Multifunctionalization of PTFE membrane surface for biofouling resistance and oil/water separation performance improvement

Abstract

Polytetrafluoroethylene (PTFE) is considered as one of the most promising membrane materials for oil-water separation, mainly because of its excellent chemical and mechanical stability. But its inherent strong hydrophobicity, which can cause the membrane easy fouled by bacteria, limits the application of PTFE membrane. We designed a new surface modification approach, through which hydrophilic and antibacterial PTFE membranes can be fabricated conveniently by combining polymerized dopamine (PDA) and thiolactone chemistries. A copolymer (P(DMAEMA-co-TlaAm)) containing thiolactone and tertiary amine moieties were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization and attached onto the PDA coated PTFE membrane surface, together with glucosamine, via the thoilactone chemistry. Due to efficient glycosylation, the membrane exhibits great hydrophilicity. Water contact angle of the membrane surface dropped from 123° to 13°. Pure water flux of the membrane reached 2490 L m−2 h−1 bar−1, which is 2.7 times that of the original membrane. Also, the separation efficiency of the iso-paraffin emulsion reached 97.5 % at a membrane flux of 90 L m−2 h−1 bar−1. Notably, in addition to the hydrophilicity provided by glucosamine, the modified membranes also showed decent antibacterial property because of the introduction of tertiary amine groups. The bacteria inhibition rate against Staphylococcus aureus reached 99 %.