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通过湿法转相技术制备了温敏聚氨酯(thermal sensitive polyurethane,TSPU)膜,并用于氯化钠、甘氨酸和胶原蛋白等不同尺寸物质的选择性分离.示差扫描量热分析仪(DSC)和X射线衍射(XRD)分析表明,TSPU具有典型的嵌段结构(即软段和硬段),软段和硬段具有各自的结晶相及相态转变温度(将软段的相转变温度定义为开关温度,Ts).热台偏光显微镜观察表明,当温度低于Ts时,TSPU的软段具有较好的结晶形态,且为球晶型;但当温度超过Ts后,软段的结晶逐渐熔融、消失.运用扫描电镜(SEM)和原子力显微镜(AFM)对TSPU膜的形貌结构进行分析,结果表明,TSPU膜的表面(层)相对致密,且具有细小的微孔结构;截面为非对称的多孔结构,这种形态结构对TSPU膜的选择渗透性起决定性作用.通过测定湿膜干燥后的质量损失来计算膜的孔隙率发现,当温度从Ts-10℃升高到Ts+10℃时,膜的孔隙率从46.7%上升到65.3%,表现出明显的温敏特性.将TSPU膜用于氯化钠、甘氨酸和胶原蛋白分离时发现,尺寸较小的物质如钠离子和氯离子在低温下即可透过,且透过通量随温度的升高而增大.而中等尺寸甘氨酸的透过通量则呈现明显的温度依赖性,即低温时(TTs),甘氨酸的透过通量明显增大,显示出了温敏特性.胶原蛋白由于分子尺寸大,即使在开关温度以上,也不能透过TSPU膜.因此,利用TSPU膜的温敏特性,可以实现胶原蛋白、氨基酸、氯化钠等不同尺寸物质的选择性分离.
Thermal-sensitive polyurethane (TSPU) membranes were prepared by wet-phase inversion technique and were used for the selective separation of different size materials such as sodium chloride, glycine and collagen.Differential scanning calorimetry (DSC) and X X-ray diffraction (XRD) analysis shows that TSPU has typical block structure (soft and hard segments), soft segment and hard segment have their own crystalline phase and phase transition temperature (the soft segment phase transition temperature is defined as the switch Temperature, Ts) .The observation of the hot stage polarization microscope shows that the soft segment of TSPU has a good crystal morphology and a spherulite shape at temperatures below Ts, but the soft segment gradually melts when the temperature exceeds Ts, Disappeared.The morphology of TSPU films was analyzed by scanning electron microscope (SEM) and atomic force microscope (AFM). The results showed that the surface (layer) of TSPU films was relatively dense and had a fine microporous structure. The cross section was asymmetric Porous structure, the morphological structure of TSPU film permeability is decisive.Determination of the mass loss after drying the wet film to calculate the membrane porosity found that when the temperature from Ts-10 ℃ to Ts +10 ℃ , The porosity of the membrane increased from 46.7% to 65.3% A clear temperature-sensitive characteristics of the TSPU membrane for sodium chloride, glycine and collagen separation found that smaller size substances such as sodium and chloride ions can be transmitted at low temperatures, and the flux through the temperature (T Ts), glycine flux increased significantly, showing the temperature-sensitive properties of collagen because of its large size, even above the switching temperature can not penetrate the TSPU membrane.Therefore, the use of TSPU membrane temperature-sensitive properties, Can be achieved collagen, amino acids, sodium chloride and other selective separation of substances of different sizes.