The　present　investigation　revealed　how　the　surface　morphology　and　hydrophobicity　of　polyvinylidene　fluoride　(PVDF)　membranes,　which　were　prepared　via　a　vapor-induced　phase　separation　(VIPS)　method,　were　affected　by　the　exposure　time.　The　mass　variation　of　the　cast　film　was　recorded.　Membrane　morphologies　were　observed　by　scanning　electron　microscopy　(SEM)　and　thermal　behaviors　of　membranes　were　examined　by　differential　scanning　calorimetry　(DSC).　Wide　angle　X-ray　diffraction　(WAXD)　was　employed　to　analyze　the　crystalline　structures　of　the　overall　membranes　and　the　surface　layers.　The　results　showed　that　different　membrane　morphologies　and　hydrophobicities　could　be　obtained　by　changing　the　exposure　time.　A　long　exposure　time　facilitated　the　crystallization　process,　resulting　in　the　formation　of　a　porous　skin　and　particle　morphology,　which　increased　the　hydrophobicity　of　the　surface.　A　short　exposure　time　favored　the　formation　of　a　digitate　macrovoid　and　dense　skin　resulting　from　liquid-liquid　phase　separation　in　the　immersion　process,　which　reduced　surface　hydrophobicity.　The　water　permeate　flux　in　vacuum　membrane　distillation　was　greatly　affected　by　the　membrane　porosity　and　surface　hydrophobicity.　(C)　2012　Elsevier　B.V.　All　rights　reserved.