Electrosprayed porous microspheres for the removal of endocrine disruptors

Polyethersulfone (PES) porous microspheres were prepared via electrospraying technique, and then were used for the removal of endocrine disrupters from aqueous solutions. The surface and the internal structures of electrosprayed microspheres were characterized by scanning electron microscopy (SEM) and the results showed that they were porous. The electrosprayed porous PES microspheres can remove biphenyl A and biphenyl effectively. At the same time, they showed larger adsorption capacity and fast kinetics of uptaking target species than PES injected spheres reported in the earlier publications. The hydrophilicity and porosity of electrosprayed microspheres can be controlled by changing the amount of hydrophilic polyethylene glycol (PEG), which influences the adsorption properties of the microspheres. The results showed that electrosprayed porous PES microspheres have the potential to be used in the environmental application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

静电纺丝法制备多孔超细聚醚砜纤维及其对双酚A的吸附性能

创新性地将静电纺丝法技术和沉浸凝胶方法相结合,制备了多种不同结构的多孔超细聚醚砜(PES)纤维,将多孔超细纤维运用于水溶液中环境激素双酚A(BPA）的吸附,并考查了多孔超细PES纤维对环境激素BPA的吸附机理。结果表明,以聚乙二醇(PEG）为致孔剂得到的多孔超细纤维的孔洞小而分布均匀,以聚乙烯醇(PVA）为致孔剂产生的多孔超细纤维的孔洞大且发生了取向;接收方式对以PVA为致孔剂的多孔超细PES纤维形貌影响大,空气浴中接收到的是多孔超细纤维,水浴中接收到的是中空多孔超细PES纤维;多孔超细PES纤维对环境激素BPA的动态吸附符合伪二阶动力学模型,等温吸附符合Freundlish等温模型。     

Electrospinning of thermo-regulating ultrafine fibers based on polyethylene glycol/cellulose acetate composite

Ultrafine fibers of polyethylene glycol/cellulose acetate (PEG/CA) composite in which PEG acts as a model phase change material (PCM) and CA acts as a matrix, were successfully prepared as thermo-regulating fibers via electrospinning. The morphology observation from the electrospun PEG/CA composite fibers revealed that the fibers were cylindrical and had a smooth external surface. PEG was found to be both distributed on the surface and within the core of the fibers. Differential scanning calorimeter (DSC) was used to characterize the thermal properties of the composite fibers. The results indicated that the fibers imparted balanced thermal storage and release properties for their thermo-regulating function and the thermal properties were reproducible after 100 heating-cooling cycles.     

Characterization of Surface Modification of Polyethersulfone Membrane

Surface modification of polyethersulfone (PES) membrane surfaces using UV/ozone pretreatment with subsequent grafting and interfacial polymerization on membrane surface was investigated in order to improve the resistance of membrane surface to protein adsorption. The surface modifications were evaluated in terms of hydrophilicity, chemical composition of the surface and static protein adsorption. In both methods, poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG) and chitosan were chosen as hydrophilic polymers to chemically modify the commercial virgin PES membrane to render it more hydrophilic as these materials have excellent hydrophilic property. Modified PES membranes were characterized by contact angle and XPS. Contact angles of modified PES membranes were reduced by 19 to 58% of that of the virgin PES membrane. PES membrane modified with PEG shows higher wettability than other hydrophilic materials with the highest contact angle reduction shown for UV/ozone pretreated, PEG grafted PES membrane surface. In general, XPS spectra supported that the PES membranes were successfully modified by both grafting with UV/ozone pretreatment and interfacial polymerization methods. The results of the static protein adsorption experiments showed all surface modifications led to reduction in protein adsorption on PES membranes; the highest protein adsorption reduction occurred with membrane modified by UV/ozone pretreatment followed by PES grafting, which corresponded to the highest contact angle reduction. However, there seems to be no clear correlation between contact angle reduction and reduction in protein adsorption in the case that involved chitosan. Nevertheless, membranes modified with chitosan do show higher reduction in protein adsorption than membranes modified with other materials under the same conditions.     

Surface modification of polyethersulfone hollow-fiber membranes by γ-ray irradiation

The fouling of ultrafiltration membrane is often caused by gel formation on the membrane surface. This gel layer arises due to concentration polarization or macromolecular adsorption on the membrane surface. The gel layer affects both the hydraulic permeability and the rejection properties of the membrane. In this report, the adsorption of porcine albumin and the concentration polarization effect on modified and unmodified polyethersulfone (PES) hollow-fiber membrane is studied. PES ultrafiltration hollow-fiber membranes were modified by the grafting of polyethylene glycol (PEG) polymer on the internal surface using γ-ray irradiation method. The modified hollow fibers were less susceptible to fouling than were the unmodified fiber. The performance of both modified and unmodified hollow fibers was tested as a function of feed flow rates and protein concentrations. © 1994 John Wiley & Sons, Inc.     

静电纺超细相变纤维的研究进展

相变纤维(PCF)已被广泛研究并用作高性能非织造布和涂料。随着纤维制造技术的发展,静电纺超细PCF已经被开发和研究。综述了静电纺丝技术对超细(亚微米)PCF的研究和发展状况。讨论了使用长链脂肪烃(或石蜡)、聚乙二醇、脂肪酸(及其共晶体)和其它固液相变材料(PCM)作为潜热储存材料的静电纺超细PCF的形态、组成和热性质,为制造具有所需热物理性质的超细PCF提供指导。     

聚酰胺6蓄热调温纤维的制备与表征

以聚乙二醇为储能调温介质,通过多孔纳米材料吸附制备了形态稳定的相变材料(PCMS),然后以聚酰胺6(PA6)为基体,采用熔融共混纺丝制备了蓄热调温PA6纤维。通过场发射扫描电子显微镜、差示扫描量热仪、热重分析仪、粉末X射线衍射仪表征了纤维的结构和性能。研究表明:熔纺PA6/PCMs纤维储能调温焓值达到19.01 J/g,预期可在航空服、军用作战服和民用服装等领域获得很好的应用。     

Effect of additives concentration on performance of cellulose acetate and polyethersulfone blend membranes

Asymmetric micro porous membranes have been prepared successfully from blending of cellulose acetate (CA) and polyethersulfone (PES) by the phase inversion method with N, N-dimethylformamide (DMF) as solvent. Two additives were selected in this study, including polyethylene glycol 600 (PEG 600) and polyvinylpyrrolidone (PVP). The effects of concentration of additives on CA/PES blend membrane performance and cross-section morphology were investigated in detail. CA/PES membranes were compared with CA/PES/PEG and CA/PES/PVP membranes in the performance such as pure water flux, membrane resistance, porosity and cross-section morphology. The resulting blend membranes were also carried out the rejection and permeate flux of Egg Albumin (EA) proteins with molecular weight of 45 Da. The membranes thus obtained with an additive concentration of 5 wt% of both PEG and PVP exhibited superior properties than the 80/20% blend composition of CA and PES membranes. The permeate flux of protein was increased from 44 to 134 lm² h with increase in concentrations of both PVP and PEG in 80/20% blend composition of CA and PES membranes. Cross-sectional images from scanning electron microscopy showed larger macropores in the bottom layer of the membranes with increasing additives content. Observations from scanning electron microscopy provided qualitative evidence for the trends obtained for permeability and porosity results.     

Effect of benzyl triethylammonium chloride on microstructure of bicomponent polymeric fibers during electrospinning

Effect of benzyl triethylammonium chloride (BTEAC) on the microstructure of electrospun bicomponent fibers, i.e., polyvinylidene fluoride (PVDF)/polycarbonate (PC), polyacrylonitrile (PAN)/polyethylene glycol (PEG), and PAN/PVDF, was investigated in this article. The evolution of morphology and microstructure of the above bicomponent fibers were examined by scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The results showed that distinct core/shell structured fibers were successfully prepared from PVDF/PC and PAN/PVDF via introducing a small amount of BTEAC, whereas only cocontinuous structure was detected in the electrospun PAN/PEG fibers. This study could be an example of electrospun multipolymer dispersions influencing by an organic salt, and it could be extended to control the structure of carbon nanofibers via electrospinning. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

The effects of processing parameters on the morphology of PLA/PEG melt electrospun fibers

Electrospinning of a polymer melt is an ideal technique to produce highly porous nanofibrous or microfibrous scaffolds appropriate for biomedical applications. In recent decades, melt electrospinning has been known as an eco‐friendly procedure as it eliminates the cytotoxic effects of the solvents used in solution electrospinning. In this work, the effects of spinning conditions such as temperature, applied voltage, nozzle to collector distance and collector type as well as polyethylene glycol (PEG) concentration on the diameter of melt electrospun polylactic acid (PLA)/PEG fibers were studied. The thermal stability of PLA/PEG blends was monitored through TGA and rheometry. Morphological investigations were carried out via optical and scanning electron microscopy. Based on the results, blends were almost stable over the temperature range of melt electrospinning (170 ? 230 °C) and a short spinning time of 5 min. To obtain non‐woven meshes with uniform fiber morphologies, experimental parameters were optimized using ANOVA. While increasing the temperature, applied voltage and PEG content resulted in thinner fibers, PEG concentration was the most influential factor on the fiber diameter. In addition, a nozzle to collector distance of 10 cm was found to be the most suitable for preparing uniform non‐woven PLA/PEG meshes. At higher PEG concentrations, alterations in the collector distance did not affect the uniformity of fibers, although at lower distances vigorous bending instabilities due to polarity augmentation and viscosity reduction resulted in curly fibrous meshes. Finally, the finest and submicron scale fibers were obtained through melt electrospinning of PLA/PEG (70/30) blend collected on a metallic frame. © 2017 Society of Chemical Industry     

聚乙二醇/SiO2定形相变材料在沥青中的相变储热性能

利用多孔二氧化硅的良好吸附性,将不同计量的聚乙二醇在硅溶胶胶凝过程中吸附于硅凝胶的孔隙结构中制备聚乙二醇/二氧化硅定形相变材料（PEG/SiO₂ SSPCM）;并将其与熔融沥青共混获得不同聚乙二醇含量的沥青-定形相变材料（Asphalt-SSPCM）。借助孔径分析仪和扫描电镜（SEM）表征了载体二氧化硅孔结构和PEG/SiO₂ SSPCM的表观形貌;通过X射线衍射仪（XRD）、综合热分析仪（DSC/TG）和傅里叶红外光谱仪（FTIR）考察了沥青中PEG/SiO₂ SSPCM的晶体结构、储热性能、热稳定性及化学兼容性;通过本文作者课题组研发的温度模拟试验箱测试了Asphalt-SSPCM的降温效果。结果表明,二氧化硅凝胶具有丰富的孔结构并能将聚乙二醇吸附于其介孔结构中;沥青中PEG/SiO₂ SSPCM仍含有聚乙二醇晶体,其储热能力随聚乙二醇含量的增加而增大,当聚乙二醇含量为76.1%时,相变焓高达117.5J/g,且不同聚乙二醇含量的沥青-定形相变材料均表现出良好的热稳定性;PEG/SiO₂ SSPCM与沥青的化学兼容性良好,二者之间仅是物理作用;Asphalt-SSPCM的降温效果显著,可有效改善沥青路面的高温性能;并基于相变理论,分析了沥青-定形相变材料的相变储热原理。     

Experimental Investigation on the Characteristics of Polyethylene Glycol/Cement Composites as Thermal Energy Storage Materials

The polyethylene glycol/cement composites as thermal energy storage materials were prepared by blending polyethylene glycol and cement. In composite materials, polyethylene glycol (PEG) is used as the phase change material for thermal energy storage and cement acts as the supporting material. A Fourier transformation infrared spectroscope (FT‐IR), x‐ray diffractometer (XRD), and scanning electronic microscope (SEM) were used to determine the chemical structure, the crystalloid phase, and microstructure of the polyethylene glycol/cement composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The SEM results showed that the polyethylene glycol was well dispersed in the porous network of the cement.     

Preparation and properties of modified PHEMA hydrogel with sulfonated PEG graft

A novel poly(ethylene glycol) (PEG) macromer with a methacryloyl and sulfonic acid group at each end of the chain was prepared. Modified hydroxyethyl methacrylate (HEMA) based hydrogels were synthesized by crosslinking polymerization of HEMA in the presence of the above‐mentioned PEG macromer. The effect of the sulfonated PEG graft was examined by comparing the swelling properties with those of a pure poly(hydroxyethyl methacrylate) (PHEMA) hydrogel. The modified PHEMA hydrogel exhibited increasing water absorbency with increasing sulfonated PEG content up to 15 wt %. These hydrogels with the sulfonated PEG graft exhibited a more hydrophilic character than the pure PHEMA gel. Also the swelling degree varied slightly with pH, showing increased swelling at higher pH probably due to the presence of the anionic sulfonate group on the PEG end chain. In addition, the protein adsorption test showed a lower level of fibrinogen adsorption from the sulfonated poly(ethylene glycol) (SPEG) modified gel than on the homo PHEMA hydrogel. Interestingly, scanning electron microscopy showed that the porous and rather uniform morphology of the gels changed with increasing sulfonated PEG content in PHEMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2484–2489, 2007     

Role of Mn of PEG in the morphology and properties of electrospun PEG/CA composite fibers for thermal energy storage

As an aim toward developing novel class of form‐stable polymer‐matrix phase change materials for thermal energy storage, ultrafine composite fibers based on cellulose acetate and polyethylene glycol (PEG) with five different molecular weight (M_n) grades were prepared by electrospinning. The effects of M_n of PEG on morphology, thermal properties and mechanical properties of the composite fibers were studied by field emission scanning electron microscopy, differential scanning calorimetry, and tensile testing, respectively. It was found that the composite fibers were smooth and cylindrical shape, with the average diameters ranging from about 1000 to 1750 nm which increased with M_n of PEG. Thermal analysis results showed that the composite fibers imparted balanced thermal storage and release properties in different temperature ranges with the variation of M_n of PEG. Thermal cycling test indicated that the prepared composites had excellent thermal stability and reliability even they were subjected to 100 heating‐cooling thermal cycles. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Study of electrospun polyacrylonitrile fibers with porous and ultrafine nanofibril structures: Effect of stabilization treatment on the resulting carbonized structure

Electrospun polyacrylonitrile (PAN)-based carbon nanofibers (CNFs) with high surface area have been of promising interest because of their potential for applications in various fields, especially energy devices. In this study, PAN nanofibers with porous and ultrafine nanofiber structures were prepared by electrospinning PAN/poly(vinyl pyrrolidone) (PVP) immiscible solutions and then selectively removing the PVP component from the electrospun PAN/PVP bicomponent nanofibers. The chemical reaction and microstructure of the PAN fibers with porous and ultrafine nanofibril structures in the stabilization process were investigated. The results revealed the effects of PAN fibers with porous and ultrafine nanofibril structures on the crosslinking reaction, microstructure, and morphology during the stabilization process. According to the in situ Fourier transform infrared spectroscopy results, the intermolecular and intramolecular reactions of the nitrile group for the PAN fibers with ultrafine nanofibril structures exhibited slower reaction rates than those for the neat PAN fibers during stepwise and isothermal heating. Selecting a good stabilization temperature for ultrafine PAN-crosslinked nanofibrils can enhance the surface area and carbonized structure of CNFs. The possible applications of CNFs with porous and ultrafine nanofibril structures in supercapacitors were also evaluated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48218.     

Control of structure and morphology of highly aligned PLLA ultrafine fibers via linear-jet electrospinning

In this work, poly(l-lactic acid) (PLLA) ultrafine fibers with different morphology and structure were fabricated by a novel linear-jet electrospinning method which relies on a conventional electrospinning set-up with continuous rotating drum. To control the morphology and structure of PLLA electrospun fibers, different solution systems and electrospinning conditions were investigated. Two PLLA solution systems (PLLA/DMF/CH₂Cl₂ and PLLA/CH₂Cl₂) with different concentration and conductivity were used for the electrospinning and their influences on the formation of the linear electrospinning jet were discussed. Two types of collecting patterns with aligned buckling and linear structure were achieved under the linear electrospinning jet. Highly aligned PLLA electrospun fibers with porous surface could be formed by using the highly volatile solvent CH₂Cl₂. Here, it should be emphasized that the diameter and surface porosity of such highly aligned PLLA electrospun fibers can be fine tuned by varying the winding velocity. The results of SEM images and polarized FTIR investigations verified that the as-spun PLLA porous surface fibers were highly aligned and molecularly oriented, leading to the enhanced mechanical performance as compared to the non-woven PLLA electrospun fibers.     

大孔吸附树脂XAD-4对聚乙二醇的吸附性能

以大孔吸附树脂XAD-4为吸附剂,采用静态平衡吸附法吸附模拟聚乙二醇(PEG)废水,考察了初始pH值、吸附时间、吸附剂投加量和温度等因素对PEG去除效果的影响. 结果表明,pH值对吸附过程的影响可忽略不计. 当XAD-4树脂投加量为0.3 g/L时,PEG去除率可达89%,平衡吸附量Qe=59.95 mg/g. PEG在XAD-4树脂表面上均一分布,Langmuir, Dubinin-Radushkevich和Sips模型可较好地模拟其等温吸附过程. 不同温度下均为自发的放热吸附过程. 动态吸附数据符合拟二级动力学方程.     

Fabrication of ultrafine fibers of poly(γ-glutamic acid) and its derivative by electrospinning

Poly(γ-glutamic acid) (PGA) was successfully electrospun by the addition of poly(ethylene glycol) (PEG) and Triton X-100 in its aqueous solution to produce the PGA non-woven mat of the ultrafine fibers. The average fiber diameter was in the range between 200 nm and 2 μm. The fiber mat was quickly soluble in water due to the large surface area of the fibers. The electrospinning of PGA butyl ester with the esterification degree of 61% in 1,1,1,3,3,3-hexafluoro-2-propanol gave the water-insoluble nanofiber mat.     

聚醚砜的静电纺丝研究

采用聚醚砜(PES)的良溶剂二甲基甲酰胺(DMF)和非良溶剂丙酮(AC)为共溶剂体系,研究了溶剂组成、纺丝成形条件对静电纺丝PES纤维的形貌及纤维直径的影响。结果表明:DMF/AC的配比对于静电纺丝PES纤维形貌具有直接的调控作用,随着DMF/AC混合溶剂中AC用量的增加,纤维平均直径变大,纤维毡中串珠数目明显减少,纤维均一性变好;随着纺丝液浓度的升高,纺丝电压的增大,纤维的平均直径变大;接收距离的变化对纤维平均直径影响不大;PES最佳纺丝工艺条件为纺丝溶液质量分数13%,纺丝电压15 kV,接收距离10 cm,mDMF/mAC为8.5/1.5,在此条件下,可以获得纤维平均直径为96 nm的PES纤维毡。     

基于均匀设计优化制备静电纺丝相变储湿纤维

以醋酸纤维素为包裹材料、聚乙二醇800为相变材料、N,N-二甲基乙酰胺和丙酮为溶剂,采用静电纺丝法制备相变储湿纤维。基于均匀设计和多元非线性回归法研究了各因素对静电纺丝相变储湿纤维综合热-湿性能的影响。结果表明,各因素对性能影响的主次顺序为：聚乙二醇800用量＞N,N-二甲基乙酰胺用量＞醋酸纤维素用量＞反应温度＞干燥温度;优化制备方案：N,N-二甲基乙酰胺用量为11.3 g、醋酸纤维素用量为6.96 g、聚乙二醇800用量为8.12 g、反应温度为37.8 ℃、干燥温度为60.4 ℃.