The aim of this work is the preparation of porous polymeric membranes for liquid
separations stable in organic solvents, high temperature and/or extreme acid or basic
conditions. Polymeric membranes with these properties could replace more traditional and
energy-expensive separation processes like distillation, competing with ceramic
membranes due to their easy processability and scalability.
A limited library of polymers have been successfully used for decades in water-based
applications. They are however unstable in organic solvents without an additional
treatment, which is usually a crosslinking reaction. In this dissertation different highperformance
polymeric membranes and crosslinking strategies are presented and
discussed, allowing their use in harsh environments.
We present for the first time the preparation of porous membranes using poly(oxindole)
derivatives. These polymers were prepared by superacid catalyzed polyhydroxyalkylation,
which is a novel one-pot, room-temperature, metal-free polymerization method. The
obtained polymers were fully characterized and then manufactured into membranes by the
non-solvent induced phase separation method. The crosslinking of these membranes was
achieved by different protocols. First, we reacted the oxindole group in the polymer
backbone with a variety of dibromides of different chemical structure. Secondly, we
incorporated a propargyl side group, followed by a crosslinking in hot glycerol. Moreover,
the strategy of crosslinking using propargyl as pendant group was successfully
demonstrated in membranes made of poly(benzimidazole) and poly(triazolebisphenol-AF).
And thirdly, we prepared membranes from hydroxyl-functionalized poly(oxindole), and
conducted a controlled thermal oxidation, which resulted in the crosslinking by phenoxy
radicals. In each case, the resulting membranes achieved insolubility in polar aprotic
organic solvents, high resistance in acid medium and had high decomposition temperatures.
In each case, the resulting membranes achieved not only insolubility in polar aprotic
organic solvents and resistance to acid media but also showed high decomposition
temperatures. Finally, we demonstrated for the first time the preparation of porous
membranes based on recycled poly(ethylene terephthalate) plastic bottles and their
potential application for separations in an organic solvent medium.
|Date of Award||Nov 2019|
|Original language||English (US)|
- Biological, Environmental Sciences and Engineering
|Supervisor||Suzana Nunes (Supervisor)|
- Organic Solvent
- Thermal Resistant