取向聚氨酯／液晶复合膜血液相容性材料的表面形态表征

模仿生物膜的表面结构形态,将有序的、流动的胆甾醇液晶(LC)与基质材料聚氨酯(PU)共混,在不同强度的电场条件下制成取向PU/LC复合膜,作为抗凝血生物材料.表征了不同取向条件下复合膜表面液晶畴取向性、体积、形状及其与电场强度、液晶含量的相关关系.结果表明:复合膜表面呈现出的形态特征是液晶含量、电场强度综合影响的结果;电场可以调控指状液晶畴的体积、分布,通过电场调控可获得具有适宜相分离程度和有序性的复合膜.     

橡胶/液晶复合膜的形态结构与透气性能

以顺丁橡胶（ＰＢ）和具有双重液晶相的液晶化合物双－４（４＇－乙氧基苯甲酰氧基）苯甲酸－缩乙二醇酯（ＤＥＢＥＢ）制成了不同液晶含量的高分子复合膜,并研究了其气体透过性能。复合膜具有两个明显的特征：１）室温下,所有复合膜的透气系数均大于纯ＰＢ膜,其中ＰＢ／ＤＢＢＥＢ（质量比为９０／１０）的复合膜具有比纯ＰＢ膜大６倍的透过系数（ＰＯ２＝５４．７、ＰＳ２＝１７和ＰＣＯ２＝４３２Ｂａｒｒｅｒ,１Ｂａｒｒｅｒ     

PPC/PCU液晶复合膜的制备及其性能研究

采用溶液浇铸法和熔融法制备丙酰氧丙基纤维素/聚碳酸酯聚氨酯(PPC/ PCU)液晶复合膜.通过SEM、AFM、表面能量参数测定、溶血和动态凝血试验,研究了复合膜的表面形貌特征和血液相容性,考察了复合膜的制备方法和液晶含量对其性能的影响.结果表明,复合膜表面呈现微相分离结构,PPC液晶能明显改善PCU材料的血液相容性,改善的程度与复合膜中液晶的含量相关.由不同方法制备的复合膜,其表面的形态结构和表面能量参数不一样,采用溶液浇铸法制备的复合膜,其接触玻璃板的表面可见明显的海岛状微相分离结构,复合膜的血液相容性最好.     

聚丁二烯／液晶复合膜的结构形态研究

在聚丁二烯／液晶复合膜中，液晶的分布方式与液晶含量以及环境温度有关。当液晶含量超过３０％时，５０℃以下液晶呈连续的球状体，５０℃以上液晶相呈连续的流动态。由于聚丁二烯分子与液晶分子的相互分散和交联的影响，使复合膜中的液晶相ＴＫＮ比纯液晶的ＴＫＮ降低了约３０℃。当具有一定压力的气体通过复合膜后，复合膜的结构形态也发生了一定的变化。本研究利用ＤＳＣ、ＳＥＭ、ＴＥＭ及ＯＰＭ对复合膜的结构形态进行了表征，     

聚氨酯／液晶复合膜的抗凝血性能研究

以聚醚型聚氨酯为基质材料，分别与向列型和胆甾型液晶化合物在适当溶剂中溶解共混后，利用溶剂发法在聚四氟乙烯板上浇铸成膜。研究了了复合膜中的液晶含量和成膜条件对复合膜表面结构形态的影响，同时详细研究了液晶含量对复合膜动态凝血性能、血小板粘附性能以及溶血性能的影响。研究结果表明，只有当复合膜中的液晶质量份数超过３０％时，复合膜才表现出良好的抗凝血性能，且液晶含量的增加而复合膜的抗凝血性能有明显的改善，尤其是复合膜表面吸附的血小板数量随液晶含量的增加而明显减少。     

液晶／聚合物复合膜的性能及其富氧效果

随着高分子材料科学的飞跃发展,人们期望着Po_2、αo_2/N_2值均优良的膜材料出现。液晶/聚合物复台膜首先由日本科学家KAJIYAMA使用苄叉类液晶与PVC(聚氯乙烯)共混后制成二元复合膜,Po_2达5.75×10~(-10)cm~3·cm·cm~2·sec~1·cmHg~1、αo_2/N_2达到2.95。清华大学化学系王良御、杨诚用苯基环乙烷类液晶与PVC共混制成的复合膜在北京氧气厂试验时Po_2达到134.7×10~(10)cm~3·cm·cm~2·sec~1·cmHg~1,α达到4.45,普通空气经过分离后可以得到含O_2 42％的富O_2空气。实际分离系数α’o_2/N_2=2.27。通过对不同含O_2量的原料气的渗透试验证明,复合膜的α’对浓度不同的原料气有不同的值。     

液晶性能对聚氨酯／液晶复合膜抗凝血性能的影响

合成了3种亲水性胆甾醇液晶化合物,HO-[CH2CH2]-nO-C∧‖O-O-Chol（n=2,3,4）,用元素分析法、红外光谱、差热分析以及偏光显微镜观察对其结构进行了表征,利用聚氨酯与上述液晶化合物制备复合膜,研究了液晶性能对聚合物/液晶复合膜抗凝血性能的影响,结果表明,胆甾醇液晶化合物有利于改善聚合物材料的抗凝血性能。     

基材与液晶种类对液晶复合膜血液相容性的影响

从仿生学的角度设计和制备结构及组成与生物膜及血管内壁相似的聚合物/液晶复合膜,作为新一类抗凝血生物材料,并通过血液相容性试验考察复合材料的抗凝血性能.结果显示:不同基材及液晶种类的聚合物/液晶复合膜,其溶血率值均小于5%,符合生物材料溶血试验的要求;复合膜的动态凝血性能取决于基材与液晶两者之间的兼容性及配比,动态凝血性能较佳的复合膜表面粘附的血小板大多呈单个粘附状态,数量较少,且基本无变形,呈现出良好的血液相容性.     

摩擦取向膜表面液晶薄层厚度的研究

基于液晶具有光学单轴晶体的性质 ,结合阿贝折射仪测出了方位折射率 ,利用反射椭偏消光法测量原理解决了在多层介质膜上液晶吸附层厚度测量问题。利用这种方法测量了经过摩擦取向处理的高分子取向膜表面的液晶薄层厚度。实验发现 ,经过不同摩擦强度处理后的取向膜吸附液晶薄层的厚度为 5 4nm± 3nm。     

Polymer dispersed liquid crystal fiber optic electric field probe

Polymer dispersed liquid crystal inserted between two multimode optical fiber end faces forms the basis of an electric field probe. This probe has an active volume of about 0.001 mm³ and approximates a point measurement. The linear relation between detector output and electric field in the 600 V/cm to 800 V/cm range is adequate for most electric power distribution systems. As the contrast ratio of this transducer is large, it can also be used as a safety on-off detector for high-voltage equipment     

电场强化组装聚离子复合物膜研究

采用水解改性PAN超滤膜作为基膜.通过动态电场强化技术复合聚乙烯亚胺(PEI)制备聚电解质渗透汽化复合膜,考察了不同电压对聚离子复合膜的渗透汽化性能的影响.实验测定了复合膜对不同醇/水体系的分离性能,发现在仅复合一层PEI时,电场强化LBL组装膜(5 V电压作用)对质量分数为95%的异丁醇/水体系的分离因子可达485,渗透通量为1521g/(m2·h)(60℃).     

PU/PVC复合膜的制备及应用

采用湿法相转化法制备了PU/PVC/SiO2复合膜,并用膜性能测试仪、扫描电子显微镜测试了膜的性能与结构.结果显示:SiO2的加入,可改善PU杂化膜的微孔结构并优化膜的性能,在该体系中加入PVC和PU共混,可以提高成膜速度及微孔结构,水通量和截留率得到了明显的提高.将制得的超滤膜用于处理麻杆蒸煮废液取得了较好的效果,与PU复合膜的对卵清蛋白的截留测试结果是一致的.     

On the shape of a rotating liquid drop in an electric field

Summary The axisymmetric relative equilibrium shape of a finite dielectric liquid mass held together by surface tension and rotating uniformly in a uniform axial electric field is determined by expressing the slope of its tangent in terms of confluent hypergeometric functions and following a numerical integration.

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Zusammenfassung Die axialsymmetrische, relative Gleichgewichtsfigur einer endlichen, dielektrischen, durch die Oberflächenspannung zusammengehaltenen Flüssigkeitsmasse, welche gleichförmig in einem axialen elektrischen Feld konstanter Feldstärke rotiert, wird untersucht. Die Steigung der Tangente wird mittels konfluenter hypergeometrischer Funktionen ausgedrückt, und die Gestalt des Flüssigkeitstropfens durch numerische Integration bestimmt.

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With 1 Figure

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Presented at the Fifth United States National Congress of Applied Mechanics, University of Minnesota, Minneapolis, Minnesota, USA, June 1966; an abstract appears on page 764 of the proceedings.     

Collagen/hydroxyapatite composite obtained by electric field orientation

The purpose of this study was to obtain and characterize the oriented collagen/hydroxyapatite (COLL/HA) composite materials, using different kind of electric field. The orientation process takes place due to the dipolar collagen structure. The collagen molecules are electrically charged and can become oriented if an electric field is applied. The composites were obtained by the co-precipitation method starting from collagen gel and hydroxyapatite precursor. The mineralized collagen gel was introduced in an electric field for 1 h, frozen and lyophilized. In order to study the orientation process parameters, two types of electric fields were tested: pulsatory and superposed (both direct and pulsatory). The obtained materials were characterized by XRD, FTIR and SEM. Best results in what it concerns the oriented character of the microstructures, as resulted from SEM images, were obtained for a pulsatory field of 0.93 V/cm, the presence of the direct electric field component decreasing the orientation degree. The average orientation degree, calculated at the magnification of 1000× was about 95%.     

稳恒电场对小晶面晶体生长的影响

本文选用NH4Cl和H2O过饱和二元溶体为研究对象,研究其在稳恒电场作用下溶体中游离晶的重熔规律及晶体生长规律.利用显微镜感光器件(CCD)及智能通讯测温仪表,对实验过程进行实时照片拍摄和实时温度记录.结果表明:电场的Joule Heat效应为决定性因素,使得NH4Cl溶体温度场显著变化,导致糊状区的游离晶重熔明显;N...     

Effects of substrate and orientational property of liquid crystal domains on the blood compatibility of polymer/liquid crystal composite membranes

A series of polymer/cholesteryl liquid crystal (LC) composite membranes were prepared. Polyurethane and polyvinyl chloride, as a substrate, were blended with cholesteryl tetraethylene glycol carbonate to form composite membranes in an electric field under normal conditions. The blood compatibility of composite materials was identified by the dynamic blood-clotting test, haemolysis ratio measurement, platelet adhesion and SEM observation. The results showed that the content of LC, the ordered extent of LC domains embedded in composite materials and the type of substrate have greater effects on the blood compatibility of polymer/LC composite materials. When the LC domains were properly oriented, polymer/LC composite membranes had an excellent haemocompatibility, fewer platelets were adhered and spread and showed little distortion on the surface of materials.     

Unidirectionally oriented hydroxyapatite/collagen composite fabricated by using a high magnetic field

A unidirectionally oriented hydroxyapatite (HAp)/collagen composite was prepared by using a high magnetic field. In the present study, a calcium-containing collagen solution was mixed with a phosphate-containing solution and kept at a temperature of 37 °C. During this process, the heat-induced self-assembling of collagen molecules and precipitation of HAp crystals took place simultaneously. Both collagen fibrils and HAp crystals have magnetic susceptibility anisotropy, which makes it possible for them to be oriented by using a high magnetic field. In order to prepare a unidirectionally oriented structure, samples were rotated when the high magnetic field was imposed perpendicularly to the rotation axis. The results indicated that collagen fibrils have been unidirectionally oriented with weakly crystallized HAp nanocrystals closely attached along the surfaces of the collagen fibrils. A biocomposite with similar structural and composition to natural bones has been prepared.     

Preparation of unsaturated polyester/graphite nanosheet conducting composite under electric field

Unsaturated polyester resin/graphite nanosheet composites were prepared using in situ polymerization under AC electric field which was applied during composite curing to induce orientation of graphite nanosheets. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques have been applied to demonstrate the orientation of graphite nanosheets and results showed that graphite nanosheets were oriented with their flakes parallel to the electric field. As a result, the percolation threshold was decreased to 0.25 wt% due to the orientation of the graphite naosheets.