Perpustakaan Digital ITB

At present most of the world’s energy supply come from fossil sources. Environmental impacts of fossil fuel usage are now considered to be not environmental friendly. Production of CO2 from human activities has been causing the earth temperature to rise and indirectly affected the climate. Recently, the development of alternative clean energy and energy conversion are the major project to solve that problem. The development of alternative clean energy and energy conversion based on liquid electrolyte as ion conductor has been known to cause corrosion problems. Therefore, there is a demand for solid proton conductor based on solid polymer. In this research, sulfonated polysulfone (SPSf) cation exchange membranes, which were prepared by sulfonation of polysulfone (PSf) using chlorosulfonic acid in chloroform, were evaluated as Polymer Electrolyte Membrane (PEM). This work consists of three main stages, namely sulfonation of polysulfone, membrane preparation and its characterization. The effects of inorganic filler, TiO2 nanoparticles on the properties of PSf/SPSf/TiO2 composite membrane were also investigated. The sulfonation was done by varying the concentration of chlorosulfonic acid from 5 to 15% v/v in chloroform and nitrogen atmosphere. Membranes preparation were done using phase inversion method by casting the dope (casting solution) onto clean glass. The dope was made by dissolving the polymer (PSf and SPSf) in DMAc (dimethylacetamide). SPSf powder and the resulting membranes were characterized using 1H NMR and FTIR spectroscopies, acid base titration, thermal and mechanical analysis as well as morphologies surface and cross section by SEM (Scanning Electron Microscope) and electrochemical analysis. It was found that the sulfonation induces a decrease in the glass transition temperature (Tg) of polymer which indicate the occurrence of polymer main chain degradation. Sulfonation of PSf with 5% of chlorosulfonic acid achieved high yield (94.53%), but higher concentrations (10 and 15%) may cause chemical degradations which make the polymer soluble in water. High degree of sulfonation caused the polymer to be hydrophilic and the polymer chain shortening caused by the degradation make the polymer-water interaction easier, thus the polymer is soluble in water. Therefore, sulfonation product from 10 and 15% of chlorosulfonic acid can’t be uses as PEM materials. The presence TiO2 increased the mechanical stability and also the membranes ion conductivity. The increase of inter chain interaction and the interaction between polymer and TiO2 particles resulted in an increased membrane mechanical stability. The presence of TiO2 in membrane structure also facilitated ion movement from anode to cathode which causes an increasing of membrane ion conductivity. Higher concentration SPSf (10%) in the membrane composition results in brittle membranes. Hydrophilic-hydrophobic inters polymer chain results crack-like area in the membrane surfaces, which caused in decrease of membrane elasticity. Impedance data showed the presence of TiO2 results in a decrease of membranes resistance or increase of membrane conductivity. Addition of inorganic filler can improve ion transport through the membrane and increase the membrane conductivity. Higher concentration of SPSf (10%) resulted in decreasing membranes resistance in compared to PSf membrane. Composite membrane with composition PSf/SPSf/TiO2 10/10/5 produces membrane which has highest ion conductivity. Electrochemical performance, thermo-mechanical stability and low cost fabrication the resulting membranes are attractive as PEM material. However, modification still needed to improve the membrane performance.