Publicação
NATURAL DEEP EUTECTIC SOLVENTS AS GREENER ALTERNATIVES FOR MEMBRANE PREPARATION
| Resumo: | Decades of persistent efforts to uphold the principles of green and sustainable chemistry and engineering have resulted in the development of numerous solvents intended to replace the industrially (or traditionally) used toxic, volatile, and harsh counterparts. However, achieving similar or enhanced level of performance by alternative solvents is still a challenge. Membranes can be engineered within a scientific and holistic framework, wherein the use of green solvents plays a pivotal role by minimizing environmental impact and supporting sustainable targets. In the past decade, hydrophobic deep eutectic solvents (DESs) have garnered considerable attention as green and environmentally benign alternatives, attributed to their facile synthesis, 100% atom economy, low cost, minimal toxicity, biodegradability, and remarkable tunability. As a step forward, this work explores the role of novel natural hydrophobic DESs to enhance the green metrics associated with polymeric membrane preparation. In the initial case-study, the hydrophobic DESs were dispersed into a polymer containing continuous phase to formulate DESs-in-water emulsions. Subsequently, the resulting emulsion systems were cast to form emulsion-based membranes by solvent evaporation. Owing to the intrinsic properties of the components of the natural DESs, these membranes exhibited enhanced antioxidant activity, indicating potential for food packaging. In the following study, natural hydrophobic DESs were used for the first time to prepare eutecto gel-based membranes by photo-initiated polymerization to form crosslinked networks. The resulting membrane matrix exhibited stability alongside tunable thermal and mechanical characteristics. In a separate study, hydrophobic DESs were incorporated into ethyl cellulose-based membranes by solvent evaporation method. The inclusion of DES provided a critical plasticizing effect while preserving the membranes’ barrier properties against water vapor and individual gases. While the previous studies focused on the role of hydrophobic DESs as active agents in membranes, the final study explored DESs as alternative green solvents able to solubilize polymers. Polyimide dope solutions in DES were successfully prepared and cast into flat-sheet membranes by non-solvent induced phase separation. The formation of a spongy asymmetric membrane with dense skin layer showcased high gas separation performance. Collectively, these studies establish hydrophobic DESs as versatile, green processing agents that enable the design of functional membranes with tailored physicochemical and separation characteristics, thereby advancing sustainable membrane technologies. |
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| Autores principais: | Alke, Bhavna |
| Assunto: | Sustainability Green solvents Hydrophobic deep eutectic solvents Membrane formation |
| Ano: | 2026 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Decades of persistent efforts to uphold the principles of green and sustainable chemistry and engineering have resulted in the development of numerous solvents intended to replace the industrially (or traditionally) used toxic, volatile, and harsh counterparts. However, achieving similar or enhanced level of performance by alternative solvents is still a challenge. Membranes can be engineered within a scientific and holistic framework, wherein the use of green solvents plays a pivotal role by minimizing environmental impact and supporting sustainable targets. In the past decade, hydrophobic deep eutectic solvents (DESs) have garnered considerable attention as green and environmentally benign alternatives, attributed to their facile synthesis, 100% atom economy, low cost, minimal toxicity, biodegradability, and remarkable tunability. As a step forward, this work explores the role of novel natural hydrophobic DESs to enhance the green metrics associated with polymeric membrane preparation. In the initial case-study, the hydrophobic DESs were dispersed into a polymer containing continuous phase to formulate DESs-in-water emulsions. Subsequently, the resulting emulsion systems were cast to form emulsion-based membranes by solvent evaporation. Owing to the intrinsic properties of the components of the natural DESs, these membranes exhibited enhanced antioxidant activity, indicating potential for food packaging. In the following study, natural hydrophobic DESs were used for the first time to prepare eutecto gel-based membranes by photo-initiated polymerization to form crosslinked networks. The resulting membrane matrix exhibited stability alongside tunable thermal and mechanical characteristics. In a separate study, hydrophobic DESs were incorporated into ethyl cellulose-based membranes by solvent evaporation method. The inclusion of DES provided a critical plasticizing effect while preserving the membranes’ barrier properties against water vapor and individual gases. While the previous studies focused on the role of hydrophobic DESs as active agents in membranes, the final study explored DESs as alternative green solvents able to solubilize polymers. Polyimide dope solutions in DES were successfully prepared and cast into flat-sheet membranes by non-solvent induced phase separation. The formation of a spongy asymmetric membrane with dense skin layer showcased high gas separation performance. Collectively, these studies establish hydrophobic DESs as versatile, green processing agents that enable the design of functional membranes with tailored physicochemical and separation characteristics, thereby advancing sustainable membrane technologies. |
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