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Role of thermodynamic and kinetic interaction of poly(vinylidene fluoride) with various solvents for tuning phase inversion membranes
Author(s) -
Kurada Krishnasri V.,
De Sirshendu
Publication year - 2018
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24666
Subject(s) - materials science , membrane , polymer , phase inversion , crystallinity , solvent , chemical engineering , polymer chemistry , formamide , porosity , phase (matter) , thermodynamics , composite material , organic chemistry , chemistry , biochemistry , physics , engineering
An extensive study of thermodynamics and kinetics of non‐solvent induced phase separation was carried out for poly(vinylidene fluoride)/solvent/water system for four different solvents. Literature available on semicrystalline polymers was mostly based on experimental cloud points, obtained to a narrow range of polymer concentration (<10 wt%), much less than the working range for membrane preparation (20–25 wt%). Aim of this work was to model the thermodynamic phase diagram using extended Flory–Huggins theory which was used as a tool, along with the kinetic data to obtain tailor‐made membranes with desired morphology and properties. Interaction parameters involving solvent, nonsolvent, and polymer played an important role to tune the porosity of the membrane. Thermodynamic calculation showed solvent N , N ‐dimethyl acetamide resulted in the most porous membrane (permeability 5.4 × 10 −11 m Pa −1 s −1 ) followed by N , N ‐dimethyl formamide (permeability 4.2 × 10 −11 m Pa −1 s −1 ), N ‐methyl pyrrolidone (permeability 3.8 × 10 −11 m Pa −1 s −1 ), and acetone (impermeable to water even at 1380 kPa), which was the densest one. Prepared membranes were characterized in terms of surface morphology, molecular weight cut‐off, tensile strength, pore volume distribution, crystallinity, and surface roughness, which were correlated to inferences based on thermodynamic and kinetic calculations. POLYM. ENG. SCI., 58:1062–1073, 2018. © 2017 Society of Plastics Engineers