渗透汽化芳烃/烷烃分离膜材料

芳烃/烷烃混合物的分离在石油化工及环保领域都具有重大意义.与传统的萃取精馏等技术相比,渗透汽化膜技术以其清洁、节能和高效的优点,应用于芳烃/烷烃混合物的分离并受到重视.本文综述了渗透汽化芳烃/烷烃分离膜的研究进展,概述了渗透汽化技术的基本原理和应用,重点介绍了用于渗透汽化芳烃/烷烃分离的聚酰亚胺、聚氨酯等高分子膜材料的结构特点和分离性能.总结了膜材料的接枝、共聚和共混,添加传质促进剂的改性方法.分析了渗透汽化芳烃,烷烃分离膜材料的研究思路,在此基础上对渗透汽化芳烃/烷烃分离膜材料的研究方向和发展前景进行了展望.     

环境响应型微孔膜

对微孔膜材料进行表面改性后可得到具有环境响应性的"化学阀",其渗透、分离性能可随外界环境的变化而相应改变.本文较详细地介绍了这类功能膜的制备方法,重点描述了在pH、温度、光等的作用下膜的刺激响应功能以及对这种功能的模型解释.     

渗透汽化优先透醇分离膜

20世纪70年代的能源危机促使了人们对可再生能源-发酵法制备乙醇与节能分离工艺的探求。渗透汽化膜分离技术作为一种新兴的膜分离技术,具有分离效率高、低能耗、易于和发酵装置耦合、易于与其它分离方法联用等显著优点,特别适用于乙醇/水等恒沸混合物体系的分离。本文简要介绍了渗透汽化优先透醇膜的研究背景,总结并分析了用于指导膜材料选择的理论,详细介绍了用于制备优先透醇膜的含硅聚合物、含氟聚合物、有机/无机复合膜材料以及其他聚合物等膜材料的的结构特点、改性方法及膜材料分子结构与渗透汽化性能间的关系,并对不同膜材料对乙醇/水的渗透汽化分离性能进行了总结比较,在此基础上总结了目前渗透汽化乙醇/水分离膜存在的问题,并对其未来的研究方向和发展前景进行了展望。     

两性离子在高分子膜表面功能化改性中的研究进展

两性离子的合成工艺简单,官能团适用性强,且在水溶液中具有较强的水合能力与抑制蛋白质吸附性,因此两性离子在高分子膜表面的功能化改性中显示出很大的优势。将两性离子接枝于高分子膜表面可得到抗污染性强,血液相容性好,环境刺激响应性迅速的功能化膜。两性离子功能化改性高分子膜不仅能广泛应用于水处理和医务治疗中的人工器官材料、血浆分离等领域,在生物医药工业中的蛋白质浓缩、净化与分离等方面同样显示出巨大的应用空间。     

渗透汽化分离芳烃/烷烃混合体系的研究进展*

本文对近年来应用于分离芳香烃/ 烷烃混合体系的渗透汽化(简称PV ) 膜材料, 特别是高分子材料进行了较为系统的综述, 并简要概述了渗透汽化膜分离特点、机制以及影响渗透汽化分离过程的主要因素。     

高分子分离膜表面的糖基化

高分子分离膜表面的糖基化立足于仿生膜表面的构建，通过多种方法在膜材料表面引入糖基，将膜的分离性能与糖的生物功能相结合，形成具有复合功能的统一体．本文分别从糖基化方法和糖基化膜材料的应用两方面对高分子分离膜表面糖基化工程的研究现状和进展进行了总结．     

智能高分子表面的设计及其在生物医学中的应用

一般高分子材料表面对外界刺激反应性较弱,但利用一些化学或物理方法可提高其响应性,使其智能化。本文介绍了近年来智能高分子表面的几种设计思路、响应机理及其在生物医用材料方面的应用,并且提出了今后的发展趋势。     

低温氧等离子体改性海藻酸钠膜分离乙醇—水溶液

研究了氧等离子体对海藻酸钠膜的表面改性，并将该膜用于渗透汽化分离乙醇－水溶液。通过红外光谱、表面电阻、接触角等手段测试，表明在海藻酸钠膜表面增加了羟基、羧基及羰基，因而更加亲水。当分别用未处理的原始膜，氧等离子体处理膜处理表面对着原料液，以及处理表面对着减压侧用于渗透汽化法分离乙醇－水混和物时，性能明显不同。其结果是：上表面处理后，渗透通量明显增加，分离系数也较未处理略高；下表面处理后，渗透速度下     

高分子表面环境响应的应用

高分子表面具有环境响应性，利用此特性可设计新型表面功能材料。本文叙述了高分子表面环境响应性应用的进展。     

壳聚糖膜结构与乙醇／水混合液的渗透汽化性能

用渗透汽化膜分离混合液体,纤维素、赛璐玢等作醇/水分离膜有较高的渗透通量,但分离系数低.甲壳素是广泛存在于自然界的一类天然高分子.前文报道了用甲壳素脱乙酰基的产物壳聚糖(CS)作醇/水渗透汽化(PV)分离膜,在一定的原料液浓度下具有较好的选择渗透性.本文讨论CS膜结构对乙醇/水混合液PV性能的影响,并探讨了提高选择性的途径.     

表面改性氢氧化镁阻燃聚丙烯的研究进展

聚丙烯是综合性能良好的五大通用塑料之一,但是其易燃的特点限制了其在很多领域的应用。氢氧化镁(MH)作为一种环境友好型的无机阻燃剂,常被用于阻燃聚丙烯,但是未经改性的MH极性强,易团聚,与基体的相容性差,难以在聚合物基体中均匀分散,在导致阻燃效率低的同时,对复合材料的力学性能也有很大的负面影响,为提高MH在聚合物基体中的界面相容性,往往需要对MH进行表面改性。本文总结了近几年来以表面化学改性、表面接枝改性、微胶囊化改性三种方法改性的MH阻燃聚丙烯的研究进展,并对其下一步的研究方向进行了展望。     

直接氟化表面改性技术研究进展

直接氟化是直接用氟气作为氟化试剂对高聚物进行表面改性的新方法。其在聚合表面形成纳米级的氟化层,使得聚合物在其本体力学性能不受影响的情况下阻隔性、表面可粘接性等性能得到明显提高,并得到实际应用。同时直接氟化还可用于对碳纳米管、石墨以及分离膜等进行表面氟化改性,可提高其在溶剂中的分散性,电性能和选择分离性。该方法具备成本低,不需要催化剂,改性效果显著和工艺简单等优点。本文主要对直接氟化改性技术的发展、应用、直接氟化基本原理以及相关研究进展进行了综述。     

Relationship between Energy Characteristics of Surface of Polymeric Membranes and Their Transport Properties

Molecular theory of wetting was used to calculate the specific free surface energy of membranes based on amorphous polymers of varied chemical structure from experimental wetting angles obtained for test fluids. A relationship was found between the dispersion component of the surface energy of a membrane, its gas permeability, and free volume of the polymer. This makes it possible to employ the wetting method to prognosticate the transport properties of polymeric membranes. In wetting of membranes with aqueous solutions of alcohols, the concentration of an alcohol corresponding to the onset of its sorption into the membrane was determined. The correlation of the value obtained with the alcohol concentration that corresponds to the onset of sorption and is determined independently by the gravimetric method enables use of wetting angles for optimizing the conditions of experiments on nanofiltration and pervaporation.     

Enhanced desulfurization performance and swelling resistance of asymmetric hydrophilic pervaporation membrane prepared through surface segregation technique

The severe swelling behavior of most hydrophobic membranes has always been an obstinate problem when separating organic mixtures by pervaporation. In some cases, hydrophilic membranes may be an appropriate alternative. In this study, amphiphilic copolymer Pluronic F127 was employed as a surface modifier to fabricate polyethersulfone (PES) asymmetric pervaporation membranes via surface segregation. The scanning electron microscopy (SEM) photographs showed an asymmetric structure of PES/Pluronic F127 membranes. The Fourier transform-infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements confirmed the hydrophilic modification of the membrane surface. Based on the distinct difference of solubility in water between thiophene and n-octane, the prepared membranes were utilized to remove thiophene from n-octane by pervaporation. The effect of Pluronic F127 content on the pervaporation performance was evaluated experimentally. It has been found that both the permeation flux and enrichment factor exhibited a peak value of approximately 60 wt% of the Pluronic F127 content. The highest enrichment factor was around 3.50 with a permeation flux of 3.10 kg/(m² h) for 500 mg/L sulfur in the feed at 30 °C. The influence of various operating parameters on the pervaporation performance was extensively investigated.     

Role of additives in the water vapor transport through block co-poly(amide/ether) membranes: effects on surface and bulk polymer properties

In the last years there has been a growing industrial interest in modifying the performance of traditional polymers by using additives, working as modifiers for processing, rheological, transport, bonding, and pigmentation properties. This work was focused on the understanding of the relationships between chemical structure and water vapour transport through a polymer matrix modified by different additives regarding hydrophilicity and molecular structure. A screening of the changes in surface energies and bulk morphology, as a function of the chemical nature and weight percent modifier, allowed estimating the effects on the water vapour transport through polymer membranes. Static and dynamic contact angle measurements explained the difference in surface wettability and affinity to polar species such as water molecules. Modifiers having polar groups improved the surface hydrophilicity, enhancing the breathability of the membranes, while hydrophobic components such as aromatic structures led to a reduction of the water vapour mass uptake onto the membrane surface. On the other hand, thermal analyses showed a tendency of the polymer structure to reduce its own mobility with consequent slowdown of the diffusion through polymer matrix. Modification with large and bulky structures disrupted the polymer packing density, but simultaneously increased the stiffness of the polymer chains, inhibiting the penetrant migration. As a result, balancing the effects due to modifier polarity and bulky structure, it is possible to change the performance of a polymer in terms of transport, going from breathable membranes to barrier films.     

两亲性共聚物的分子设计与合成及其共混膜性能

从分子结构设计出发,采用自由基聚合、醚化、酯化、原子转移自由基聚合(ATRP)、可逆加成断裂链转移自由基聚合(RAFT)等方法合成了一系列具有不同分子结构(包括接枝、嵌段、交替、超支化等)和链形态(包括直链、梳状、哑铃状、链球状等)的两亲性共聚物,并对这些聚合物进行了谱学表征和性能测试.将这些两亲性共聚物与聚合物膜材料(包括聚偏氟乙烯、聚氯乙烯、聚砜、聚醚砜、聚醚砜酮等)进行溶液共混,通过相转化法制备共混膜,在成膜热力学和动力学分析的基础上,对共混膜的结构和性能进行调控.研究发现,两亲性共聚物在成膜过程中自发地向膜表面迁移富集,并进行自组装,在膜表面形成两亲性共聚物包膜,显著改善了聚合物多孔膜的亲水性和抗污染性能.此外,两亲性共聚物中的功能基团还可赋予共混膜某些功能特性,如生物相容性、环境响应性(pH、温度敏感性)、酶活性等.     

高分子表面改性剂的分子设计

简述高分子表面改性剂对聚合物进行表面改性的微观模型，讨论了高分子表面改性剂的分子结构、分子量以及加工工艺条件对表面改性效果的影响，提出了高分子表面改剂的分子设计原则。     

生物多糖进行医用高分子材料表面修饰的研究进展

综述了国内外应用生物多糖进行医用高分子材料表面修饰的研究状况,其中重点介绍了葡聚糖、肝素及类肝素类物质、壳聚糖等多糖在高分子材料表面修饰的研究近况.多糖是自然界中含量最为丰富的生物大分子,几乎存在于所有的生命体中,具有很好的生物相容性,而且某些生物多糖还具有特殊的生物活性,因此用生物多糖进行医用高分子材料的表面修饰受到了国内外研究学者的关注.大量研究表明,经过生物多糖表面修饰的高分子材料可获得良好的生物相容性和某些优良的医学应用性能.     

Polymeric membranes: Surface modification for minimizing (bio)colloidal fouling

This paper presents an overview on recent developments in surface modification of polymer membranes for reduction of their fouling with biocolloids and organic colloids in pressure driven membrane processes. First, colloidal interactions such as London–van der Waals, electrical, hydration, hydrophobic, steric forces and membrane surface properties such as hydrophilicity, charge and surface roughness, which affect membrane fouling, have been discussed and the main goals of the membrane surface modification for fouling reduction have been outlined. Thereafter the recent studies on reduction of (bio)colloidal of polymer membranes using ultraviolet/redox initiated surface grafting, physical coating/adsorption of a protective layer on the membrane surface, chemical reactions or surface modification of polymer membranes with nanoparticles as well as using of advanced atomic force microscopy to characterize (bio)colloidal fouling have been critically summarized.     

医用高分子表面及其血液相容性

本文首先概述了医用高分子表面的表征方法。接着着力讨论材料和血液的相互作用,其中主要阐述目前血液相容性研究所涉及的内容和各种抗凝假设。最后具体介绍了几种常见医用高分子材料的表面特性。