聚乙二醇对相转化成膜过程凝胶动力学的影响研究

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

以酚酞基聚芳醚砜/聚乙二醇/N,N-二甲基乙酰胺为铸膜液体系,考察了聚乙二醇对非对称膜成膜过程凝胶动力学的影响。结果表明,成膜过程中凝胶动力学的研究结果得到与Strathman等人不同的结果,凝胶前锋位移的平方与时间不是简单的线性关系,凝胶动力学过程不能简单的用Fick扩散定律来描述。提出将凝胶过程与非对称膜的结构相对应分为4个连续的凝胶过程,凝胶速度曲线由4段具有不同速度常数的线段组成,每一段的速度常数大小和膜横截面上的不同结构相对应。在凝胶过程中,凝胶速度常数最大的是皮层。聚乙二醇浓度增加,在热力学上加速了铸膜液的相分离,铸膜液黏度的自然对数值线性增加,铸膜液黏度对凝胶速度的影响比热力学因素的影响要大。

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（L^2） and gelation time（t） existed for the whole gelation process. Four different linear correlations between the value of L^2 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.