静电纺丝法制备相变调温纤维及其性能

以丙酮和N,N-二甲基甲酰胺（DMF）为混合溶剂,实验室自制固-固相变材料为相变工作物质,醋酸纤维素（CDA）为高分子载体,利用静电纺丝技术制备了相变调温纤维,研究了溶剂配比、纺丝液浓度、纺丝电压等对纤维形貌的影响。结果表明：以N,N-二甲基甲酰胺（DMF）和丙酮为溶剂（体积比为1/4）,在纺丝液质量分数为22%、纺丝...     

Low‐Cost,Thermoresponsive Wettability of Surfaces: Poly(N‐isopropylacrylamide)/Polystyrene Composite Films Prepared by Electrospinning

Low‐cost, responsive poly(N‐isopropylacrylamide)/polystyrene composite films were prepared by a facile electrospinning technique. The surface structures and wettabilities of the composite films are tunable by simply controlling the concentration of polymer. With a proper proportion of each polymer, the wettability of the surface can be switched between superhydrophilicity and superhydrophobicity when the temperature is changed from 20 °C to 50 °C. The combination of a stimuli‐responsive polymer with micro/nanostructures on the surface of the composite film contributes to this unique surface property.

     

Propolis Integration Methods into Solutions for Highly Loaded Propolis Fibers by Needleless Electrospinning

A load-bearing matrix filled with biologically active compounds is an efficient method for transporting them to the target location. Bee-made propolis has long been known as a natural product with antibacterial and antiviral, anti-inflammatory, antifungal properties, and anti-oxidative activity. The aim of the research is to obtain stable propolis/PVA solutions and produce fibers by electrospinning. To increase propolis content in fibers as much as possible, various types of propolis extracts were used. As a result of the research, micro- and nano-fiber webs were obtained, the possible use of which have biomedical and bioprotective applications. All used materials are edible and safe for humans, and fiber webs were prepared without using any toxic agent. This strategy overcomes propolis processing problems due to limitations to its solubility. The integration of different combinations of extracts allows more than 73 wt% of propolis to be incorporated into the fibers. The spinning solution preparation method was adapted to each type of propolis, and by combining the methods, solutions with different propolis extracts were obtained. Firstly, the total content of flavonoids in the propolis extracts was determined for the assessment and prediction of bioactivity. The properties of the extracts relevant for the preparation of electrospinning solutions were also evaluated. Secondly, the most appropriate choice of PVA molecular weight was made in order not to subject the propolis to too high temperatures (to save resources and not reduce the bioactivity of propolis) during the solution preparation process and to obtain fibers with the smallest possible diameter (for larger surface-to-volume ratios of nanofibers and high porosity). Third, electrospinning solutions were evaluated (viscosity, pH, conductivity and density, shelf life) before and after the addition of propolis to predict the maximum propolis content in the fibers and spinning stability. Each solution combination was spun using a cylindrical type electrode (suitable for industrial production) and tested for a stable electrospinning process. Using adapted solution-mixing sequences, all the obtained solutions were spun stably, and homogeneous fibers were obtained without major defects.     

Energy Storage Properties of Phase Change Materials Prepared from PEG/CPP

Latent heat storage is one of the most efficient ways of storing thermal energy.Unlike the sensible heat storage method,the latent heat storage method provides much higher storage density,with a smaller temperature difference between storing and releasing heat.Phase change materials(PCMs)can be used for energy storage and temperature control1,2.Among them,the solid-solid phase change materials are focus of attention3,4.They can be applied in many fields such as solar energy utilization,waste…     

Colloid‐Electrospinning: Fabrication of Multicompartment Nanofibers by the Electrospinning of Organic or/and Inorganic Dispersions and Emulsions

Solution‐, melt‐, and co‐axial electrospinning are well‐known methods for producing nano‐ and microfibers. The electrospinning of colloids (or colloid‐electrospinning) is a new field that offers the possibility to elaborate multicompartment nanomaterials. However, the presence of colloids in the electrospinning feed further complicates theoretical predictions in a system that is dependent on chemical, physical, and process parameters. Herein, we give a summary of recent important results and discuss the perspectives of electrospinning of colloids for the synthesis and characterization of multicompartment fibers.     

Polymorphism Control of Poly(vinylidene fluoride) through Electrospinning

Polymorphism control of PVDF has been realized through electrospinning. PVDF fibrous membranes with fiber diameter in the range of 100 nm to several micrometers were produced by electrospinning and the crystal phase of electrospun PVDF fibers can be adjusted at the same time. Through the control of electrospinning parameters such as the solvent, electrospinning temperature, feeding rate, and tip‐to‐collector distance, PVDF fibrous membranes containing mainly α‐ or β‐ or γ‐phase could be fabricated successfully.

     

Fabrication of Light‐Guiding Core/Sheath Fibers by Coaxial Electrospinning

Light‐guiding core/sheath fibers are fabricated from two different refractive index (RI) polymers by coaxial electrospinning. The morphology and fiber diameter are analyzed with scanning electron and fluorescence microscopies. It is found that the diameter of the core and the thickness of the sheath could be varied from 100 to 400 nm by changing the concentration of the outer solution. The incorporation of a chromophore into the inner material confirmed the uniformity of the core/sheath structure in long segments of the fibers. The boundary is clearly seen: the core diameter and the thickness of the sheath are constant along the fiber axis in fluorescence images. The ejected beam is circular and light‐guided along the fiber axis as in an optical fiber.

     

高分子控温相变免疫分析法测定苯妥因

利用水溶性高分子聚合物Ｎ－异丙基丙烯酰胺和抗体的偶联，用异硫氰酸荧光素标记苯妥因作为竞争物建立了免疫测定苯妥因的新方法，与均相方法相比灵敏度有很大提高，其灵敏度达到２５μｇ／Ｌ，测定可在３０ｍｉｎ内完成。这一新方法可望应用于苯妥因的临床检测。     

Poly(L-lactide) Nano- and Microfibers by Electrospinning: Influence of Poly(L-lactide) Molecular Weight

Summary: The electrospinning technique based on single and multi-jet systems was applied for poly(L -lactide) (PLA) nano- and microfibers as well as fibrous mats manufacture; the latter with dimensions suitable for the tensile tests. The PLA's employed were prepared by the controlled ring-opening polymerization of the L,L -lactide (LA) monomer. The resulting fibers thickness was correlated with molecular weights of PLA's and viscosities of spinning solutions. The scanning electron microscopic, thermal, and tensile characteristics of the polymeric materials and fibrous mats were also examined.     

基于低温热释放的烷基接枝相变偶氮苯材料

通过Mills法合成了两种不同取代基的烷基接枝相变偶氮苯——4-正戊基偶氮苯(Azo5)和2′-甲基-4-正戊基偶氮苯(AzoM5). 通过核磁共振氢谱和傅里叶变换红外光谱表征了Azo5和AzoM5的化学结构, 利用紫外-可见光谱、 示差扫描量热仪和红外热像仪分析了材料的异构化性能、 循环稳定性、 储热和放热性能, 并测试了?10 ℃环境下的热量释放能力. 结果表明, Azo5和AzoM5由于分子间作用力低, 呈现出低熔点、 快速异构化的特点, 并且由于低温下的光致相变行为, 能量密度显著提高, 分别达到216和218 J/g. 红外热成像仪观测结果表明, 在可见光照射下, Azo5在低温环境(?10 ℃)下可以实现6 ℃的温度提升.     

Fabrication of CdS Nanorods in PVP Fiber Matrices by Electrospinning

Summary: A controlled fabrication of rod‐like nanostructures of cadmium sulfide (CdS) incorporated into polymer fiber matrices has been developed by an electrospinning method. Here, poly(vinyl pyrrolidone) (PVP) was used as a polymer capping reagent, utilizing the interactions of cadmium ions with the carbonyl groups in the PVP molecules. The formation of CdS nanorods inside the PVP was carried out via the reaction of Cd²⁺ with H₂S. SEM images showed that the electrospun films of PVP/CdS are composed of fibers with a diameter between 100 and 900 nm. TEM proved that most of the CdS nanorods are incorporated in the PVP fibrous film. The diameter of the rod is about 50 nm and the length is from 100 to 300 nm.

TEM image of the CdS nanorods formed in the PVP fibrous film.     

高压静电纺丝法制备P(VDF-HFP)聚合物电解质

以高压静电纺丝法制备了具有微孔结构的偏氟乙烯-六氟丙烯共聚物[P(VDF-HFP)]无纺布膜, 吸附离子液体3-乙基-1-甲基咪唑鎓四氟硼酸盐(EMIBF₄)后成为凝胶聚合物电解质, 其室温离子电导率达到8.43 mS•cm^－1, 初始热失重温度超过300 ℃. 以其为聚合物电解质的活性碳电极双电层电容器具有较好的电化学性能, 1.0 mA•cm^－2恒流充放电500次循环后仍保持 90.67 F•g^－1的比容量, 容量保持率为96.86%.     

Poly(dicyclopentadiene) Submicron Fibers Produced by Electrospinning

Summary: We have used the process of electrospinning to produce fibers of poly(dicyclopentadiene) with diameters on the submicron scale. The material, formed from a monomer‐catalyst solution, polymerized in flight during the electrospinning process. Fibers were collected over trenches etched in silicon and the Young's moduli were measured using an atomic force microscope to measure force‐displacement curves. The resulting values of Young's moduli are larger than typical values for bulk polymer material.

SEM image of suspended PDCPD fiber.     

Synthesis,Characterization, and Photocatalytic Properties of Ag/TiO2 Composite Nanofibers Prepared by Electrospinning

Ag nanoparticles (Ag NPs) embedded titanium dioxide (TiO₂) nanofibers were fabricated by colloidal sol process, electrospinning, and calcination technique. Calcination of the electrospun nanofibers were heat treated at 600°C for 180 minutes in air atmosphere. X-ray diffraction patterns exhibited that the anatase phase and silver coexisted in the resulted Ag NPs/TiO₂ nanofibers; transmission electron microscopy demonstrated Ag NPs well spread in the porous microstructure of composite fibers. The prepared nanofibers were utilized as photocatalyst for degradation of methyl orange. The degradation rate of methyl orange dye solution containing Ag/TiO₂ composite nanofibers is 99% only after irradiation for 3 hours. It is proposed that these new Ag NPs/TiO₂ composite nanofibers will have potential application in water pollution treatment.      

Control over Internal Structure of Liquid Crystal Polymer Nanofibers by Electrospinning

Liquid crystal polymer nanofibers with a diameter ranging from 0.13 to 4.71 µm were prepared by electrospinning from a main‐chain liquid crystalline polyester, BB‐5(3‐Me). WAXD measurements showed that the formation and orientation of the ordered structure in the electrospun fibers were controlled by the fiber diameter formed during electrospinning. For BB‐5(3‐Me), the SmA structure with two layer spacings was formed in the fiber during the electrospinning. Under optimal spinning conditions, the SmA structure is highly oriented in the fiber. In addition, annealing transformed the metastable SmA structure in the BB‐5(3‐Me) fiber into stable SmCA one.

     

微胶囊技术及其在相变材料中的应用

微胶囊技术因其独特的功能而得到广泛的应用。微胶囊相变材料是将微胶囊技术应用到相变材料中而形成的新型复合相变材料。文章介绍了微胶囊技术及其功能,重点论述了微胶囊相变材料及其结构组成、制备方法、研究进展和应用领域,并对其发展前景进行了展望。     

Preparation of Core‐Sheath Composite Nanofibers by Emulsion Electrospinning

Summary: Uniform core‐sheath nanofibers are prepared by electrospinning a water‐in‐oil emulsion in which the aqueous phase consists of a poly(ethylene oxide) (PEO) solution in water and the oily phase is a chloroform solution of an amphiphilic poly(ethylene glycol)‐poly(L ‐lactic acid) (PEG‐PLA) diblock copolymer. The obtained fibers are composed of a PEO core and a PEG‐PLA sheath with a sharp boundary in between. By adjusting the emulsion composition and the emulsification parameters, the overall fiber size and the relative diameters of the core and the sheath can be changed. A mechanism is proposed to explain the process of transformation from the emulsion to the core‐sheath fibers, i.e., the stretching and evaporation induced de‐emulsification. In principle, this process can be applied to other systems to prepare core‐sheath fibers in place of concentric electrospinning and it is especially suitable for fabricating composite nanofibers that contain water‐soluble drugs.

Schematic mechanism for the formation of core‐sheath composite fibers during emulsion electrospinning.     

Polymer Architectures Consisting of Rotating Fibers Prepared by Photopolymerization in a Cholesteric Phase

Summary: Hydrogen‐bonded polymer films consisting of fine, extended fibers were prepared by photopolymerization of an acrylate monomer containing a benzoic acid group in the fingerprint or Grandjean textures of a cholesteric liquid‐crystalline mixture. Scanning electron microscopy and circular dichroism spectroscopy revealed that the fibers, measuring about 400 nm in diameter, formed helical superstructures and that their helical axes corresponded to the cholesteric helical axes that existed in the LC mixture before photopolymerization.

SEM image of a polymer film.     

相变调温微胶囊的制备

采用原位聚合法用三聚氰胺-甲醛树脂包覆正十八烷,制备出相变微胶囊．利用扫描电镜和差示扫描量热仪对微胶囊试样的表面形貌和热物理性能进行了研究．实验结果表明：制备的相变微胶囊表面光滑,平均粒径2．84μm,平均壁厚0．41μm．