Ionic liquid-assisted the preparation of transparent cellulosic biocomposite films
(English) Interest in new environmentally friendly cellulose-based products has tremendously increased in recent years. Cellulose-based composites come in various forms and have potential applications in construction, automotive, packaging, sports, biomedical, and defense sectors due to their abunda...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/690374 |
| Acceso en línea: | http://hdl.handle.net/10803/690374 https://dx.doi.org/10.5821/dissertation-2117-405128 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria paperera Àrees temàtiques de la UPC::Enginyeria dels materials 67 620 |
| Sumario: | (English) Interest in new environmentally friendly cellulose-based products has tremendously increased in recent years. Cellulose-based composites come in various forms and have potential applications in construction, automotive, packaging, sports, biomedical, and defense sectors due to their abundance and versatility as a biopolymer. As a result, all-cellulose composites (ACCs) have gained significant research interest. ACCs are a class of biocomposites where the matrix is a dissolved and regenerated cellulose, while the reinforcement is undissolved or partly dissolved cellulose. This dissertation discusses a novel approach to developing highbarrier cellulose nanocomposite films with the assistance of an ionic liquid as a smart nanowelding agent to assemble nanometric cellulose structures. The aim of this study was focused on modifying regenerated cellulose by employing in situ ring-opening polymerization of e-caprolactone (CL) and L-lactide (LA) monomers, due to the higher amount of available initiating hydroxyl groups. “Grafting” copolymerization strategy can render the advantages of biofiber and impart polymer properties onto it, and the performance of biocomposites can be increased. Both polylactide and polycaprolactone as well as zinc oxide nanoparticles were used as reinforcements. The first part of the thesis is a review article that deals with the potential of prominent ionic liquids, with a focus on the selective and effective dissolution of cellulose, lignin, and hemicellulose from lignocellulosic biomass. It examines the factors influencing the solubility of biomass matrices and describes the ionic liquid-assisted production of biomass-based products of four different types: all cellulose-based composites and nanocomposites, all-wood composites, aerogels, and hydrogels. This review article provides useful information about the use of ionic liquids to develop products with a lesser impact on health and the environment, which can help researchers at large-scale pretreatment plants devise greener, more efficient processes. It also identifies research gaps with a view to improving future prospects and meeting challenges in ionic liquid technology. The second and third parts of the thesis were based on a green, efficient approach to rendering hydrophobic PCL (Poly e-caprolactone) and PLA (Polylactide) compatible with hydrophilic cellulose fibers by using the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim]OAc) in the presence of ZnONPs. The [Emim]OAc and ZnONPs were efficiently used to catalyze L-lactide and e- caprolactone ROP from the skeleton of cellulose as a backbone under mild conditions. The role of each component of the film was investigated with a view to optimizing water and oxygen barrier properties, strength, and UV-blocking capacity. Additionally, the study aimed to improve antioxidant activity and optical properties. The last part of this thesis involved designing a novel all-cellulose nanocomposite (ACNC) film. Ionic liquid also assisted in the green synthesis of lignin nanoparticles (LNPs) through a sonication method, allowing for even distribution without the need for additional reducing agents or stabilizers. ACNC films were produced using a partial cellulose dissolution process that trapped the synthesized LNPs. The study investigated the effect of LNP amount on the mechanical strength, antioxidant and antimicrobial activities, as well as UV, water vapor, and oxygen barrier properties of the prepared nanocomposite films. The findings demonstrate a simple and ecologically responsible method for producing bio-based nanocomposite films reinforced with lignin nanoparticles as entirely bioderived fillers for advanced applications. |
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