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首页> 外文期刊>Polymer: The International Journal for the Science and Technology of Polymers >Liquid-liquid phase separation in a ternary system of segmented polyetherurethane/dimethylformamide/water:effect of hard segment content
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Liquid-liquid phase separation in a ternary system of segmented polyetherurethane/dimethylformamide/water:effect of hard segment content

机译：聚醚氨基甲酸酯/二甲基甲酰胺/水三元体系三元体系中的液-液相分离：硬链段含量的影响

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摘要

A series of segmented polyurethanes (SPUs) using poly(tetramethylene oxide) (PTMO),4,4'-methylenebis (phenyl isocyanate) (MDI), and ethylene glycol (EG) with different molar ratios of MDI and PTMO were prepared to study the effects of teh hard segment content in SPU on liquid-liquid phase separation in the SPU/dimethylformamide(DMF)/water system.The could points were obtained by a titration method and the phase diagrams were calculated based on the Flory-Huggins thermodynamics.The DMF-SPU interaction parameter,X_(23) was determined by the intrinsic viscosity measurement.The water -SPU interaction parameter,X_(13) was measured by an equilibrium swelling experiment.As teh hard segment fraction in SPU increased,the values of X_(23) increased slightly and those of X_(13) decreased significantly.The amount of water to achieve liquid demixing increased systematically with the hard degment content.The X_(13) values in the practical concentration range were estimated by comparison of the calculated phase diagrams with the experimental cloud points.Liquid-liquid phase separation was coupled with liquid-solid phase separation (crystallization) when the SPU had high concentration of the hard segment. These coupled phenomena in combination with the phase segregatioin in SPU arising from the incompatibility between the hard and soft segments may be utilized to produce a variety of the morphologies of polyurethane membranes prepared by immersion precipitation.
机译：制备了一系列的聚对苯二甲酸乙二醇酯（PTPU），4,4'-亚甲基双（苯基异氰酸酯）（MDI）和乙二醇（EG），分别使用不同摩尔比的MDI和PTMO的分段聚氨酯（SPU）进行研究SPU /二甲基甲酰胺（DMF）/水系统中固相含量对液-液相分离的影响。通过滴定法获得可能的点，并基于Flory-Huggins热力学计算相图。通过特性粘度测量确定DMF-SPU相互作用参数X_（23）。通过平衡溶胀实验测量水-SPU相互作用参数X_（13）。随着SPU中硬链段分数的增加， X_（23）略有增加，X_（13）的含量显着下降。实现液体分解的水量随硬质含量的增加而系统地增加。通过计算比较得出实际浓度范围内的X_（13）值当SPU的硬链段浓度高时，液-液相分离与液-固相分离（结晶）结合。由硬链段和软链段之间的不相容性引起的这些结合现象与SPU中的相偏析相结合，可用于生产通过浸没沉淀制备的各种聚氨酯膜形态。

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