With the development of graphene-based composite, there is an increasing demand for graphene-based composite hydrogel and aerogel with adjustable mechanical properties to fit the requirement of various applications. The preparation of aerogel from produced hydrogel also opened a door for a wider selection of applications, such as electromagnetic interference shielding materials. This research investigated the formation of graphene/polymer and graphene/Ni- ferrite nanoparticles hydrogels. In the case of graphene/polymer hydrogel formation, five different polymers with varying functional groups were mixed with graphene oxide (GO) by adjusting the ratio of graphene to polymer. The results showed that the formation of reduced graphene oxide (rGO) hydrogels depended on the properties of graphene at different reduction conditions, the original properties of the polymer and the concentration of metal precursor. The study demonstrated that graphene/polymer hydrogels have adjustable mechanical and electrical properties, making them suitable for a wide range of applications. Moreover, this thesis provided the systematic study of the combination mechanism between polymer functional groups and graphene sheets, where graphene sheets were acting as physical crosslinker to wrap the polymer chain together. In the case of graphene/Ni-ferrite hydrogel formation, the study investigated the efficiency of different reducing agents and the influence of the precursor's amount on the nanoparticles. The optimal ratio of precursor and reducing agent was defined. A stable rGO/Ni-ferrites hydrogel film was formed. The study also provided insights into the efficiency of different reducing agents and the influence of the amount of precursor and reducing agent on the morphology of the synthesized nanoparticles. Compared to the current study on graphene aerogels for EMI shielding applications, the synthesized graphene-based aerogel film in this research has a thickness of only 2mm and adjustable porosity. The EMI properties of pure rGO aerogel and rGO/polymer aerogel films were analyzed, revealing that the electromagnetic properties of rGO/Ni-ferrite nanoparticles were superior to those of rGO/polymer aerogel films. This difference in performance can be attributed to the significant dielectric loss and magnetic loss exhibited by rGO/Ni-ferrite aerogels. In summary, the research sheds light on the properties and synthesis of graphene/polymer and graphene/Ni-ferrite hydrogels, paving the way for further research and development in these areas. The findings of the study contribute to a better understanding of the mechanism of rGO hydrogels formation, the efficiency of different reducing agents, the influence of the amount of precursor and reducing agent on the morphology of the synthesized nanoparticles. More importantly, the results provide several options to adjust the mechanical properties and electromagnetic characteristics of graphene-based hydrogels, which is beneficial for choosing materials for different applications.
Preparation of Graphene-based Composite of Hydrogel and Aerogel
Luan, D. (Author). 21 Jun 2023
Student thesis: Phd