SYNTHESIS OF POLYMER COMPOSITE PMMA-GRAPHENE AS SELECTIVE MEMBRANE FOR SODIUM CHLORIDE DETECTION BASED ON ELECTROCHEMICAL

• Main Author: Agung Suhendra, Muhamad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/50371
• Institution: Institut Teknologi Bandung

Fluids and electrolytes are needed to maintain a healthy body condition. Fluid and electrolyte balance in the body is one part of the physiology of homeostasis. In the human body, electrolytes are contained in blood, sweat, and urine where one of the main ingredients is sodium and chloride ions. The role and function of sodium ions are to help our bodies function properly, including as a regulator of fluid balance in the body, maintaining proper blood volume and pressure. The medical use of sodium ions is to determine the diagnosis of hyponatremia with the symptoms of nausea, headaches, confusion, and fatigue. Therefore, it is very important to develop a tool to detect it. Currently, various kinds of methods have been developed, one of which is using electrochemical sensors which are now widely developed and in demand because of their sensitivity, selectivity, low cost, and simple instrument use. Also, another advantage is that the response time is fast and can be minimized so that it is easy to carry out measurements on-site monitoring. In this research, Poly (methyl methacrylate) (PMMA) material is used as a polymer material that has good mechanical and optical properties and is used as a matrix of other materials to expand the surface which will then be mixed with grapheme material as fibers that fill the matrix, this is because graphene is a carbon material that is often applied in composite materials and has characteristics suitable for use as an electrochemical sensor. The choice of graphene is also based on its ability to increase the electroactive surface area and has good electronic properties. Also, it has a large and biocompatible surface area to volume ratio. Therefore, the combination of graphene and polymer-based PMMA is expected to become a new, more stable composite polymer material with the advantages of the respective properties of these materials. The synthesis of PMMA-Graphene composite polymer uses a mixing method with several steps. First of all, PMMA with a concentration of 0.25 M was mixed in a solution of Acetone then stirred using a magnetic stir for 120 minutes at a temperature of 800C until it looked homogeneous and DMF was added as an additive. After that, the graphene material with a concentration of 0.25 M was added to the solution which was then stirred again for 60 minutes at the same temperature and the last step was sonicated for 5 minutes. As for analyzing the structure, morphology, and composition of the material formed using Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS), to determine the effect of adding graphene material to PMMA polymers, Fourier Transformed Infrared (FTIR) is used and to determine the electrochemical properties. polymer composite and sensor performance used Cyclic Voltammetry (CV). SEM results show that the PMMA-Graphene composite polymer has a tubular structure indicated by the presence of a pore with a pore size of about ± 1 µM and this is due to the addition of graphene as a matrix fiber from PMMA so that it expands its surface. Furthermore, the FTIR results show that the addition of graphene increases the transmittance value while maintaining the PMMA position as the matrix, which can be seen from the peaks of the resulting vibrations having the same pattern. The electrochemical characteristics of PMMA-Graphene polymer composites have good CV results in the presence of oxidation and reduction peaks compared to GCE and PMMA. Besides, the CV results of the PMMA-Graphene composite polymer also showed a good electron transfer diffusion process after CV with a scan rate of 25 mV.s-1 - 300 mV.s-1. Finally, the PMMA-Graphene Sensor can detect and respond to sodium ions with an LoD value of 73.6 mM and can recognize and distinguish from other compounds even though it is not too significant in distinguishing NaCl and KCl.