静电纺制备纳米孔结构聚乳酸(PLLA)超细纤维

采用静电纺丝法制备了孔径为40～150 nm的PLLA纳米孔结构超细纤维,纳米孔不仅分布在纤维表面,而且存在于纤维内部.通过扫面电镜观察了纤维表面形貌.探讨了混合溶剂二氯甲烷/N,N-二甲基甲酰胺的比例、PLLA浓度、电场强度对PLLA纤维纳米孔大小、分布密度、深度的影响.结果表明通过调节PLLA溶液性质和纺丝参数,PLLA纤维的表面形貌可以在3种状态即光滑无孔、疏浅凹坑、密集深孔之间可控.二氯甲烷/N,N-二甲基甲酰胺比例为1∶4,PLLA浓度9%,电场强度1 kV/cm,环境温湿度分别为30℃和52%,静电纺丝所得PLLA超细纤维表面孔洞直径为150 nm,孔洞分布密集.纳米孔PLLA纤维形成的主要机理是由于静电纺丝过程中溶剂的快速挥发引起纤维表面温度急剧降低导致热致相分离而产生多孔结构.PLLA纤维膜的疏水性与纤维表面孔洞结构密切相关,纤维膜接触角最高可达146.6°.由于PLLA纤维的多孔结构,这种高疏水性的PLLA纤维膜能够快速、大量地吸油,90 s内吸收柴油达到90 g/g,25 min内可以达到145 g/g.     

酸碱度对金纳米结构形貌的调控及其机理研究

本文通过调节环境pH酸碱度改变聚电解质膜中氨基基团的键合状态,以控制聚电解质膜表面金纳米粒子的原位还原与自组装过程中的聚集行为,发现当聚电解质膜经pH为5.40的去离子水处理后可在其表面制备出片状金纳米结构;经pH为0.65的强酸溶液处理后,可在膜表面制备出树枝状的金纳米结构,且尺寸比pH为5.40条件下增大一倍;经pH为12.77的强碱溶液处理后,金纳米粒子的聚集状态发生改变,形成了球形纳米结构;对金纳米粒子形貌的调控机理进行了初步探讨.     

冷冻干燥法制备天然高分子复合聚电解质纳米纤维

将壳聚糖(CS)溶液和透明质酸钠(SH)溶液共混,制备成CS-SH复合聚电解质溶液,并对溶液中所形成的胶粒进行了粒径分布和ZETA电位表征。用冷冻干燥法除去溶剂,制备了CS-SH复合聚电解质纳米纤维膜。用FT-IR对其结构进行分析,并用SEM对其形貌进行了表征。并将复合聚电解质纳米纤维膜作为疏水性药物紫杉醇(PTX)的载药体系,研究了其药物释放行为。结果表明,PTX在该载体中的释放较为平缓,这可以延长药物的有效时间,降低给药次数,增强治疗效果,降低药物的毒副作用。     

γ-Al2O3柔性纳米纤维膜的制备及机械性能

以氯化铝和异丙醇铝为原料, 水和乙醇为溶剂, 通过溶胶凝胶结合静电纺丝法制备了柔性γ-Al2O3纳米纤维膜.表征了纤维膜的形貌和机械性质, 并研究了纤维膜的形成过程.组成纤维膜的纤维直径均匀, 平均直径188 nm, 纤维由粒径在15~30 nm的纳米颗粒组成且表面光滑.制备的纤维膜具有较好的柔性及抗拉强度(1.01 MPa).     

离子液体/聚偏氟乙烯纳米纤维的防结冰性能（英文）

通过静电纺丝方法制备了掺杂离子液体([BMIM][PF_6])的聚偏氟乙烯(PVDF)纳米纤维.研究结果表明,[BMIM][PF_6]与PVDF具有相互作用,并可促进PVDF形成β相晶体.在溶剂挥发后,离子液体存在于PVDF纳米纤维的表面.纳米纤维中的离子液体含量对复合纳米纤维的表面形态和润湿性具有显著影响.通过离子液体的引入,可有效推迟水滴在纳米纤维表面的结冰时间,降低水滴的结晶温度,并且降低冰黏附强度.研究结果显示含有10%[BMIM][PF_6]的PVDF纳米纤维疏水性最高,并具有优异的防结冰性质.     

γ-Al_2O_3柔性纳米纤维膜的制备及机械性能（英文）

以氯化铝和异丙醇铝为原料,水和乙醇为溶剂,通过溶胶凝胶结合静电纺丝法制备了柔性γ-Al_2O_3纳米纤维膜.表征了纤维膜的形貌和机械性质,并研究了纤维膜的形成过程.组成纤维膜的纤维直径均匀,平均直径188 nm,纤维由粒径在15~30 nm的纳米颗粒组成且表面光滑.制备的纤维膜具有较好的柔性及抗拉强度(1.01 MPa).     

离子液体/聚偏氟乙烯纳米纤维的防结冰性能

通过静电纺丝方法制备了掺杂离子液体([BMIM][PF₆])的聚偏氟乙烯(PVDF)纳米纤维. 研究结果表明, [BMIM][PF₆]与PVDF具有相互作用, 并可促进PVDF形成β相晶体. 在溶剂挥发后, 离子液体存在于PVDF纳米纤维的表面. 纳米纤维中的离子液体含量对复合纳米纤维的表面形态和润湿性具有显著影响. 通过离子液体的引入, 可有效推迟水滴在纳米纤维表面的结冰时间, 降低水滴的结晶温度, 并且降低冰黏附强度. 研究结果显示含有10%[BMIM][PF₆]的PVDF纳米纤维疏水性最高, 并具有优异的防结冰性质.     

基于液体弹珠原位制备载水胶囊及其性能

首先以疏水性二氧化硅微粒为稳定剂,通过包覆水滴制备了液体弹珠;然后在其表面滴涂α-氰基丙烯酸乙酯,通过湿气固化制得聚合物涂层封装的液体弹珠;最后在弹珠表面进一步涂覆环氧大豆油丙烯酸酯涂层,通过紫外光固化制得载水胶囊。采用数码照片、超景深显微镜、扫描电子显微镜对液体弹珠及载水胶囊的形貌进行了表征;采用实时傅里叶红外光谱研究了光固化涂层的双键转化率,探讨了涂层的硬度、耐水性等基本性质;并研究了载水胶囊的力学强度及保水性能。结果表明:相较于原始液体弹珠,所制备的载水胶囊表面光滑且致密;由聚α-氰基丙烯酸乙酯涂层和环氧大豆油丙烯酸酯光固化涂层组成的壁材赋予了载水胶囊良好的水汽阻隔性能和力学性能。     

基于聚丙烯酰胺凝胶软印章的电化学纳米加工(英文)

电化学刻蚀使用腐蚀性小的电解质溶液,且溶液可使用周期长,是一种环境友好的加工工艺.本文采用聚丙烯酰胺水凝胶(PAG)作为软印章,辅以优化工艺,将电化学湿印章技术(E-WETS)的加工精度从几十微米提高到了200纳米.将新配制的聚丙烯酰胺水凝胶浇注在具有纳米结构的软模板表面,固化后脱模并保存于0.2mol·L-1KCl溶液中,在合适电位和压力下,对硅片表面金膜进行电化学湿法刻蚀,分别研究了聚丙烯酰胺水凝胶的聚合条件、电化学加工电位以及水凝胶表面压力对加工结果的影响.实验表明,在最优条件下可加工出直径为200纳米的特征点阵结构,且该方法具有较好的可靠性和稳定性。     

静电纺丝制备具有浸润性梯度的聚酰亚胺纳米纤维膜

采用高压静电纺丝技术, 在非对称异型电极上制备得到放射状聚酰亚胺(PI)纳米纤维膜. 采用环境扫描电子显微镜(ESEM)观察了PI膜的微观形貌以及纳米纤维的排列状态; 采用接触角测量仪研究了水滴浸润性的变化; 采用高敏感性力学微电力学天平测量了水滴的黏附力, 分析了微观形貌变化与水滴浸润性质和黏附性质的关系. 结果表明, 该PI纳米纤维膜沿着非对称异型电极三角电极至弧型电极方向纤维排列由密到疏, 呈放射状, 具有独特的微结构梯度; 整个纤维膜上的PI纳米纤维直径均一且具有光滑均匀表面, 纤维与纤维之间的距离约为几微米到几十微米. 由于PI纳米纤维膜所具有的独特的微结构梯度, 致使沿着微结构梯度方向水滴的接触角(从超疏水到疏水)和黏附力(从低黏附到高黏附)均表现出梯度变化的特征.     

Mechanical reinforcement and water repellency induced to cellulose sheets by a polymer treatment

The present study reports a simple method to control the mechanical and surface properties of cellulose fiber networks and to protect them from humidity, without altering their initial morphology. This is achieved by dip coating the fiber networks in solutions containing different amounts of ethyl cyanoacrylate monomer (ECA). Under ambient humidity and due to the presence of the -OH groups of the cellulose, the ECA polymerizes around each individual cellulosic fiber forming a thin poly(ethyl cyanoacrylate) (PECA) shell. PECA was found to interact with the cellulose surface via hydrogen bonding as evidenced by Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. The detailed surface characterization reveals that only 3.5 wt% of ECA in solution is sufficient to form compact PECA cladding around every cellulose fiber. After the proposed treatment the cellulose sheets become hydrophobic, well protected from the environmental humidity and with increased Young’s modulus.     

Programmed hyperhelical supramolecular assembly of nickel phthalocyanine bearing enantiopure 1-(p-tolyl)ethylaminocarbonyl groups

The present paper reports uniqueness of a simple, programmed design of disk-shaped homochiral nickel phthalocyanine (Pc) molecules bearing four enantiomerically pure 1-(p-tolyl)ethylaminocarbonyl groups at their peripheral positions, (Pc-(R) and Pc-(S)), and their controlled self-organization into mesoscopic supramolecular helical fibers with a preferential handedness in solution and onto solid surfaces. A combination of four fundamental intermolecular interactions, including quadruple hydrogen bonding, pi-pi stacking, homochiral interactions of the enantiopure bulky aralkyl entities, and noncoordinating nature of nickel ion of the Pc molecules afforded a high thermal stability of the Pc self-assembly in chloroform (CHCl(3)), tetrahydrofuran, and o-dichlorobenzene and onto hydrophilic mica and hydrophobic HOPG surfaces. A higher-ordered helical self-assembly of Pc disks was observed in these solutions (approximately 200 Pc molecules), while the self-assembly was completely dissociated into monomeric species in N,N-dimethylformamide due to a loss of hydrogen-bonding interactions between Pc molecules. Supramolecular chirality in the hierarchical self-assembly of Pc molecules originated from the presence of (R)- or (S)-chiral centers in the peripheral tails, which rotate noncovalently linked molecular building blocks to effectively form the helical architectures. The helical Pc nanofibers dissolved in CHCl(3), estimated to be ca. 70 nm from peak molecular weight obtained by SEC analysis, acts as a building block for higher-order helical fibers (ca. 1 microm) at single molecular level on the solid surfaces, as demonstrated by the dynamic force mode atomic force microscopy. Regardless of hydrophilic and hydrophobic substrates, the interaction between these Pc molecules and the solid surfaces could not affect the morphology of helical assemblies, indicating a unique robustness of these assemblies.     

Preparation of porous ultrafine polyacrylonitrile (PAN) fibers by electrospinning

A facile method for the preparation of porous ultrafine nanofibers was demonstrated. The PAN/NaHCO₃ composite nanofibers were electrospun, and then NaHCO₃ was removed by a selective dissolution and reaction with the solution of hydrochloric acid (10 wt%). The obtained PAN fibers showed highly porous surfaces after the extraction of NaHCO₃. The structure and properties of ultrafine PAN nanofibers were characterized by Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and thermogravimetry (TG). The results indicated that NaHCO₃ could be introduced into the PAN solution and successfully electrospun. CO₂ is released and pores are formed on the fibers. The morphology image of the fibers was detected by scanning electron microscope (SEM) and showed that many pores aligned the nanofibers. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation of cellulose nanofibers with hydrophobic surface characteristics

The aim of this study was to develop cellulose nanofibers with hydrophobic surface characteristics using chemical modification. Kenaf fibers were modified using acetic anhydride and cellulose nanofibers were isolated from the acetylated kenaf using mechanical isolation methods. Fourier transform infrared spectroscopy (FTIR) indicated acetylation of the hydroxyl groups of cellulose. The study of the dispersion demonstrated that acetylated cellulose nanofibers formed stable, well-dispersed suspensions in both acetone and ethanol. The contact angle measurements showed that the surface characteristics of nanofibers were changed from hydrophilic to more hydrophobic when acetylated. The microscopy study showed that the acetylation caused a swelling of the kenaf fiber cell wall and that the diameters of isolated nanofibers were between 5 and 50 nm. X-ray analysis showed that the acetylation process reduced the crystallinity of the fibers, whereas mechanical isolation increased it. The method used provides a novel processing route for producing cellulose nanofibers with hydrophobic surfaces.     

超疏水导电聚苯胺的界面聚合

采用界面聚合和无模板法相结合的方法, 以具有疏水链的全氟癸二酸(PFSEA)为掺杂剂, 通过调节苯胺单体和FeCl₃氧化剂的浓度实现了聚苯胺三维微/纳米结构形貌和尺寸的可控制备. 扫描电子显微镜测量结果显示, 聚苯胺是由一维纳米纤维自组装形成的三维微球结构; 红外吸收光谱和紫外-可见吸收光谱结果表明, 聚苯胺微球为掺杂态. 室温下, 该微/纳米结构聚苯胺微球的电导率为 9.6×10^-3 S/cm, 表面水接触角为161.4°, 表现出半导体特性和超疏水性.     

Electrospinning Process of Thermo-sensitive Poly(N-isopropylacrylamide) /poly (2-acrylamido-2-methylpropanesulfonic acid) Nanofibers

Poly (N-isopropylacrylamide)/poly (2-acrylamido-2-methylpropanesulfonic acid) (PNIPAAm/PAMPS) nanofibers was prepared using the electrospinning technique. The electrospinning process parameters such as solution concentration, voltage, receiver distance and flow rate were determined by the orthogonal experiments. The appropriate electrospinning parameters were 7.0% of solution concentration, 10.0 kV of voltage, 20 cm of distance and 3.1 μL·min^?1 of flow rate, respectively. The major factor affecting the nanofibers diameter was the solution concentration and the diameter increased with the solution concentration. The Fourier-transform infrared spectroscopy (FTIR) was conducted to characterize the structure of the components for electrospinning. Scanning electron microscopy (SEM) was taken to observe the morphology, and the contact angle (CA) measuring was carried out to determine the wettability of the nanofibers with temperatures. The results of SEM observation showed that the surfaces of nanofibers were smooth with uniform fibrous diameters and without the formation of beads. The CA detections showed that the electrospun PNIPAAm/PAMPS nanofibers exhibited thermo-sensitivity of hydrophilicity at 20°C and hydrophobicity at 40°C.     

晶相可控的ZrO2纳米线的无卤制备及表征

采用无卤法制备晶相可控的ZrO₂纳米线. 通过静电纺丝法制备聚乙烯吡咯烷酮(PVP)与Zr(NO₃)₄的复合纤维; 再通过煅烧法在除去聚合物模板的同时制备ZrO₂纳米线. 采用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 傅里叶变换红外光谱(FTIR)仪及热重差热联用热分析仪(DSC-TGA)对材料的晶相结构、 形貌及热稳定性进行表征. 通过改变煅烧温度, 可以实现ZrO₂纳米材料形貌及晶相组成的调控.     

Electrochemical modification of surface morphology of Au/Ti bilayer films deposited on a Si prism for in situ surface-enhanced infrared absorption (SEIRA) spectroscopy

Surface-enhanced infrared absorption (SEIRA)-active Au/Ti bilayer films sputter deposited on Si substrates have been prepared by an electrochemical annealing (ECA) treatment for the first time. The application of Au/Ti bilayer films on Si substrates to the spectroscopic technique is a promising alternative to the conventional technique using directly deposited Au films on Si substrates, offering excellent adhesive durability of the deposited metal films. However, Au/Ti bilayer films have never been selected for the spectroscopy technique because the films in the as-prepared state exhibit relatively smooth surface morphology: the excitation of the localized surface plasmon is vital to achieving SEIRA enhancements but could hardly be observed on the smooth morphology. It is shown by ex situ scanning tunneling microscopy measurements that the unfavorable smooth morphology of the as-prepared Au/Ti bilayer films can be modified by the ECA treatment to a reasonably rough, island-structure morphology similar to that of the conventional SEIRA-active Au films. In situ infrared absorption spectroscopy of adsorbed sulfate anions has been conducted on the Au/Ti bilayer film both before and after ECA treatment. The spectroscopy measurements demonstrate that the SEIRA activity of the film after being subjected to the treatment is significantly improved so that the technique could detect adsorbates on the film electrodes even with the submonolayer coverage. As an additional benefit, the ECA treatment has brought about a substantial increase in the fraction of Au(111) domains on the polycrystalline Au film surfaces. Accordingly, this approach enables us to prepare SEIRA-active Au films having sufficient adhesion to the Si substrates as well as the highly preferred (111) orientation.     

Pentadecyl phenol- and cardanol-functionalized fluorescent, room-temperature liquid-crystalline perylene bisimides: effect of pendant chain unsaturation on self-assembly

A new perylene bisimide (PBI) building block based on pentadecyl phenol (PDP) or cardanol was developed, which upon esterification with 3,4,5-tridodecyloxy gallate resulted in highly emissive, room-temperature liquid-crystalline (LC) molecules. The self assembly in solution was studied in detail by NMR spectroscopy, UV/Vis absorption, and fluorescence spectroscopy. In solution both PDP- and cardanol-based PBI exhibited similar behavior. They were molecularly dissolved in chloroform (CHCl(3)) but formed rotationally displaced H-type aggregates that emitted at 640 nm in methylcyclohexane (MCH). Surface morphology in dropcast films were characterized using microscopic techniques such as SEM, TEM, and atomic force microscopy (AFM). The liquid-crystalline properties were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and variable-temperature X-ray (small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WXRD)) studies. Variable-temperature X-ray studies in the LC phase indicated strong π-π stacking interaction present in the PDP-based PBI derivative, whereas the stacking was absent in the LC phase of the cardanol-based PBI. The latter formed self-organized structures of extremely short length due to the presence of cis double bonds in the C15 alkyl side chain, whereas the saturated alkyl side chain in PDP could pack efficiently, thereby resulting in nanofibers that were several micrometers in length.     

Functionalized graphene oxide-reinforced electrospun carbon nanofibers as ultrathin supercapacitor electrode

Graphene oxide has been used widely as a starting precursor for applications that cater to the needs of tunable graphene. However, the hydrophilic characteristic limits their application, especially in a hydrophobic condition. Herein, a novel non-covalent surface modification approach towards graphene oxide was conducted via a UV-induced photo-polymerization technique that involves two major routes; a UV-sensitive initiator embedded via pi-pi interactions on the graphene planar rings, and the polymerization of hydrophobic polymeric chains along the surface. The functionalized graphene oxide successfully achieved the desired hydrophobicity as it displayed the characteristic of being readily dissolved in organic solvent. Upon its addition into a polymeric solution and subjected to an electrospinning process,non-woven random nanofibers embedded with graphene oxide sheets were obtained. The prepared polymeric nanofibers were subjected to two-step thermal treatments that eventually converted the polymeric chains into a carbon-rich conductive structure. A unique morphology was observed upon the addition of the functionalized graphene oxide, whereby the sheets were embedded and intercalated within the carbon nanofibers and formed a continuous structure. This reinforcement effectively enhanced the electrochemical performance of the carbon nanofibers by recording a specific capacitance of up to 140.10 F/g at the current density of 1 A/g, which was approximately three folds more than that of pristine nanofibers.It also retained the capacitance up to 96.2% after 1000 vigorous charge/discharge cycles. This functionalization technique opens up a new pathway in tuning the solubility nature of graphene oxide towards the synthesis of a graphene oxide-reinforced polymeric structure.