Effect of Additives (PEG400 and LiCl) on the Structure and Morphology of poly vinylidene fluoride (PVDF) Membranes

Asymmetric poly vinylidene fluoride (PVDF) membranes cast with commercial-grade Sigma-Aldrich polymer pellets and solvent N-dimethyl formamide (DMF) system, the effects of concentration of various additives (polyethylene glycol, lithium chloride) on the membrane morphology were investigated. The membrane morphology was examined with scanning electron microscopy. The results showed that the additive causes large and deep pores in the structure of membrane and greater amount of additive causes the pore depth in the structure of membrane and the more viscosity of the polymer solution, the structure of membrane is more finger-like. The addition of PEG has been reported to favor pore formation in the fabrication of PVDF membranes and enhance phase separation of casting solution and addition of LiCl into the PVDF polymer dope resulted in enhancement of porosity and membrane is more finger-like