An amphiphilic comb-like polysiloxane(ACPS) containing polyether side chains is presented as the modification reagent in preparation of hydrophilic porous poly(vinylidene fluoride)(PVDF) membrane via phase inversion process.The effects of blending ACPS on the morphology

crystallinity

mechanical properties

chemistry structure

hydrohilicity and filtration performance of porous PVDF membranes as well as the stability of ACPS in phase inversion process were investigated.Basing on the membrane forming kinetics displayed from measuring the light intensity transmitted through the membrane

it was found that the addition of ACPS would lead the delayed demixing between casting solution and coagulating water during the phase inversion process.The instantaneous demixing resulted in the formation of membranes with "fingerlike" macrovoids in the sublayer

whereas the delayed demixing yieded membrane structure containing a "spongelike" sublayer.And thus

the solidified PVDF membrane with larger pore size was obtained with increasing the content of PVDF in casting solutions.Furthermore

the introduction of ACPS into the membrane system increased the PVDF crystallineity because the delayed demixing permitted a longer crystallization time in membrane formation.Surface and bulk chemical compositions of blend membranes were measured respectively to study the reservation and the enrichment of ACPS molecules in the membrane formation proces.It was revealed that the O/F ratio of membrane bulkwas almost the same as that of the corresponding casting solution

which obviously indicated the higher reservation of ACPS inmembrane formation proces.The fact that the O/F ratio in membrane surface layer was much higher than that in membrane bulk proved the enrichment of ACPS on surface.The reason for such surface enrichments could be explained as follows.In phase inversion process

the ultra-hydrophilic poly(ethylene oxide)side chains in ACPS tended to moving out of the membrane and disslving into the coagulation bath.However

the ACPS molecule as a whole strongly entwisted with PVDF chains is not able to dissolve into the coagulation bath.As a result

the ACPS molecules enrich in the final surface layer

and the hydroiphilic poly(ethylene oxide)side chains stretch toward the outside of the membrane surface.In fact

such enrichment also occurred in wall surface of pores inside the membranes.via Supposing a schematic model

this explanation was clearly illustrated.The enrichment of ACPS with PEO side chain stretching trends endows the membrane with excellent hydrophilicity both for membrane surface and wall of pores inside membrane

which was fully proved by measurements of water contact angle.As the ACPS molecules were greatly entwisted by PVDF chains

the ACPS could be reserved in membranes stably and thus result in the reliable hydrophilic stability for PVDF membranes.Such stability is very important and greatly expected while the filtration performance in practical application of final PVDF membrane is considered.In this work

this stability was also approved clearly through continous shake test(in 60℃ water) simulating the application process.For prepared ACPS/PVDF blend membranes without further hydrophilication treatment(e.g.coated by glycerol

ethanol or other surfactant)

the water flux was relative large while the retention property was controlled properly.Form the observed results it is concluded that the ACPS should be contributed to the potenial candidate materials for high performance filtration membranes.