The　layer-by-layer　(LbL)　assembled　polyelectrolyte　multilayer　has　recently　been　recognized　as　a　new　class　of　promising　membrane　material　for　various　separation　uses.　However,　there　is　a　lack　of　understanding　about　the　influences　of　separation　mixtures　on　the　adsorbed　polyelectrolytes.　Therefore,　clear　understanding　on　it　would　be　very　important　for　the　design　and　application　of　a　type　of　new　functional　composite　membrane.　In　this　paper,　the　multilayer　of　weak　polyelectrolytes　polyethyleneimine　and　polyacrylic　acid　was　constructed　onto　a　hydrolyzed　hollow　fiber　polyacrylonitrile　support　membrane　under　a　negative　pressure　condition.　The　salt-,　pH-　and　oxidant-responsive　pervaporation　behaviors　of　polyelectrolyte　multilayer　membranes　were　evaluated　by　post-treating　with　sodium　chloride,　hydrochloric　acid,　sodium　hydroxide　and　sodium　hypochlorite　aqueous　solutions,　respectively.　The　pervaporation　performances　for　separation　of　ethanol/water　were　compared　before　and　after　post-treatments.　Scanning　electron　microscopy　and　atomic　force　microscopy　confirmed　the　microtopographical　changes　of　membrane　surfaces.　Optical　microscopy　was　also　used　to　real-time　observe　surface　morphologies　of　polyelectrolyte　multilayers　deposited　on　the　quartz　substrates.　Finally,　the　comparison　of　zeta　potential　values　of　inner　surface　before　and　after　post-treatment　also　demonstrated　the　changes　of　surface　electrical　property.　(C)　2010　Elsevier　B.V.　All　rights　reserved.