Synthesis and characterization of conductive hydrojel composites

Within the scope of the thesis, electrically conductive PAAm/Alg/CNC/rGO/PANI hydrogels containing reduced graphene oxide (rGO) in different amounts in its structure were synthesized. The polyacrylamide used in this hydrogel composite system is the main support material of the hydrogel. Sodium alginate (Alg) and crystalline nanocellulose (CNC) have been used to impart flexibility and stretchability to the hydrogel. poly(aniline) (PANI) has been used to provide electrical conductivity to the hydrogel. rGO has been used for electrical conductivity, mechanical strength and as a support material for aniline. The synthesis of hydrogel composite systems was carried out in two stages. First, eight PAAm/Alg/CNC/rGO hydrogels with different ratios of rGO in their structure were synthesized by solution radical polymerization method. Then, these hydrogels were immersed in aniline monomer solution and impregnated with aniline, and PAAm/Alg/CNC/rGO/PANI composites were produced by polymerization of aniline. Structural characterization of synthesized rGO was performed using XRD, EDX and mapping analysis techniques, and structural characterization of PAAm/Alg/CNC/rGO/PANI composite systems were performed using FT-IR and SEM analysis techniques. Swelling and mechanical tests were applied to all synthesized hydrogel composite systems to determine their equilibrium swelling values and mechanical strength. In order to measure the electrical conductivity of PAAm/Alg/CNC/rGO and PAAm/Alg/CNC/rGO/PANI hydrogel composites, electrical resistances at different frequencies were measured. Electrical conductivities of PAAm/Alg/CNC/rGO/PANI hydrogel composites at 25%, 50%, 75% and 100% swelling values were investigated due to the significant increase in electrical conductivity of hydrogel composites with the incorporation of PANI into the hydrogel structure. As a result of the electrical conductivity tests, it was determined that the hydrogel composition and the hydrogel swelling value had a high effect on the electrical conductivity. It has been determined that the synthesized hydrogel composites have the potential to be applied as strain sensors and ECG electrodes.