Economical production of PVDF-g-POEM for use as a blend in preparation of PVDF based hydrophilic hollow fibre membranes

A simple and environmentally friendly method for purification of graft copolymers of poly(vinylidene fluoride) with poly(oxyethylene methacrylate) (PVDF-g-POEM) synthesised via atom transfer radical polymerisation (ATRP) has been introduced. This method involved fewer steps and use of water as a purification solvent instead of the previously suggested mixture of methanol/petroleum ether, which is highly volatile, toxic and expensive. The characterisation of the purified copolymer indicated that the PVDF-g-POEM with very high purity can be obtained using water as a precipitator and a purifier. This suggests that the new method is more suitable for use in industrial scales as it is more economical. Also, because working and recycling volatile solvents are difficult, this method seems to be easier to apply and more environmentally friendly. The purified copolymer was used as a blend to produce hydrophilic PVDF hollow fibres and the obtained hollow fibres from blending 5 wt.% of the copolymer in the PVDF spinning dope solution showed a pure water flux of approximately 130.5 (L m−2 h−1) with the molecular weight cut off (MWCO) of 200 (kDa). The test for the flux recovery after fouling by BSA and subsequent washing with water showed a recovery higher than 95%, indicating the hydrophilic nature and antifouling characteristics of the prepared hollow fibres.

► A simple and environmentally friendly method for the purification of PVDF-g-POEM is employed. ► The purified copolymer was used as a blend to produce hydrophilic PVDF hollow fibres. ► The blend membrane shows water flux of approximately 130.5 (L m−2 h−1) with MWCO of 200 (kDa).