The project is experimental and focuses on the study of new families of polyelectrolytes (PE) by determining their phase diagrams as a function of variations in temperature, added salt or pH. This will be done optically (microscopy, diffusion) at CEA Saclay. Once the diagrams have been established, the phase separation (PS) of the PE solutions will be studied by confocal fluorescence microscopy to determine the growth laws and the scaling behavior of the separation. Phase separation is a dynamic process that will be initiated by temperature or concentration quenches, followed by the acquisition of time series images or correlation functions. It will lead to the formation of spatial structures that will be used to achieve an interconnected porous geometry. The results will be translated into guidelines for membrane manufacturing procedures that will be applied in Montpellier (European Institute of Membranes) to manufacture porous polyimide membranes of high mechanical and thermal resistance. Another side of the project will be to reproduce the experimental finding by a theoretical model able 1/ to explain the measured phase diagrams, 2/ to complete existing phase field theories for phase separation of neutral polymers to describe PE phase separation.