia)s; dispersões aquosas; nanocompósitos; argila hidrofílica; nanotubos de carbono; óxido de grafeno; membranas; permeação de soluções aquosas; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA::POLIMEROS E COLOIDES

Novel non-pollutant materials based on waterborne poly(urethane-urea)s (WPUU) and respective nanocomposites (NWPUU) with inorganic nanoloads were synthesized aiming the obtainment of membranes adequate for separation of components present in aqueous solutions. The monomers employed in the formulations were: hydroxyl-terminated polybutadiene (HTPB), poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA) and isophorone diisocyanate (IPDI). Hydrazine (HYD) or ethylene diamine (EDA) were employed as chain extenders. The following inorganic compounds were added as nanoloads: hydrophilic montmorilonite clay (Clay Na+), simple wall carbon nanotubes (SWCNT) and hydroxyl-funcionalized graphene oxide (GO-OH). Formulations were developed targeting the production of materials with structural regularity, hydro- and organophilic appropriate characteristics, mechanical resistance and low elongation, minor swelling in water, low contact angle and adequate thermal and chemical resistances. Those are extreme important characteristics concerning to membranes applied in nanofiltration (NF) and inverse osmosis (IO) processes. In the formulations were varied: the length of flexible segment, employing polyethers (PPG) with two different molecular mass values; the proportion of PPG, HTPB and DMPA; the proportion between rigid and flexible segments (R NCO/OH); and the type of chain extender. Effective methods for nanoload dispersion were developed resulting in stable systems against sedimentation. The aqueous dispersions were characterized in terms of solid content (ST), apparent viscosity and average particle size. Cast films obtained from the dispersions were studied by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM), termogravimetry (TG), contact angle measurements, swelling in water tests and mechanical assays. Combined results pointed to the most promising materials for possible application as membranes for permeation of aqueous solutions, namely those formulations with: HTPB and DMPA higher contents, HYD as chain extender and R NCO/OH = 2.0. Based on these results, dispersions with 0.5% of nanoloads were synthesized. Two methods were tested to produce of the membranes: phase inversion, using different organic solvents, and casting in polyethersulfone (PES) support. The former were discarded because of the toxicity of the solvents. On the other hand, casting in PES resulted in composed dense membranes based on WPUU and NWPUU. The systems endured pressures up to 25 bar not showing any structural change, which confirmed the high mechanical resistance and structural regularity required for NF and IO processes. The results indicated the potential application of these materials in separation of aqueous micropollutants. In this work, the main parameters for optimization of casting method were detected in order to obtain low thickness composed membranes adequate to permeation processes