PVA微晶交联和SA/PAA双网络协效增强增韧SA纤维

为了提高海藻酸钠(SA)纤维的断裂强度和断裂伸长率, 以丙烯酸(AA)为化学交联组分, SA为离子交联组分, 聚乙烯醇(PVA)为微晶交联组分, 采用湿法纺丝和冻融循环方法制备含有PVA微晶交联点和海藻酸钠/聚丙烯酸(SA/PAA)双网络结构的海藻酸钠/聚丙烯酸/聚乙烯醇(SA/PAA/PVA)复合纤维. 通过流变性能、 力学性能、 红外光谱、 X射线衍射仪(XRD)和扫描电子显微镜(SEM)测试研究了交联剂N,N-亚甲基双丙烯酰胺(MBA)含量和PVA微晶交联对SA/PAA/PVA纺丝原液和复合纤维的结构与性能的影响. 结果表明, 当MBA质量分数为0.5%时, 纺丝原液的损耗模量(G″)最小, 可纺性最好, 复合纤维的断裂强度达到2.83 cN/dtex, 断裂伸长率达到9.38%, 比再生SA纤维分别提高了15.98%和38.96%; PVA冷冻之后形成微晶交联点并且PAA和PVA已经复合到体系中; PAA和PVA的加入提高了复合纤维的结晶度; 复合纤维的表面形貌趋于光滑和规整, 纤维断面更加致密.     

金纳米棒负载的静电纺丝纤维的制备及其表面增强拉曼光谱性能

为简单有效地制备高活性表面增强拉曼光谱(Surface-enhanced Raman Spectroscopy,SERS)基底。本文采用静电纺丝聚乙烯醇(PVA)/聚丙烯酸(PAA)纳米纤维为支撑材料,通过直接浸泡的方法,利用金纳米棒与电纺纤维之间的静电力,使纳米棒在纤维表面自组装,得到了性能优异的SERS基底。通过透射电子显微镜、扫描电子显微镜对金纳米棒以及不同状态下的电纺纤维的形貌进行表征,结果表明,金纳米棒均匀且密集地负载在纤维表面。通过设置不同的浸泡时间确定了金纳米棒组装平衡的时间为12 h,并通过调控纺丝时间和金纳米棒的浓度发现随着纺丝时间和金纳米棒浓度的增加,复合纤维膜SERS增强效果随之提升。该复合纤维膜具有优异的SERS均匀性,并且能够检测到浓度低至10~(-10)mol/L的4-氨基苯硫酚的存在。     

钯/聚乙烯醇纤维膜催化水相中的Heck偶联反应

通过静电纺丝和热交联技术、以聚乙烯醇( PVA)作为载体制备了一种电纺纤维膜负载型钯催化剂.利用扫描电镜(SEM)、能谱仪(EDS)和X射线光电子能谱(XPS)对其进行了表征.SEM结果显示:PdCl2的加入导致PVA纤维直径增加、形貌变差,而热交联过程可以减小纤维直径、改善纤维形貌.XPS表征则表明PVA可以还原pd...     

大豆分离蛋白/聚乙烯醇的电纺研究

对大豆分离蛋白(SPI)/聚乙烯醇(PVA)的电纺进行了研究, 讨论了溶液性质和甘油的加入对SPI/PVA电纺纤维形貌的影响, 并对SPI/PVA电纺膜进行了成分分析和力学性能表征. 结果表明, 加入甘油可以提高SPI/PVA的可电纺性, 同时使SPI/PVA电纺膜的拉伸强度从不含甘油的(5.17±0.62) MPa下降到含有甘油的(1.67±0.21) MPa, 而伸长率呈增加趋势.     

氨基官能化聚乳酸电纺纤维的制备、 表征和应用

通过聚乳酸(PLA)和氨基丙基三乙氧基硅烷(KH550)混合进行静电纺丝制备氨基官能化聚乳酸纳米纤维. 采用滴定法测定了纤维表面氨基含量, 证明当KH550的添加量为3%~13%(质量分数)时, 有19%~26%的氨基出现在纤维的表面. 利用场发射扫描电子显微镜、 差示扫描量热(DSC)仪、 接触角测试仪和电子拉伸机对纤维形貌、 PLA的玻璃化转变温度和熔点以及纤维膜的亲水性和力学性能进行了表征. 结果表明, KH550的加入可以在电纺纤维表面引入氨基, 同时使纤维直径变细, 使PLA的玻璃化转变温度上升, 熔点下降, 电纺纤维膜的亲水性略有增加, 力学性能有所下降. 通过吸附将金纳米粒子负载到氨基官能化聚乳酸电纺纤维膜上, 得到负载型催化剂, 对硼氢化钠还原对硝基苯酚的反应具有良好的催化活性和重复使用性.     

溶剂性质对两亲性聚肽静电纺丝的影响

通过对聚(γ-苄基L-谷氨酸酯)(PBLG)的亲水改性制备了两亲性聚(γ-苄基L-谷氨酸酯-co-羟乙谷酰胺)无规共聚肽(PBHG)用于静电纺丝制备超细纤维.通过傅里叶变换红外光谱、核磁共振氢谱表征了聚合物结构.通过测定溶液表面张力、黏度、电导率及扫描电镜观察纤维形貌考察了不同溶剂及PBHG浓度对纺丝溶液性质及电纺纤维的影响.通过水浸实验及MTT法评价了电纺纤维膜的亲水性及细胞相容性.研究发现在三氯甲烷(TCM)和四氢呋喃(THF)中PBHG采取α-螺旋构象,刚性分子链自取向排列,可获得直径为微米或亚微米的电纺纤维.以TCM为溶剂时,因溶液表面张力大、导电率低导致纤维品质较差,而以THF为溶剂可获得表面光洁、尺寸均匀的电纺纤维.当溶剂为三氟乙酸(TFA)时,PBHG采取无规线团构象,柔性分子链彼此缠结,同时溶液表面张力小、黏度低、电导率高,可获得纳米电纺纤维.但因TFA挥发性相对较差,易造成纤维粘连.将TFA与TCM复配后作为溶剂可改善纤维粘连问题.与PBLG电纺纤维相比,改性后的PBHG电纺纤维的亲水性得到了改善,可在水中保持纤维骨架而无需交联,并表现出良好的细胞相容性,能促进细胞在电纺纤维膜上的增殖.     

同轴电纺制备刚性多糖纳米纤维膜

将壳聚糖、海藻酸钠或透明质酸配制成水溶液,聚氧化乙烯(PEO)溶解在二甲基甲酰胺(DMF)/H2O 混合溶剂中,以上述两溶液分别作为内、外纺丝液进行同轴电纺制备成纤维膜,进而利用适当溶剂除去 PEO 外壳,得到纯多糖纳米纤维膜.纤维结构通过 TEM、SEM 进行表征.结果表明:同轴电纺可一步制得外壳为 PEO、内核为刚性多糖的核壳纳米纤维,纤维外壳 PEO 组分可以用氯仿萃取除去;与单轴电纺法制得的刚性多糖纤维相比,同轴电纺可以保持最终纤维的结构完整性.     

抗污染PVA/PVDF电纺纳米纤维复合超滤膜的制备及过滤性能

以聚对苯二甲酸二醇酯(PET)无纺布为基底,聚偏氟乙烯(PVDF)纳米纤维为支撑层,聚乙烯醇(PVA)纳米纤维膜为分离层,采用静电纺丝法制备超滤膜,并用水/丙酮混合溶液对复合纳米纤维膜表面进行溶液处理,再加入戊二醛交联改性得到致密分离层.采用扫描电子显微镜(SEM)和红外光谱(FTIR)表征了复合超滤膜的表面,用水接触角(WCA)表征复合超滤膜的亲水性.在0.02 MPa恒压下死端过滤油/水乳液,测试复合超滤膜的过滤性能.结果表明,最优条件下制备的复合超滤膜死端过滤油/水乳液的通量为(42.50±4.78)L/(m~2·h),截留率达到(95.72±0.33)%;循环使用5次后,依然具有较好的过滤性能,常压下死端过滤复合超滤膜的纯水通量为(3469±28)L/(m~2·h).     

PVA/GA/β-CD纳米纤维的制备及染料吸附性能

利用静电纺丝技术,以六氟异丙醇(HFIP)和水为溶剂,制备了环糊精(β-CD)含量为70%(质量分数)的聚乙烯醇(PVA)/β-CD纳米纤维,并经戊二醛(GA)交联处理得到了可用于染料吸附的PVA/GA/β-CD纳米纤维.通过红外光谱和扫描电子显微镜研究了交联反应前后纳米纤维组成和形貌的变化;考察了PVA/GA/β-CD纳米纤维对7种水溶性染料的吸附性能.结果表明,PVA/GA/β-CD纳米纤维对孔雀石绿、甲基紫和刚果红的吸附效果较好,最大吸附量分别为124.71,121.14和127.39 mg/g,4次吸附-解吸附循环后,染料去除率仍保持80%左右,在染料废水处理中具有良好的应用前景.     

聚乙烯醇明胶混合水溶液的静电纺丝

将聚乙烯醇与明胶混合水溶液进行静电纺丝,制备了聚乙烯醇与明胶混合超细纤维及其电纺膜,研究了混合纺丝液的组成对纺丝液的粘度、表面张力和电导率的影响,观察了纤维的微观形貌,并对电纺膜进行了差示扫描量热测定.结果表明:当混合液中明胶含量小于20 9/6时,静电纺丝可以稳定进行.随着明胶含量由5%逐渐增加至25%,混合超细纤维的平均直径先是由260nm逐渐下降至207 nm而后又逐渐增加至320 nm.明胶的含量低于15%时,不影响其混合电纺膜中PVA的结晶.     

Study on morphology of electrospun poly(vinyl alcohol) mats

Submicron poly(vinyl alcohol) (PVA) fiber mats were prepared by electrospinning of aqueous PVA solutions in 6-8% concentration. Fiber morphology was observed under a scanning electron microscope and effects of instrument parameters including electric voltage, tip-target distance, flow rate and solution parameters such as concentration on the morphology of electrospun PVA fibers were evaluated. Results showed that, when PVA with higher degree of hydrolysis (DH) of 98% was used, tip-target distance exhibited no significant effect on the fiber morphology, however the morphological structure can be slightly changed by changing the solution flow rate. At high voltages above 10 kV, electrospun PVA fibers exhibited a broad diameter distribution. With increasing solution concentration, the morphology was changed from beaded fiber to uniform fiber and the average fiber diameter could be increased from 87 ± 14 nm to 246 ± 50 nm. It was also found that additions of sodium chloride and ethanol had significant effects on the fiber diameter and the morphology of electrospun PVA fibers because of the different solution conductivity, surface tension and viscosity. When the DH value of PVA was increased from 80% to 99%, the morphology electrospun PVA fibers was changed from ribbon-like fibers to uniform fibers and then to beaded fibers. The addition of aspirin and bovine serum albumin also resulted in the appearance of beads.     

Carbendazim‐loaded electrospun poly(vinyl alcohol) fiber mats and release characteristics of carbendazim therefrom

Ultra‐fine poly(vinyl alcohol) (PVA) electrospun fiber mats containing carbendazim were successfully fabricated by electrospinning from the neat PVA solution containing carbendazim in various amounts based on the weight of PVA. The morphological appearance of both the neat and the carbendazim‐loaded electrospun PVA fibers were smooth and the incorporation of carbendazim in the neat PVA solution did not affect the morphology of the resulting fibers. The average diameters of the neat and the carbendazim‐loaded electrospun PVA fibers ranged between 155 and 160 nm. The chemical integrity of the as‐loaded carbendazim in the carbendazim‐loaded electrospun PVA fiber mats was intact as verified by the ¹H‐nuclear magnetic resonance spectroscopy. Thermal properties of the carbendazim‐loaded electrospun PVA fiber mats were analyzed by differential scanning calorimetry and thermogravimetric analysis. The release characteristics of the carbendazim‐loaded electrospun PVA mats were investigated by the total immersion method in distilled water at 30°C. The carbendazim‐loaded electrospun PVA mats exhibited greater amount of carbendazim released than the carbendazim‐loaded as‐cast films. Copyright © 2010 John Wiley & Sons, Ltd.     

Fabrication,characterization and in vivo evaluation of dexpanthenol sustained-release nanofibers for wound healing

In this study, wound dressings consisting of dexpanthenol (Dex)-loaded electrospun nanofibers were fabricated using polyvinyl alcohol (PVA)/sodium alginate (SA), and chitosan as the core and the shell, respectively. Considering the remarkable properties of chitosan, it was used as a shell against drug release and to improve the thermal stability, and tensile strength of the scaffold. By comparing the thermogravimetric, and tensile strength results of nanofibers with and without shell, it was revealed that the presence of chitosan in the shell side could improve the thermal stability and increased the tensile strength by about three times. The isotherm models of dexpanthenol release from the PVA/SA/Dex-CS scaffold was best described by the Langmuir model. Besides, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction techniques were performed to characterize nanofibers. Furthermore, an in vivo investigation of a wound dressing with dexpanthenol showed better healing compared to the wound dressings without dexpanthenol.     

Preparation of biocompatible system based on electrospun CMC/PVA nanofibers as controlled release carrier of diclofenac sodium

Nanofibers of naturally modified polymer such as carboxymethyl cellulose (CMC) blended with poly(vinyl alcohol) (PVA) at different ratios was obtained by electrospinning technique. The blended solutions of CMC and PVA loaded with and without diclofenac sodium (DS) were electrospun using environmentally benign electrospinning technique in the absence of organic solvents. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) were used to investigate the surface morphology functional groups, as well as the thermal stability of DS loaded CMC/PVA nanofibers mat. The mechanical properties of the as prepared electrospun nanofibers was also evaluated. The entrapment efficiency and the in vitro release of DS loaded CMC/PVA nanofibers were characterized using UV-Vis spectroscopy. The obtained results displayed that the blended nanofibers have shown a smooth morphology, no beads formation when the concentration of CMC was equal or below 5% and beads formation above 5%. FTIR data demonstrated that there were good interactions between CMC and PVA possibly via the formation of hydrogen bonds. The electrospun blended CMC/PVA nanofibers exhibit good mechanical properties. From the in vitro release data, it was found that with the presence of CMC, the release of DS from the nanofibers mats became sustained controlled. Due to the biocompatibility and low cost of the two blended polymers (CMC and PVA), the blended nanofibers system can be considered as one of the promising materials for the preparation of excellent drug carrier.     

Evaluation and correlation of electrochemical and mechanical properties of PVA/SA nanofibres

The present study evaluates and correlates the morphology of poly (vinyl alcohol) (PVA) and sodium alginate (SA) nanofibres with their internal structure to determine dielectric and tensile properties for future applications as long-lasting and resistant cell scaffolds. This work generates electrospun nanofibres mixing SA concentration in a PVA solution cross-linked in calcium chloride media. The dielectric properties of the nanofibres that were obtained using electrochemical impedance spectroscopy (EIS) show that at higher amount of SA in the PVA/SA fibres, the cross-linking process occurs at shorter times, indicating the modification of the internal structure of the PVA/SA. The X-ray photoelectron spectra (XPS) demonstrate that the chemical composition of the nanofibres varies depending on the depth profile. The transmission electron microscopy (TEM) proves that the PVA/SA is formed as a core-shell coaxial nanofibre. The tensile testing demonstrates that with a higher SA concentration, the mechanical properties show brittleness.     

In vitro degradation and release profiles for electrospun polymeric fibers containing paracetanol

In the paper, the poly(D,L-lactide) (PDLLA) and poly(ethylene glycol)-co-poly(D,L-lactide) (PELA) fibers with and without paracetanol drug loading were prepared with an electrospinning method. The morphology of the fibers was observed by scanning electronic microscope (SEM). Their glass transition temperatures (T(g)) were measured with differential scanning calorimetry (DSC). The water contact angle (CA) measurement was also performed to characterize surface properties of fibers. At 37 degrees C in a PBS buffer solution (pH 7.4), in vitro matrix degradation profiles of these fibers were characterized by measuring their weight loss, the molecular weight decrease, and their morphology change. The result showed that the effects of fiber diameter and porosities on the degradation of the electrospun scaffolds might exceed the effects of the molecular weight and the PEG contents, which was different from the polymeric microspheres degradation. In vitro paracetanol release profiles were also investigated in the same condition. The result showed that the drug burst release behaviour was mainly related with the drug-polymer compatibility and the followed sustained release phase depended on polymer degradation.     

电纺聚乙烯醇超细纤维膜的性能研究

由电纺制备聚乙烯醇(PVA)超细纤维膜,以扫描电镜观察纤维的微观形貌,用X射线衍射研究超细纤维膜的结晶行为,并测定了PVA超细纤维膜的力学性能和吸水性.结果表明,PVA超细纤维的平均直径为(184±26)nm,超细纤维中PVA的结晶度和晶体有序程度较浇铸膜低.超细纤维膜的拉伸强度、模量和断裂伸长率均较浇铸膜差,吸水率在300%以上,高于浇铸膜.     

Stabilization of electrospun poly(vinyl alcohol) nanofibrous mats in aqueous solutions

<正>The stability ofpoly(vinyl alcohol)(PVA) nanofibrous mats in water media was improved by post-electrospinning treatments.Bifunctional glutaraldehyde(GA) in methanol was used as a crosslinking agent to stabilize PVA nanofiber,but fiber twinning was observed frequently,and the highly porous structure of PVA nanofibrous mats was destroyed when the crosslinked fiber was soaked in water.To overcome this shortcoming,chitosan(CS) was introduced into the PVA spinning solution to prepare PVA/CS composite nanofibers.Their treatment in GA/methanol solution could retain the fiber morphology of PVA/CS nanofibers and porous structure of PVA/CS nanofibrous mats even if they were soaked in aqueous solutions for 1 month.Scanning electron microscopy(SEM),X-ray diffraction(XRD),thermal gravimetric analysis(TGA) and differential scanning calorimetry(DSC) were applied to characterize the physicochemical structure and thermal properties of PVA nanofibers.It was found that the water resistance of PVA nanofibrous mats was enhanced because of the improvement of the degree of crosslinking and crystallinity in the electrospun PVA fibers after soaking in GA/methanol solution.     

Novel mucoadhesive carriers based on alginate-acrylamide hydrogels for drug delivery

New mucoadhesive two-component carriers for drug delivery based on synthetic acrylamide/diethylacrylamide and natural alginate hydrogels have been synthesized. The introduction of sodium alginate into polyacrylamide/ poly(diethylacrylamide) gels, followed by their crosslinking with metal ions, significantly changed structure and properties of hydrogels, such as swelling degree, drug capacity and drug release rate in physiological solution. The structure of the gels was characterized by FTIR spectroscopy and scanning electron microscopy.