The effect of polyethylene glycol on formation kinetics of membrane formation via phase-inversion process

The effect of polyethylene glycol (PEG) on membrane formation kinetics was investigated in polyether-sulfone with cardo/PEG/N, N dimethylacetamide cast solution. The results showed thatThe membrane formation kinetics result was different from a commonly accepted conclusion obtained by strathman et al. that a single linear correlation between square of precipitation front move(L²) and gelation time(t) existed for the whole gelation process. Four different linear correlations between the value of L² and gelation time, t, were identified. Compared to the morphology evolution of the membrane, these four correlations correspond to four consecutive gelation steps. The maximal gelation rate constant occurred the top layer. The natural logarithm value increased linearly with the increase of concentration of PEG. The addition of PEG could work in favor of the enhancement in the demixing of casting solution thermodynamically. The introduction of PEG made the effect of the cast solution viscosity hindrance exceed the effect of thermodynamic enhancement.