Study On Pvdf Membrane Modified By 2-acrylamido-2 Methylpropane Sulfonic Acid

Electrochemical gas sensor has a wide application in the field of environmental monitoring and safety production due to its small volume, low price and high accuracy. But this kind of sensors has a short life in practical use. To solve this problem and at the same time, to satisfy the requirement of smaller sensor's volume in some special fields, science researchers pay their attention on the solid electrolytes. Recently, Nafion membrane has been used as electrolyte in gas sensor. However, its conductivity is influenced by relative humidity (RH) largely, which results in unstable property in sensor. In addition, the cost of Nafion is high, which has been obstacles for commercialization of gas sensor. So, the main goal of the present work was to solve the problem of membrane water retention or find altermative membranes with good propertites and cheap price instead of Nafion membrane.In this thesis, we used poly (vinylidene fluoride) (PVDF) with excellent physical and chemical properties as foundation material, doping plain sodium silicate, grafting and blending 2-acrylamido-2-methylpropane sulfonic acid, which has stronge-acid, high heat stability, high conductivity and chemical stability. And a new solid electrolyte called modified poly (vinylidene fluoride) grafted onto a blended poly (2-acrylamido-2-methylpropane sulfonic acid) membrane (PVDF-g-PAMPS membrane) was prepared in order to improvement the membrane conductivity and water retention. The effect of the amount of solvent, initiator, drying conditions on membrane properties was investigated. The results showed that the content of N-methyl pyrrolidone is 20ml (that is, 0.20gPVDF/ml NMP); the content of ammonium persulfate is 0.4g/100ml; drying temperature is at 80oC and holding time is 4h.PVDF-g-PAMPS proton exchange membrane was characterized by IR,thermogravimetric analysis and SEM. The results showed the membrane surface smooth, the structure compact. AMPS had been grafted in the membrane and sulfonic acid groups distributed in membrane homogeneously. Water retention and conductivity of PVDF-g-PAMPS membrane were higher than Nafion117, and the mechanical properties of the membrance were characterized. Considering the costs, the conductivity, the mechanical properties, water retention of the membrane, and other properties, this new membrane has a good performance.