Ali, Junaid (2024) Design and characterization of nanostructured gels containing inorganic nanoparticles. [Tesi di dottorato]

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Abstract

In this Ph.D. thesis, gel nanocomposites composed of nanoparticles and hydrogel polymers were prepared and characterized. Hydrogels based on cellulose and chitosan showed excellent softness, deformability, and biocompatibility properties, used in tissue engineering, contact lenses, wound dressing, drug delivery, and artificial muscles. Conventionally, they exhibit limitations in material performance, particularly in applications involving bioelectronics, optoelectronics, energy devices, and memory devices. Incorporating various nanomaterials into hydrogel media can enhance the performance and diversify the functions of hydrogels, resulting in hydrogel nanocomposites. The hydrogel nanocomposite, incorporating nanomaterials, enhances the properties and functionalities of the original hydrogel, preserving its inherent characteristics due to the nanoscale dimensions of incorporated particles. Firstly, hydrogel nanocomposites composed of zinc oxide nanoparticles and hydroxypropyl cellulose were prepared (section A). The fluorine-doped zinc oxide nanoparticles were synthesized and characterized, followed by the preparation and characterization of both physical and chemical gel composite. The purpose of the incorporation of nanoparticles was how they could affect and modify the gel composite properties. Starting with the physical gel, both the suspension and powder ZnO nanoparticles were used for composite preparation, and it was seen that the use of powder nanoparticles was more effective than the suspensions. So then chemical gel using a cross linker and powder nanoparticles was prepared. Finally, both were used for the photodegradation of amoxicillin (a contaminants in drinking water), where the physical gel exhibits better degradation activity compared with chemical gel. Also, it’s activity increases with the increasing the weight percentage of ZnO NPs. Secondly, a gel composite composed of silver (Ag) nanoparticles and chitosan was synthesized (section B). For the chitosan 1% wt. acetic acid was used as a solvent. Different weight percent of chitosan were tested, and 0.5% wt. was selected as the best one. The in situ synthesis of Ag-chitosan was performed using AgNO₃ as the precursor. Then its TEM images and UV spectra confirm the successful incorporation of Ag among chitosan-free chains.

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