Manipulating spherical and polar structure of polyvinylidene fluoride (PVDF) piezocatalytic membrane by thermally induced phase separation

PVDF (Polyvinylidene Fluoride) membrane separation is a classic technique to screen macro-molecular pollutants via steric exclusion mechanism, but unable to deal with small molecules, e.g. dyes and antibiotics. Herein, we develop a novel PVDF piezocatalytic membrane with manipulated spherical and polar structure directly through TIPS (thermally induced phase separation) without additional mechanical or electrical poling, showing excellent self-catalytic decontamination and self-cleaning fouling resistance without external addition of oxidants. By using a polar, environmentally benign compound caprolactone as a diluent, carbon nanotube as a polar inducer, a PVDF/SWCNTs (Single Walled Carbon Nanotubes) piezoelectric membrane with a high β-phase content of 93% was prepared. The quench temperature, quench bath composition, doping content of SWCNTs have a substantial manipulation effect on β-phase generation, piezoelectric property and catalytic performance. The optimal membrane achieved a competitive catalytic efficiency of 96.8% within 40 min, with a kinetic rate constant of 0.095 min −1 , a piezoelectric coefficient d 33 of 41.6 pC N −1 , and a flux recovery rate of 89.6%. This study demonstrates that the PVDF piezoelectric membrane with spherical and polar structure via TIPS provides an effective active separation pathway for water remediation in contrast to traditional micro-or ultra-filtration membranes.