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Keywords: RAFT polymerisation, polyHIPEs, hypercrosslinking, porous polymers, porosity
Published in DKUM: 10.05.2024; Views: 156; Downloads: 17
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Abstract: PolyHIPEs are highly porous polymers with an interconnecting porous structure. They have found usage in the removal of pollutants, water clean-up, oil spill removal, catalysis, controlled release of active compounds, wound dressing and tissue engineering. The wide applicability of polyHIPEs is possible through their inherent porosity and chemical diversity. The aim of this dissertation was to increase the chemical diversity of polyHIPEs, develop an efficient method for the synthesis of polyHIPE beads and to use natural resources for the synthesis of polyHIPEs, subsequently, paving the pathway to more sustainable synthetic procedures. PolyHIPEs tend to have poor mechanical properties, therefore, it was crucial to investigate the influence of the internal phase volume, initation type (photo vs thermal) and monomer functionality on the mechanical and morphological properties of thiol-ene polyHIPEs. The results show that the main factors influencing the morphological and mechanical properties are the monomer structure and the internal phase volume. Besides the inherent porosity and chemical versatility typical of polyHIPEs, they can also be produced in various shapes, e.g., monoliths, membranes and beads. Therefore, the dissertation also focuses on the synthesis of polyHIPE beads. The polyHIPE beads were produced through the usage of water-in-oil-in-water (W/O/W) multiple emulsions. To enable the synthesise of open porous polyHIPE beads, thiol-ene polymerisation was combined with photopolymerisation to guarantee a rapid polymerisation prior the break-down of the multiple emulsion. Consequently, it was possible to synthesise polyHIPE beads. The first study showed that by altering the thiol to acrylate ratio in favour of the acrylate the degradation rate of the synthesised polyHIPE beads gets reduced. Additionally, it was demonstrated that the beads can be readily functionalised with allyl amine and used for the adsorption of methylene blue (12.0 mg/g in 24 hours). The next study combined polyHIPE beads with magnetic nanoparticles (MNPs) to produce magnetic polyHIPE beads which were used for the removal of Pb2+. To produce the magnetic polyHIPE beads, magnetic nanoparticles (MNPs) were added to the organic phase. The MNPs get incorporated into the polymer-network after the polymerisation, therefore, forming magnetic polyHIPE beads. The MNPs were shown to influence the morphology and the size of the beads. Additionally, the polyHIPE beads were shown to remove up to 97.0 % of Pb2+ after 24 hours from a 2.9 mg/L solution of Pb2+. In the last study related to the synthesis of polyHIPE beads, functional polyHIPE beads were produced and then functionalised to enable the binding of the enzyme invertase. These beads were then utilised for the hydrolysis of sucrose. The conversion of sucrose to glucose and fructose was 100% after 60 minutes for the polyHIPE beads, while the conversion for non-porous beads was only 6.5%. The last part of the thesis focused on more sustainable/natural approaches to polyHIPE synthesis. The first study utilised limonene as a replacement to conventional solvents (e.g., cyclohexane) in the production of O/W HIPEs and the polymerisation thereof into polyHIPEs. It was shown that limonene can be used as an efficient replacement in the production of polyHIPEs. The next study used natural resources (terpenoids) which were modified to contain polymerisable units, which were used for the synthesis of terpenoid-based polyHIPEs. The synthesised monomers were then crosslinked with 5 and 10 mol. % TMPTA to form polyHIPEs, consequently producing porous polymers. The last study in this thesis used the terpenes limonene, carvone and myrcene to produce bio-based polyHIPEs by utilising multifunctional acrylates (PETA and TMPTA) as the comonomers. This study demonstrates that it is possible to prepare polyHIPEs from commercially available terpenes, therefore, moving the field of polyHIPEs into a more sustainable direction.
Keywords: HIPE, PolyHIPE, Multiple Emulsions, Functional polyHIPEs, Natural Polymers, Terpenes
Published in DKUM: 08.12.2023; Views: 456; Downloads: 80
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Abstract: A new class of polyHIPE materials has been prepared using high internal phase emulsions (HIPEs) with monomers in both phases. Resulting materials, namely hybrid polyHIPE materials, are obtained consisting of hydrophobic matrix (consisted of styrene cross-linked with DVB or dicyclopentadiene) filled with hydrophilic polymer gel (polyacrylic acid or polyNIPAM) and exhibit morphology changes according to pH and temperature of the surrounding medium. Our focus with regards to the production of hybrid polyHIPE materials was the responsiveness of such materials used for flow control. This property is beneficial for controlling the flow of the solution through the monolithic polymers. Furthermore, polyHIPE materials have also been prepared by using ring opening metathesis polymerisation of monomers, such as dicyclopentadiene and norbornene. Obtained materials have Young’s moduli in the range of hundred times higher than standard polyHIPE materials with the same level of porosity which represents a very important improvement in the development of highly porous cellular polymeric materials.
Keywords: emulsions, high internal phase emulsions, polymers, polyHIPEs, hybrid, hybrid polyHIPE materials, ROMP, flow-through, styrene, DVB, acrylic acid, NIPAM
Published in DKUM: 04.05.2011; Views: 3490; Downloads: 328
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