摘要
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(T<Ts),由于存在栅栏效应,透过通量较小;高温时(T>Ts),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 used for selective separation of substances with different molecular sizes.According to differential scanning calorimetry （DSC） and Xray diffraction （XRD） analysis,it was found that the TSPU showed segmented structure and separate phase transition temperatures of soft segment phase and hard segment phase （the phase transition temperature of the soft segment phase was defined as the switch temperature,Ts）.Polarizing optical microscope （POM） analysis showed that the soft segments of TSPU had a clear spherulite morphology at low temperatures （〈Ts）.However,when the temperature exceeded Ts,the crystall of soft segments melted gradually and disappeared.The morphological structure of membranes was observed by scanning electron microscope （SEM） and atom force microscope （AFM）,the results indicated that the membrane showed relatively dense surfaces （or skin） and porous cross sections.The porosity of membranes measured by the mass loss of wet membranes after drying revealed that when the temperature increased from Ts-10℃ up to Ts＋10℃,the porosity of membranes increased from 467% to 653%,showing a significant feature of thermal stimulation.When this TSPU membrane was used for separation of substances with different molecular sizes,we found that the ions of Na＋ and Cl-（with small size） could permeate the TSPU membrane at any temperature,and higher temperature resulted in higher penetration rate.Whilst the penetration of glycin （with moderate molecular size） relied on the temperature variation.To be specified,at lower temperatures （T〈Ts）,the glycin permeation flux was very low,but when the temperature exceeded Ts,the permeation flux of glycin increased markedly,showing sensitivity to thermal stimuli.Collagen,due to its large molecular size,could not permeate the TSPU membrane in all temperature range.As a result,substances with different sizes could be selectively separated by the TSPU membrane under temperature controlling.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2010年第3期308-315,共8页
Acta Polymerica Sinica
基金
国家新世纪优秀人才支持计划(项目号NCET-05-0782)资助项目
关键词
温敏聚氨酯
分离膜
温敏特性
选择性分离
胶原蛋白
氨基酸
Thermal sensitive polyurethane Membrane Thermal sensitivity Selective separation Collagen Amino acids
