A supercritical carbon dioxide (ScCO

2

) assisted phase inversion was developed to produce microporous poly(vinylidene fluoride) (PVDF) membranes whose morphology characteristics arise from both liquid-liquid demixing and solid-liquid demixing (crystallization). This result was confirmed by Fourier transform infrared spectroscopy (FTIR)

from which both

α

and

β

crystals were found. As revealed by contact angle experiment

the PVDF membranes prepared via ScCO

2

assisted phase inversion were more hydrophobic compared with the control membrane produced via conventional immersion-precipitation technique. In particular

the sample with 15 wt% PVDF prepared at 45 ℃ and 13 MPa exhibited a contact angle of 142°

which was mainly caused by the multilevel micro- and nano- structure. The effects of polyethylene glycol (PEG)

polyvinyl pyrrolidone (PVP) and lithium chloride (LiCl) on the structures and crystal form were investigated. PVP promoted the formation of

α

phase crystal form

while PEG boosts the evolution of

β

phase. LiCl restrained the crystallization degree of PVDF membrane under ScCO

2

.