Influence of Preparation Temperature on the Properties and Performance of Composite PVDF-TiO2 Membranes

Composite PVDF-TiO2 membranes are studied extensively in literature as effective anti-fouling membranes with photocatalytic properties. Yet, a full understanding of how preparation parameters affect the final membrane structure, properties and performance has not been realized. In this study, PVDF-TiO2 membranes (20 wt% TiO2/PVDF) were fabricated via the non-solvent-induced phase separation (NIPS) method with an emphasis on the preparation temperature. Then, a systematic approach was employed to study the evolution of the membrane formation process and membrane properties when the preparation temperature changed, as well as to establish a link between them. Typical asymmetric membranes with a high porosity were obtained, along with a vast improvement in the permeate flux compared to the neat PVDF membranes, but a reduction in mechanical strength was also observed. Interestingly, upon the increase in preparation temperature, a significant transition in membrane morphology was observed, notably the gradual diminution of the finger-like macrovoids. Other membrane properties such as permeability, porosity, thermal and mechanical properties, and compression behavior were also influenced accordingly. Together, the establishment of the ternary phase diagrams, the study of solvent-nonsolvent exchange rate, and the direct microscopic observation of membrane formation during phase separation, helped explain such evolution in membrane properties.

Automated summary

This study investigated the effects of preparation temperature on the formation process and properties of PVDF-TiO2 membranes. An increase in preparation temperature led to changes in membrane morphology, increased porosity, improved permeate flux, but decreased mechanical strength. Factors such as permeability, porosity, thermal and mechanical properties, and compression behavior were all influenced by the preparation temperature.