微乳液聚合耦合共混法构建聚偏氟乙烯共混杂化膜

以苯乙烯和甲基丙烯酸甲酯混合物作为油相, 采用反相微乳液法制备了AgCl纳米粒子; 通过微乳液原位聚合油相单体得到包含AgCl纳米粒子的聚合乳液; 将聚合乳液与聚偏氟乙烯(PVDF)通过共混法构建了包含AgCl纳米粒子的PVDF共混杂化膜. 紫外-可见光谱、 透射电子显微镜(TEM)及扫描电子显微镜(SEM)等表征结果和超滤实验结果表明, 聚合乳液加入的同时引入了亲水性聚合物和表面亲水的AgCl纳米粒子, 不仅改善了PVDF共混杂化膜的孔隙率和平均孔径, 还显著增强了PVDF共混杂化膜的极性和亲水性, 最终提升了膜的水通量和抗污染性能; 过量聚合乳液加入后不能与PVDF材料均匀共混, 而且AgCl纳米粒子也会在膜中形成团聚物堵塞膜孔隙, 从而削弱了膜的水通量和抗污染性能.     

材料润湿性调控及其应用于油/水混合物分离的研究进展

油水混合物(包括油水分层相及其乳液)广泛存在于油井采出液、工业循环水及污染海水中,而目前依然缺乏有效的方法能够实现其高效分离,而通过构筑具有三维网络结构的油水润湿界面为以上问题解决提供了新思路.本文综述了利用特殊润湿性分离油/水混合物的材料的研究进展;针对不同的特殊润湿性,不同的油/水混合物等对这些分离材料进行了总结与评述;提出了目前特殊润湿性材料存在的不足之处,并对未来研究方向进行展望.     

纳米粒子稳定乳液及其在纳米结构合成中的应用*

本文在介绍常规乳状液、微乳液和固体稳定乳液的基础上,着重综述了纳米粒子稳定乳液的特点及其在纳米结构合成中的应用进展,并对目前该研究领域亟待解决的问题进行了分析。纳米粒子稳定乳液具有独特的油、水、固三相环境和水油、水固、油固三个相界面,分散相液滴尺寸可以在微米、亚微米乃至纳米尺度调节,因而可以作为合成组成、结构和性能极为丰富多样的纳米结构的介质。纳米粒子对乳液稳定作用的机理,以及纳米粒子稳定乳液中化学反应的特殊规律还有待深入研究。本文在介绍固体稳定乳液的基础上,着重综述了纳米粒子稳定乳液的特点及其在纳米结构合成中的应用进展,并对目前该研究领域亟待解决的问题进行了分析。纳米粒子稳定乳液具有独特的油、水、固三相环境和水油、水固、油固三个相界面,分散相液滴尺寸可以在微米、亚微米乃至纳米尺度调节,因而可以作为合成组成、结构和性能极为丰富多样的纳米结构的介质。纳米粒子对乳液稳定作用的机理,以及纳米粒子稳定乳液中化学反应的特殊规律还有待深入研究。     

催化剂对乳液模板法制备碳材料形貌的影响

以液体石蜡为油相,间苯二酚和甲醛的水溶液为水相,吐温80和司班80为乳化剂,获得油/水(O/W)型乳状液.将该乳状液聚合、碳化去除模板后制得了碳材料,研究了不同催化剂对所得碳材料形貌的影响.结果表明:选择NaOH为催化剂时,制得的碳材料是一种具有孔壁和孔洞的多孔碳泡沫,典型样品的孔径约为1-2μm;当氨水为催化剂时,所得碳材料是由微球或者相互缠绕的蠕虫状粒子组成的块体材料,这些微球或粒子的直径主要集中在1-2μm,与NaOH为催化剂时所得碳泡沫的孔径尺寸相当.研究发现,氨水的加入使得乳液体系发生了相转化,由原来的O/W型乳液逐渐转变为W/O型高内相乳液.从分子间氢键出发,应用内聚能理论探讨了催化剂导致的乳液相变以及不同形貌碳材料的形成过程.     

反相微乳液中AgCl纳米粒子的可控合成与AgCl/GMA-MMA-AMPS共聚物有机-无机杂化膜的研究

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为表面活性剂,在甲基丙烯酸缩水甘油酯(GMA)和甲基丙烯酸甲酯(MMA)混合物为油相的反相微乳液体系中合成了AgCl纳米粒子,然后通过微乳液聚合制备了AgCl/GMA-MMA-AMPS共聚物有机-无机杂化膜,并用于苯/环己烷混合物的渗透气化分离.利用紫外-可见光谱及透射电子显...     

十二烷基硫酸钠中相微乳液的液晶结构

微乳液是指油、水、表面活性剂、助表面活性剂形成的各向同性的、光学透明或半透明的热力学稳定体系．中相微乳液是指富表面活性剂相与过剩水相、过剩油相形成的三相体系．中相微乳液既可增溶水,又可增溶油,且与过剩水相、油相超低的界面张力,因而在强化采油中引起人们...     

油水分离用天然材料表面化学研究进展

油水乳液和油水混合物的分离对解决工业含油废水以及原油泄漏造成的污染问题具有重要的意义。近年来应用于油水分离的超润湿材料引起了广泛的关注,并展现出良好的应用前景。本文综述了近年来利用超润湿性低成本、环保的天然材料通过过滤和吸附技术分离油水乳液和混合物的研究进展。对于每一种天然材料,如沙粒、木材、椰子壳等,介绍了代表性的研究工作,阐述了其制备过程、润湿特性以及对油水混合物或者油水乳液的分离效果,并讨论了利用超亲水/水下超疏油、超疏水/超亲油两种类型的材料分离不混溶的油水混合物、"水包油"型乳液和"油包水"型乳液等三类油水混合物的物理化学机理。最后,对该领域的挑战和未来的发展方向进行了展望。     

熔融纺丝-拉伸法制备PVDF中空纤维膜及其油-水分离性能

以聚偏氟乙烯(PVDF)为成膜聚合物, 聚全氟乙丙烯(FEP)为添加剂, 聚乙二醇(PEG)和氯化钙(CaCl₂)为复合成孔剂, 采用熔融纺丝-拉伸法制备了PVDF中空纤维膜. 在制膜过程中未使用其它溶剂和稀释剂, 实现了制膜过程的相对绿色化. 分析和讨论了拉伸比对PVDF中空纤维膜结构与性能的影响, 测试了纤维膜的孔径分布、 力学性能和油-水分离性能等. 结果表明, 进行拉伸后处理的膜的孔径分布较窄, 在油包水乳液分离测试中, 分离效率均在97%以上, 表现出良好的油-水分离效果.     

离子液体微乳液合成纳米AgCl及AgCl/poly(MMA-co-St)杂化膜性能调控

在以离子液体氯化-1-十二烷基甲基咪唑(C12mimCl)为表面活性剂,甲基丙烯酸甲酯(MMA)与苯乙烯(St)混合物为油相介质的反相微乳液中合成AgCl纳米粒子,进而采用微乳液原位聚合法制备AgCl/poly(MMA-co-St)杂化膜。通过紫外可见光谱和透射电镜分析了微乳液组成(油相介质组成和增容水量ω)对纳米AgCl粒子形貌的影响。结合扫描电镜和苯、环已烷的溶胀实验探讨了微乳液组成对杂化膜性能的调控作用。结果发现,微乳液油相介质中St/MMA体积比增大有利于在微乳液和杂化膜中获得更多纳米AgCl粒子,增加了杂化膜的苯平衡溶胀吸附量(A∞,b)与苯/环已烷的平衡溶胀吸附选择性(αs,b/c)。在St/MMA体积比为1∶3时杂化膜的A∞,b和αs,b/c分别达到330 mg·g-1和19.21;但过多苯乙烯加入油相介质,其苯环中π键会破坏水核中AgCl粒子的稳定性而引起粒子团聚,从而降低了杂化膜的A∞,b和αs,b/c。反相微乳液中合成的纳米AgCl粒子量随ω增大而增多、粒径增大,杂化膜的A∞,b和αs,b/c随ω的增加而增大。但过高的ω导致微乳液中出现AgCl大粒子,从而引起杂化膜的A∞,b和αs,b/c下降。     

单宁酸/两性离子改性油-水分离膜的制备及性能

以不锈钢网为基材, 利用单宁酸对不锈钢网进行表面预处理并功能化接枝两性离子基团, 制备了新型亲水和水下超疏油的单宁酸/两性离子改性油-水分离膜(TA-ZW-SSM). 利用X射线光电子能谱仪(XPS)、 扫描电子显微镜(SEM)及接触角测量仪等表征了其化学结构、 形态和润湿性. 研究结果表明, 两性离子基团通过化学键接枝在单宁酸预处理的不锈钢网表面. 油-水分离实验结果表明, 对于不同类型的油-水混合物, 本文制备的超亲水和水下超疏油特性的TA-ZW-SSM可实现重力驱动的高效油-水分离, 并具有较好的化学稳定性及再循环性.     

Superhydrophobic and superoleophilic polyethylene aerogel coated natural rubber latex foam for oil-water separation application

The oil-water separation has made an attention due to over-increased production of oily water from the industrial process and everyday routine of humans. The current work reports on preparation and characterization of High-Density Polyethylene (HDPE) aerogel coated Natural Rubber Latex foam (NRLF) with superhydrophobic and superoleophilic character, good sorption capacity for oil-water separation application and were investigated. The HDPE aerogel and the coated NRLF material was prepared by a cooling process from a solution of HDPE in xylene solvent (HDPE sole, which resulted into thermally induced phase separation of the Polyethylene molecular network). The HDPE aerogel coated NRLF displayed a porous surface morphology with particle-like structural features. The HDPE aerogel coated NRLF showed superhydrophobicity with static water contact angle >150°. The effect and recyclability of the HDPE aerogel coated NRLF for oil-water separation was investigated using different model oil solvents to explore their repeatable application in oil spill clean-up process. Modified NRLF shows an excellent mechanical property (compressibility). The average modulus and average stiffness of the modified NRLF increased with the increase of the concentration of HDPE sol. The modified superhydrophobic sponge has good durability under acid and base conditions.     

Thermodynamic and shape memory properties of TPI/HDPE hybrid shape memory polymer

The traditional processing technology of shape memory polymer composites is complex and the cost of high performance filler is high. Therefore, low-cost high density polyethylene (HDPE) was introduced into trans-1,4-polyisoprene (TPI) matrix as reinforcing phase, and a novel shape memory polymer was prepared by mechanical melt blending, which fully exerted the excellent properties of plastic and rubber. Because of the difference in molecular chain distribution between different blend ratios of TPI/HDPE hybrid SMPCs specimens, the change of the blend ratio of the two components affects the thermodynamic and shape memory properties of the SMPCs. A series experimental results show that the TPI/HDPE hybrid SMPCs with the blend ratio of 80/20 has excellent thermodynamic and shape memory properties. And we believe that the relevant conclusions of this study can provide valuable design reference for the development of high-performance TPI SMPCs.     

Shape memory behavior of carbon nanotube‐reinforced trans‐1,4‐polyisoprene and low‐density polyethylene composites

Shape memory composites of trans‐1,4‐polyisoprene (TPI) and low‐density polyethylene (LDPE) with easily achievable transition temperatures were prepared by a simple physical blending method. Carbon nanotubes (CNTs) were introduced to improve the mechanical properties of the TPI/LDPE composites. The mechanical, cure, thermal, and shape memory properties of the TPI/LDPE/CNTs composites were investigated in this study. In these composites, the cross‐linked network generated in both the TPI and LDPE portions acted as a fixed domain, while the crystalline regions of the TPI and LDPE portions acted as a domain of reversible shape memory behavior. We found that CNTs acted as not only reinforced fillers but also nucleation agents, which improved the crystalline degree of the TPI and LDPE portions of the composites. Compared with the properties at the other CNT doses, the mechanical properties of the TPI/LDPE composites when the CNT dose was 1 phr were improved significantly, showing excellent shape memory properties (R_f = 97.85%, R_r = 95.70%).     

三聚氰胺海绵的一步式协同超疏水改性及在油水分离中的应用

通过硝酸(HNO₃)实现两亲性三聚氰胺海绵(MS)的一步式协同超疏水改性, 从而得到了一种具有优异性能的油水分离材料——硝酸改性三聚氰胺海绵(HMMS). 采用傅里叶变换红外光谱(FTIR)、 热重(TG)和扫描电子显微镜(SEM)对HMMS的结构、 形貌和组分进行了表征, 并对其表面润湿性、 机械性能、 吸附性能和油水分离性能等进行了研究. 结果表明, HMMS具有超疏水性, 以及优异的机械性能、 循环使用能力、 选择性吸附能力, 对油水混合物的连续分离效率可达6×10 ⁶ L?m ^-3?h ^-1, 并且可在苛刻的使用环境中保持稳定的物理化学性质.     

Preparation of porous polylactide microspheres by emulsion‐solvent evaporation based on solution induced phase separation

Porous polylactide (PLA) microspheres were fabricated by an emulsion‐solvent evaporation method based on solution induced phase separation. Scanning electron microscopy (SEM) observations confirmed the porous structure of the microspheres with good connectivity. The pore size was in the range of decade micrometers. Besides large cavities as similarly existed on non‐porous microspheres, small pores were found on surfaces of the porous microspheres. The apparent density of the porous microspheres was much smaller than that of non‐porous microspheres. Fabrication conditions such as stirring rate, good solvent/non‐solvent ratio, PLA concentration and dispersant (polyvinyl alcohol, PVA) concentration had an important influence on both the particle size and size distribution and the pore size within the microspheres. A larger pore size was achieved at a slower stirring rate, lower good solvent/non‐solvent ratio or lower PLA concentration due to longer coalescence time. Copyright © 2005 John Wiley & Sons, Ltd.     

Oil-Water Separation Performance of Electrospray Reduced Graphene Oxide Microspheres with a Local Radially Aligned and Porous Structure

Micro-size oil adsorbents are effective for the rapid remediation of special oil spills. Here, N-doped reduced graphene oxide(RGO) microspheres(ca. 150 μm in diameter) with a local radially aligned and porous structure are fabricated by combining electrospray-freeze-drying with thermal treatment for rapid separation of oil-water. Owing to its hydrophobic/oleophilic properties and oriented structure, the N-doped RGO microspheres achieve high capacities and fast adsorption rates for a variety of oils and organic solvents. Furthermore, excellent oil-water separation performance on floating oil/oil-water emulsions and stable cyclic adsorption capacities are obtained for the local radially aligned and porous microsphere. Therefore, N-doped RGO microspheres with the unique porous structure have the potential for the remediation of oily sewage and oil spills.     

Preparation and characterization of chitin whisker-reinforced silk fibroin nanocomposite sponges

For highly porous form such as sponges or scaffolds, the induction of the β-sheet formation of silk fibroin to make the water-stable materials usually results in their high shrinkage leading to a difficulty in controlling shape and size of materials. Thus, the objective of this study was to improve dimensional stability of silk fibroin sponge by incorporating chitin whiskers as nanofiller. Chitin whiskers exhibited the average length and width of 427 and 43 nm, respectively. Nanocomposite sponges at chitin whiskers to silk fibroin weight ratio (C/S ratio) of 0, 1/8, 2/8, or 4/8 were prepared by using a freeze-drying technique. The dispersion of chitin whiskers embedded in the silk fibroin matrix was found to be homogeneous. The presence of chitin whiskers embedded into silk fibroin sponge not only improved its dimensional stability but also enhanced its compression strength. Regardless of the chitin whisker content, SEM micrographs showed that all samples possessed an interconnected pore network with an average pore size of 150 μm. To investigate the feasibility of the nanocomposites for tissue engineering applications, L929 cells were seeded onto their surfaces, the results indicated that silk fibroin sponges both with and without chitin whiskers were cytocompatible. Moreover, when compared to the neat silk fibroin sponge, the incorporation of chitin whiskers into the silk fibroin matrix was found to promote cell spreading.     

Nondestructive technique for the characterization of the pore size distribution of soft porous constructs for tissue engineering

Polymer scaffolds tailored for tissue engineering applications possessing the desired pore structure require reproducible fabrication techniques. Nondestructive, quantitative methods for pore characterization are required to determine the pore size and its distribution. In this study, a promising alternative to traditional pore size characterization techniques is presented. We introduce a quantitative, nondestructive and inexpensive method to determine the pore size distribution of large soft porous solids based on the on the displacement of a liquid, that spreads without limits though a porous medium, by nitrogen. The capillary pressure is measured and related to the pore sizes as well as the pore size distribution of the narrowest bottlenecks of the largest interconnected pores in a porous medium. The measured pore diameters correspond to the narrowest bottleneck of the largest pores connecting the bottom with the top surface of a given porous solid. The applicability and reproducibility of the breakthrough technique is demonstrated on two polyurethane foams, manufactured using the thermally induced phase separation (TIPS) process, with almost identical overall porosity (60-70%) but very different pore morphology. By selecting different quenching temperatures to induce polymer phase separation, the pore structure could be regulated while maintaining the overall porosity. Depending on the quenching temperature, the foams exhibited either longitudinally oriented tubular macropores interconnected with micropores or independent macropores connected to adjacent pores via openings in the pore walls. The pore size and its distribution obtained by the breakthrough test were in excellent agreement to conventional characterization techniques, such as scanning electron microscopy combined with image analysis, BET technique, and mercury intrusion porosimetry. This technique is suitable for the characterization of the micro- and macropore structure of soft porous solids intended for tissue engineering applications. The method is sensitive for the smallest bottlenecks of the largest continuous pores throughout the scaffold that contributes to fluid flow.     

胺功能化配体多孔配位聚合物材料的碳捕捉和封存研究进展

近十年,多孔配位聚合物(porous coordination polymers, PCPs)因其晶体结构中可调节的孔道尺寸、形状以及化学功能化,在小分子的选择性吸附及分离领域受到了极大的关注。基于环境问题的严峻性,胺功能化PCPs材料对煤电厂燃烧废气中CO2优异的选择性吸附性能,使其在该领域拥有较好的应用潜力。本文综述了含末端氨基配体的PCPs材料应用于二氧化碳捕捉及存储的代表性工作,并对所存在的问题及发展方向进行了分析总结。     

Microfabricated porous glass channels for electrokinetic separation devices

Electrically insulated porous SiO2 channels for electrokinetic separation devices were fabricated based on a mask-less etching process for creation of high aspect ratio needles in silicon. The silicon needles are converted to SiO2 by oxidation and integrated within the interior of a fluidic channel network. The channels are about 5 microm high with a pore size of 0.5+/-0.2 microm. An electrophoretic separation of a mixture of fluorescein and 5-carboxyfluorescein using epi-fluorescence detection was performed to verify proper electrokinetic transport in the porous channels. The plate height was about 170,000 m-1 for a field strength of 170 V cm-1. In the near future, it is intended to extend the fabrication scheme to include an array of porous pillars for capillary electrochromatography experiments.