水溶性聚乙烯醇纳米纤维毡的制备与表征

采用静电纺丝技术制备了聚乙烯醇(PVA)纳米纤维毡,主要考察了纺丝液浓度和纺丝电压对静电纺纤维形成及其微观形貌的影响。实验结果表明:纺丝液的浓度对纤维的形成和形貌起着决定性作用,随着PVA质量分数的增加,在纺丝过程中纺丝液逐渐从液滴转变为均匀的纤维,纤维直径逐渐增加,当纺丝液的PVA质量分数为6%时,纤维形貌最佳;随着纺丝电压的提高,纤维平均直径先是有一定程度的降低,但随后降低幅度变得很小。通过实验确定了制备PVA纳米纤维毡的最佳工艺为:纺丝液的PVA质量分数6%,纺丝电压18kV,接收距离11cm,挤出速度0.5ml/h。     

Emulsion electrospinning: Fundamentals,food applications and prospects

BackgroundIn the past decades, many natural bioactive compounds with antioxidant, immunoregulatory, antimicrobial, and anticancer activities have been successfully identified in plant and animal materials. However, due to their poor solubility, unfavorable flavor, low bioavailability and instability during food processing and storage, the development of bioactive compounds used in the food industry presents many technological challenges.Scope and approachEmulsion electrospinning is a novel and simple technique to fabricate core-shell nanofibers, and either water-in-oil (W/O) or oil-in-water (O/W) emulsions can be electrospun to directly encapsulate hydrophilic or hydrophobic compounds into core-shell fibers, respectively. This review introduces fundamentals and advantages of emulsion electrospinning as well as its food applications. The effects of different types of emulsifiers on the formation of emulsion systems and emulsion-based electrospun fibers are highlighted. Further, the existing limitations and scope for future research are discussed.Key findings and conclusionsRecent studies have found that the emulsion-based electrospun nanofibers can enhance the encapsulation efficiency, stability, and bioavailability of bioactive compounds, as well as achieve targeted delivery and controlled release, thus providing new strategies to improve their barrier performance compared to conventional electrospinning and therefore facilitating the development of emulsion-based electrospun mats in the food industry.     

可见光响应聚丙烯腈纤维膜的制备及其光催化性能

通过静电纺丝及后续的水热处理工艺制备载有二氧化钛的聚丙烯腈纤维膜,该纤维膜具有可见光响应光催化性能。静电纺丝得到的初生纤维中含有钛酸四丁酯、硝酸钆、聚丙烯腈和聚乙烯吡咯烷酮,纤维表面光滑(直径约为320 nm)。再将初生纤维膜置于特氟龙水热釜中进行水热处理;纤维变成表面凹凸不平的多孔纤维(直径约为350 nm,BET比表面积为17.45 m2/g);结合XPS和XRD测试结果证实载有anatase相二氧化钛(Gd/N-Ti O2)晶体的聚丙烯腈纤维膜制备成功。在室温条件下,这种有机/无机杂化纤维膜对罗丹明B水溶液具有明显的可见光降解效果。     

Electrospinning and characterization of poly (vinyl alcohol)–sericin nanofibers as a potential for tissue engineering applications

Poly vinyl alcohol (PVA) is a hydrophilic, biocompatible, and biodegradable polymer which has found application in biodrugs and tissue engineering. Sericin accompanying silk is a waste which is produced in scouring silk and has interesting properties which has attracted the attention of researchers. Silk sericin is also hydrophilic, biodegradable, and biocompatible. Moreover, it is cheap and anti-cancerous. Mixture of PVA and sericin in the form of 2D membrane or 3D hydrogels has been employed to heal skin damages. This research aimed at electrospinning PVA–sericin blend nanofibers in the form of a mat which has applications in tissue engineering, using dimethyl sulfoxide (DMSO) as an organic solvent. This research showed that the solution of PVA–sericin in DMSO was electrospinnable; however, the addition of urea to the solution made the electrospinning easier. The electrospinning solution contained ratio of 0:100, 10:90, 15:85, 20:80, and 25:75 sericin (%w/w)–PVA (%w/w). The electrospun PVA–sericin nanofibers had an average diameter in the range of 179–285 nm. X-ray diffractometer and differential scanning calorimetry investigations showed no reaction occurring between PVA and sericin. Polyvinyl alcohol 100% was also electrospun in DMSO. Up to now, the electrospinning of PVA in non-aqueous media has not been reported in the literature.     

J. Cosmet. Sci., 59, 233–242 (May/June 2008) Electrospun poly (vinyl alcohol) fiber mats as carriers for extracts from the fruit hull of mangosteen

Electrospinning is a process used to produce ultrafine fibers with diameters in the nanometer range. Electrospun fiber mats have high potentials for biomedical uses, due to their high surface area and ease of drug incorporation into the fibers. They can be used as carriers for drug delivery and can enhance drug release and skin permeability. The aim of this study was to prepare electrospun fiber mats and to incorporate extracts from the fruit hull of mangosteen. Anti-oxidant activity and extract release were determined and compared between the extract incorporated in the electrospun fiber mats and in the cast films. Poly (vinyl alcohol) (PVA) was selected as the polymer matrix. Extracts in the amount of 2.5%, 5%, and 10% w/w, based on the weight of PVA, were incorporated with 10% w/w PVA to finally obtain electrospun fiber mats and cast films. The extract content was evaluated by anti-oxidative activity using the 2,2-diphenyl-1picryhydrazyl (DPPH) method. The morphology of the electrospun fiber mats was analyzed using a scanning electron microscope (SEM). The results showed that the diameters of the fibers were in nanoscales and that no crystal of the extract was found at any concentration of the extract. The extract contents in the electrospun fiber mats prepared at 2.5%, 5%, and 10% w/w of the extract were 9.6%, 9.7%, and 10.8% of the initial loading concentration, respectively, whereas, those in the cast films were 23.9%, 14.5%, and 21.0%, respectively. The release of the extract from the electrospun fiber mats prepared at 2.5%, 5%, and 10% w/w of the extract at 120 min were 73.2%, 83.6%, and 81.3% w/w, respectively. However, much slower release from the cast films was observed (i.e. 4.3%, 29.1%, and 40.8% w/w, respectively).     

Adhesion and protective properties of polyvinyl alcohol nanofibrous composite fabrics

To avoid the separation of nanofiber mats and substrates during post-processing, the substrate was pretreated by plasma before electrospinning. Polyvinyl alcohol (PVA) nanofiber mats were deposited on the habutae, polyester-taffeta, and nylon-taffeta fabrics by a needless electrospinning setup with spiral disk spinnerets. The effects of plasma treatment on the adhesion of electrospun PVA nanofibrous composite fabrics were studied. The aerosol particles protective performance and wearabilities were also investigated as a function of the thickness of electrospun PVA nanofiber mat. Results showed that the surface nanoscale concave–convex roughness of substrate fabric was formed after oxygen plasma treatment. The peeling strength and peeling energy increased with the increase in surface roughness in a limited range. The peeling energy of PVA/nylon-taffeta enhanced to 2.97 times when nylon-taffeta treated by oxygen plasma at 200 W for 3 min. The aerosol particle filtration efficiency enhanced with the increase in electrospinning time, and the quality factor of PVA/nylon-taffeta was the highest with electrospinning for 10 min. Simultaneously, the air permeability and the water vapor transmission rate of PVA/nylon-taffeta decreased with the increase in electrospinning time, whereas the drape coefficient increased.     

交联PVA与未交联PVA纳米纤维膜的结构比较

利用静电纺丝法制备交联PVA纳米纤维和未交联PVA纳米纤维,对其制作工艺、结构等进行了比较。在硫酸作为催化剂的条件下,PVA纤维能有效通过顺丁烯二酸酐（MA）进行交联。采用扫描电镜法（SEM）、红外光谱法（FTIR）、差热扫描法（DSC）对PVA粉末、未交联PVA纳米纤维膜以及交联PVA纳米纤维膜的形态和结构进行了研究。     

静电纺短纤维的制备及其生物医学应用

传统静电纺纳米纤维常作为组织工程支架被用于修复缺损部位,往往必须借助外科手术有创植入,极大限制了其在生物医学领域中的应用。为促进静电纺丝技术的开发和应用,综述了静电纺短纤维的制备及其功能化的方法,分类介绍了功能化短纤维在诊断检测、治疗和组织工程这3个方面的生物医学应用;系统分析通过调节工艺参数、后续加工等方式保留静电纺纳米纤维膜的内在功能,以及基于其小尺寸和单分散性,避免纤维膜植入所造成的机体侵入创伤;最后,结合静电纺短纤维当前发展情形分析了其在生物医学领域应用中所面临的挑战和未来的发展前景。     

氯化锂对静电纺PVA溶液稳定段射流的影响

静电纺丝过程中,当溶液完全绝缘或施加电压不够高时,静电力不能克服溶液的表面张力,纺丝无法进行。为克服这个问题,在溶液中加入盐。用聚乙烯醇纺丝液,当添加的LiCL质量分数不同时,纺得的纳米纤维直径从大到小排列顺序为：1% LiCl>0.8% LiCl>0.5% LiCl>0.2% LiCl。研究了LiCl质量分数对于轴向坐标的射流半径的影响机制,推导出直线段（稳定段）部分射流半径与轴向坐标符合如下关系, 的关系,并通过测量添加不同质量分数LiCl的聚乙烯醇纺丝液的射流半径进行实验验证,结果表明实验值与理论值完全吻合。     

丝素蛋白/醋酸纤维素共混纤维毡的制备与表征

将不同质量比的丝素蛋白（SF）/醋酸纤维素（CA）溶于甲酸中,配置成共混溶液进行静电纺丝,得到SF/CA共混纤维毡。利用SEM、XRD对其结构进行测试表征。结果表明：SF中添加少量CA(<10%),SF的可纺性显著提高,添加10%CA时,可纺性最好,所得共混电纺纤维细且均匀,直径为50～300nm;CA添加量大于30% 时,可纺性恶化,出现大量的珠状物,且纤维粘连、不连续,形成树枝状结构。XRD分析表明,添加少量CA(<10%)能诱导SF分子构象由无规卷曲向β折叠转变,但CA添加量大于30%时,SF与CA两者分相。     

氯化锂对静电纺聚丙烯腈纳米纤维结构的影响

静电纺丝是用聚合物溶液或熔体制取纳米纤维的简易方法。当溶液完全绝缘或施加电压不够高时,静电力无法克服表明张力,纤维纺不出来。溶液中加盐后,就能克服这个问题。添加不同质量分数LiCl的聚丙烯腈纺丝液纺得纳米纤维的直径从大到小排列为:4%LiCl>3%LiCl>2%LiCl>1%LiCl。对纺得的纳米纤维内部结构采用X射线衍射和红外光谱法进行分析,发现加盐有利于静电纺丝且不会影响纳米纤维的内部结构。     

静电纺丝拉伸模型与实验

利用珠链纤维模型对静电场作用下聚合物溶液的纺丝拉伸过程进行模拟,通过计算纺丝过程中聚合物射流细度随时间的动态变化,可得到不同工艺条件下所纺纤维的直径。为了验证模型的可行性,采用聚乙烯醇溶液进行静电纺丝实验,初步探讨纤维细度与接收距离之间的关系。实验结果表明,当接收距离在14~40 cm范围内,纤维直径随接收距离的增加有逐渐变细的趋势。通过与模拟结果的对比可以看出,在接收距离小于30 cm时,实验数据和模拟结果吻合较好。     

High flux filtration medium based on nanofibrous substrate with hydrophilic nanocomposite coating

A novel high flux filtration medium, consisting of a three-tier composite structure, i.e., a nonporous hydrophilic nanocomposite coating top layer, an electrospun nanofibrous substrate midlayer, and a conventional nonwoven microfibrous support, was demonstrated for oil/water emulsion separations for the first time. The nanofibrous substrate was prepared by electrospinning of poly(vinyl alcohol) (PVA) followed by chemical cross-linking with glutaraldehyde (GA) in acetone. The resulting cross-linked PVA substrates showed excellent water resistance and good mechanical properties. The top coating was based on a nanocomposite layer containing hydrophilic polyether-b-polyamide copolymer or a cross-linked PVA hydrogel incorporated with surface-oxidized multiwalled carbon nanotubes (MWNTs). Scanning electron microscopy (SEM) examinations indicated that the nanocomposite layer was nonporous within the instrumental resolution and MWNTs were well dispersed in the polymer matrix. Oil/ water emulsion tests showed that this unique type of filtration media exhibited a high flux rate (up to 330 L/m2-h at the feed pressure of 100 psi) and an excellent total organic solute rejection rate (99.8%) without appreciable fouling. The increase in the concentration of surface-oxidized MWNT in the coating layer generally improves the flux rate, which can be attributed to the generation of more effective hydrophilic nanochannels for water passage in the composite membranes.     

聚合物静电纺及在组织工程支架中的应用

1.浙江理工大学材料与纺织学院 浙江杭州310018 ;2.浙江大学高分子复合材料研究所 浙江杭州310027;3.浙江大学教育部高分子合成与功能构造重点实验室 浙江杭州310027     

Synthesis of DBSA-doped Polyaniline by Emulsion Polymerization and PANI/PLA Electrospun Fiber Membrane Conductivity

Polyaniline (PANI) has gained interest due to its reasonably good conductivity, stability, easy preparation, affordability, and redox properties. Aniline monomers, emulsifiers, and dopant DBSA are used for emulsion polymerization in water, using various oxidants. The DBSA-doped polyaniline was extracted via a chloroform solution, and PLA was added directly in the emulsion to form the DBSA-PANI/PLA composite electrospinning solution. The DBSA-PANI/PLA composite nanofiber membrane was prepared via electrospinning. FeCl₃, K₂Cr₂O₇, and ammonium persulfate were used as oxidants in the emulsion polymerization process. The Infrared spectra showed the full characteristic peaks of polyaniline when ammonium persulfate was used as an oxidant. The transmission rate of the characteristic peak became smaller when the ratio of ammonium persulfate/aniline monomer increased from 0.5 to 1, demonstrating the polyaniline content increased. The electrospun nanofibers that were prepared were spindle-shaped fibers and the fiber diameter distribution was wide. The PANI/PLA electrospun fiber membrane conductivity was several orders of magnitude higher than the pure PLA membrane. The PANI/PLA electrospun fiber membrane had the highest conductivity (9.1 × 10^-3 S/cm) when (APS/An) = 1.0. This prepared PANI/PLA nanometer fiber membrane could be used for electromagnetic shielding and could be an effective biomaterial within the engineering of electrically responsive biological tissues and organs.     

乳液静电纺丝美藤果油/聚乙烯醇纳米纤维膜的制备及性能

采用乳液静电纺丝法制备基于美藤果油/聚乙烯醇（polyvinyl alcohol,PVA）乳液的具有核壳结构的纳米纤维及纤维膜,为促进美藤果油在食品领域的进一步应用提供基础,并促进美藤果油作为新资源食品的高值化利用。通过电导率仪和黏度计测定乳液的电导率和黏度,利用扫描电子显微镜和透射电子显微镜观察纳米纤维膜形貌,并对乳液组分比例、纺丝参数进行调整优化;通过热特性和傅里叶变换红外光谱表征分析纳米纤维膜的各组分及作用;利用接触角测量仪测试纳米纤维膜表面的亲水性能;使用抗拉强度测量仪测定纳米纤维膜的机械性能。结果表明：制备美藤果油/PVA纤纳米纤维膜的乳液最佳配比为PVA质量分数14%,美藤果油、PVA、吐温-80的最佳质量比为5∶14∶1;最佳纺丝条件为电压25 kV、接收距离18 cm、供液速率1.0 mL/h。在最佳条件下纺丝,可得到平均直径为570 nm且形貌良好、分布均匀的纳米纤维。傅里叶变换红外光谱和热特性分析结果表明所制得的纳米纤维成功地封装了美藤果油,并在低于330 ℃的温度条件下表现出良好的热稳定性。接触角测量结果表明纳米纤维膜表面具有良好的亲水性能。机械性能分析结果表明美藤果油的添加可以提高纳米纤维膜的拉伸性能。     

Electrospun zein/PVA fibrous mats as three-dimensional surface for embryonic stem cell culture

This paper reports a new method of producing electrospun zein/polyvinyl alcohol (PVA) mats as three-dimensional (3D) cell culture surface material. The electrospun structure has many advantages and protein-based biomaterials possess unique properties preferred for cell biocompatibility. However, electrospun fiber matrices developed from proteins have poor mechanical properties and morphological stability in the aqueous environments required for cell culture. Efforts have been made to improve the properties of electrospun protein scaffolds, including dry mechanical for handling and surface hydrophilicity, but the current methods have major limitations, such as cytotoxicity and low efficiency. In this research, experimental data showed that the adding different proportion of PVA influenced the properties of the zein mats. Considering the properties of the mats and mouse embryonic stem cells growth behavior on the various electrospun mats, the EM3 (zein/PVA with mass ratios of 3:1) showed better growth status than any other mats. EM3 affixed to cover-glass could be autoclaved for 30?min at 120°C. In addition, embryonic stem cells cultured on chosen electrospun zein/PVA mats in vitro proved that culture products were easily attached onto mat and mat could be used for induction of stem cell differentiation and therefore promising mats for 3D cell culture surface applications.     

Fabrication, functionalization, and application of electrospun biopolymer nanofibers

The use of novel nanostructured materials has attracted considerable interest in the food industry for their utilization as highly functional ingredients, high-performance packaging materials, processing aids, and food quality and safety sensors. Most previous application interest has focused on the development of nanoparticles. However, more recently, the ability to produce non-woven mats composed of nanofibers that can be used in food applications is beginning to be investigated. Electrospinning is a novel fabrication technique that can be used to produce fibers with diameters below 100 nm from (bio-) polymer solutions. These nanofibers have been shown to possess unique properties that distinguish them from non-woven fibers produced by other methods, e.g., melt-blowing. This is because first the process involved results in a high orientation of polymers within the fibers that leads to mechanically superior properties, e.g., increased tensile strengths. Second, during the spinning of the fibers from polymer solutions, the solvent is rapidly evaporated allowing the production of fibers composed of polymer blends that would typically phase separate if spun with other processes. Third, the small dimensions of the fibers lead to very high specific surface areas. Because of this the fiber properties may be greatly influenced by surface properties giving rise to fiber functionalities not found in fibers of larger sizes. For food applications, the fibers may find uses as ingredients if they are composed solely of edible polymers and GRAS ingredients, (e.g., fibers could contain functional ingredients such as nutraceuticals, antioxidants, antimicrobials, and flavors), as active packaging materials or as processing aids (e.g., catalytic reactors, membranes, filters (Lala et al., 2007), and sensors (Manesh et al., 2007; Ren et al., 2006; Sawicka et al., 2005). This review is therefore intended to introduce interested food and agricultural scientists to the concept of nano-fiber manufacturing with a particular emphasis on the use of biopolymers. We will review typical fabrication set-ups, discuss the influence of process conditions on nanofiber properties, and then review previous studies that describe the production of biopolymer-based nanofibers. Finally we briefly discuss emerging methods to further functionalize fibers and discuss potential applications in the area of food science and technology.     

制备纳米纤维的静电纺丝接收器研究进展

静电纺丝是制备纳米纤维的重要方法,在众多领域具有较强应用价值,引起广泛关注。所得纳米纤维的取向和结构对其性能有重要影响,近年来研究主要集中于如何获得结构不同、形态各异的电纺纤维材料,以满足不同领域的使用要求。接收器作为静电纺丝装置的重要部分,决定电纺纤维的分布与组合。目前,通过对接收器进行改进已经能够制备三种基本结构电纺纤维材料,分别是排列规则纳米纤维线、图案化纳米纤维膜和三维纳米纤维体。本文简述静电纺丝原理,分别对比三种类型纳米纤维结构制备中所采用的不同接收器结构特点和收丝效果。该综述可供纳米纤维材料制备、静电纺丝装置改进和静电纺丝技术应用等研究参考。     

矩形排列四喷头喷气静电纺纳米纤维的制备

为了提高纳米纤维的产量,设计了一种矩形排列的四喷头组合式静电纺丝装置.模拟不同喷丝单元间距时的电场分布,研究了电场分布对纳米纤维的射流、产量、面积和纤维形貌的影响.研究发现,纳米纤维的产量和面积随着喷丝间距的增加先增大后减小.在喷丝单元间距为9cm时,喷丝效果最好,纳米纤维的产量最大为2.266 7g/h,喷丝面积最大.喷丝单元的间距对纤维的形貌影响不大.