玉米蛋白纳米纤维的制备及其交联研究

用静电纺丝技术制备了玉米醇溶蛋白(Zein)纳米纤维膜,对所制备的纤维膜进行了扫描电镜(SEM)、X射线衍射(XRD)、远红外(FTIR)表征。SEM结果表明:质量分数为30%的Zein溶液所制备的纳米纤维形貌最佳。XRD结果显示静电纺丝未改变Zein的晶相。FTIR结果表明:电纺并未改变Zein的主要结构。对Zein纳米纤维膜进行了紫外线交联和戊二醛交联,并对交联后的纤维膜进行了比表面积和拉伸性能测试。结果表明:交联后Zein纳米纤维膜的力学性能有显著提高,但戊二醛交联引起了比表面积的急剧减小,会对纤维膜的通透性造成较大影响;而紫外线交联的纳米纤维膜的力学性能不仅得到了提高,微观结构也不受影响。     

聚乳酸/聚乙烯醇纳米纤维的制备及结构

以二甲基亚砜为溶剂,制备不同配比的聚乳酸(PLLA)和聚乙烯醇(PVA)的混合溶液,静电纺丝制得PLLA/PVA纳米纤维。采用红外光谱仪、原子力显微镜等对PLLA/PVA纳米纤维结构与性能进行了表征。结果表明:PLLA/PVA纳米纤维中PVA上的羟基与PLLA上的羰基形成了氢键,PLLA与PVA之间存在一定的相互作用,但PLLA/PVA纳米纤维存在相分离现象;混合溶液的PLLA质量分数为11%,PVA质量分数为8%时可以得到较好的PLLA/PVA纳米纤维,但PVA质量分数为6%时出现液滴及珠丝,PVA质量分数为4%时,不能制得纳米纤维。     

PAN-O/MMT复合纳米纤维膜的制备及染料吸附性能

利用静电纺丝法制备了含有不同质量分数(0、1%、3%、5%)有机改性蒙脱土(O/MMT)的聚丙烯腈复合纳米纤维膜,通过亚甲基蓝吸附分析比较了纤维膜的吸附性能。利用粘度、电导率、表面张力分析了MMT的含量对纺丝液性质的影响,利用扫描电子显微镜分析了不同比例O/MMT的加入对所制备的复合纳米纤维的形貌结构的影响,傅里叶变换红外光谱分析结果证实了O/MMT和PAN形成了纳米复合结构,同时借助热重分析仪分析了O/MMT的加入对复合纳米纤维膜热性能的影响。结果表明,随着O/MMT含量的增加,纤维变细、珠节增加,纤维膜的亚甲基蓝吸附能力也同时提高。     

静电纺玉米醇溶蛋白纳米纤维及其药物缓释行为

利用静电纺丝法制备了玉米醇溶蛋白(Zein)、Zein/乙二醛交联纳米纤维,分别制得了负载不同质量药物的载药纳米纤维膜,并对纤维膜形态与结构进行了表征,研究了药物缓释行为。利用扫描电镜(SEM)对交联前后与负载药物后纳米纤维的形貌和直径分布进行了分析;强力测试结果表明,乙二醛交联后的Zein纳米纤维强度提高了近10倍;傅里叶变换红外光谱(FTIR)研究了Zein、乙二醛与药物之间的分子间作用力;紫外可见光(UV-Vis)光谱分析表明,乙二醛交联Zein载药纤维累积释放率比未交联的高且有一定的缓释效果。     

不同纳米粒子对聚乳酸热性能的影响

采用超声辅助、熔融共混的方法,将不同的纳米粒子对聚乳酸(PLLA)进行复合改性,利用热失重分析(TGA)、差示扫描量热法(DSC)、X-射线衍射分析(XRD)、FTIR等测试手段研究了不同纳米粒子对改性材料热性能的影响。研究发现:相同质量分数(1%)的不同纳米颗粒对PLLA的热稳定性的影响不同。含有NH2功能团的纳米SiO2(RNS)和含CH3功能团的纳米SiO2(DNS)的加入促进了PLLA热稳定性,乙烯基笼状倍半低聚硅氧烷(Vinyl-POSS)的加入对PLLA热稳定性影响不明显,而NLY101Ⅰ型纳米CaCO3则引起了PLLA热稳定性的大幅降低。同时,不同纳米粒子的加入对PLLA冷结晶、熔融和结晶都产生了影响。     

聚丙烯酸纳米纤维膜的制备及交联

通过静电纺丝制备聚丙烯酸(PAA)纳米纤维膜,并以乙二醇(EG)为交联剂、硫酸(H_2SO_4)为引发剂,对制备的PAA纳米纤维膜进行热交联,以提高其在水中的稳定性。采用扫描电子显微镜对纤维的表面形貌进行表征,发现当PAA溶液质量分数为9%、交联剂EG质量分数为12%、纺丝电压为20 k V时,溶剂挥发完全,而且纤维直径分布均匀。试验还对交联温度及交联时间进行了研究,发现PAA纳米纤维膜在140℃的热处理条件下形成酯,而在150℃及以上的热处理条件下形成酯和酸酐,且上述交联反应都能在1 h内完成。     

溶液性质对电纺聚乳酸/茶多酚复合纳米纤维膜形貌的影响

为了研究静电纺丝溶液性质对聚乳酸(PLA)/茶多酚(TP)复合纳米纤维膜的形貌与直径的影响,本文借助扫描电子显微镜(SEM)观察不同纺丝溶液条件下纳米纤维膜的外观形貌并计算纤维直径。结果表明:当PLA溶质质量分数为10%时,纤维成纤性最好。而纺丝溶剂采用二氯甲烷(DCM)和N,N-二甲基甲酰胺(DMF)的混合溶剂时,纤维形貌改善明显。同时不同PLA/TP质量混比条件下的纤维直径在380~854nm之间。     

碳酸乙烯酯对聚己内酯/冰乙酸电纺纤维的影响

在聚己内酯(PCL)/冰乙酸(GAC)溶液体系中加入低毒低挥发性溶剂碳酸乙烯酯(EC),采用静电纺丝法成功制备纳米纤维,采用扫描电子显微镜研究了不同EC浓度对制得的纤维形貌和直径的影响。结果表明,当溶液中PCL质量分数为20%,EC体积分数从0%变化到9%时,纳米纤维数量增加,平均直径逐渐变小;当EC体积分数从9%变化到15%时,微米纤维或珠串状纤维数量开始增加,平均直径逐渐变大。对比研究了EC体积分数为9%的溶液与未加EC的溶液的纺丝稳定性,同时对比研究了由这两种溶剂分别制备的纳米纤维膜和微米纤维膜的结构和性能。结果表明,PCL/GAC/EC溶液体系黏度可在24h内保持稳定,满足连续电纺要求;X射线衍射测试结果表明两种纤维膜结晶构型一致,只是结晶度和晶粒大小有所区别;傅里叶变换红外光谱分析结果表明EC对PCL的化学结构没有影响;与微米纤维膜相比,纳米纤维膜的比表面积提高了362.6%,平均孔直径有所减小,接触角有所增大;纳米纤维膜的拉伸断裂应力稍大但断裂应变明显小于微米纤维膜。     

可降解多元混构型纤维的制备及降解性能研究

将聚羟基丁酸戊酸酯(PHBV)、左旋聚乳酸(PLLA)以不同比例共混,采用干法纺丝工艺制备复合可降解纤维。运用扫描电子显微镜和X射线衍射仪对纤维的微观形貌和结构进行分析。确定干法纺丝工艺参数为:卷绕速度28.5 m/min,拉伸倍数3倍,拉伸温度90℃。当PHBV与PLLA质量比为1∶1时,所得纤维强度可达2.8 c N/dtex。通过力学以及结晶性能的变化等研究纤维的降解性能。随降解时间的增加断裂强度与断裂伸长率均呈下降趋势,纤维的规整结构遭到破坏,结晶度有所下降。共混比不同的复合纤维在同一周期内其降解程度不同,当PLLA质量分数达80%,降解周期为50 d时,呈现脆性断裂,断裂强度仅为降解前的1/3。     

聚乳酸/聚酯酰胺复合纳米纤维膜制备及性能

通过溶液聚合和扩链方法合成了主链中含有L–丙氨酸、乙二醇、己内酯的生物可降解聚酯酰胺[P–(CL–EA–CL)],采用红外光谱、核磁共振光谱证明产物合成。将其与左旋聚乳酸(PLLA)共混静电纺丝成膜制备了PLLA/P–(CL–EA–CL)复合纳米纤维膜,探究了不同共混比和接枝比对纤维膜的影响。结果表明,加入P–(CL–EA–CL)改善了纤维膜的力学性能,同时纤维膜的亲水性也得到明显改善。当P–(CL–EA–CL)添加量为30%、接枝比例为1∶4时,共混膜的拉伸强度为11.43 MPa,断裂伸长为56.21%,亲水角由纯PLLA纤维膜的138.2°减小到76.3°。在不同环境的降解实验也发现共混纤维膜具有碱性降解敏感性,细胞毒性测试进一步表征共混膜良好的生物相容性,PLLA/P–(CL–EA–CL)复合纳米纤维膜有生物组织工程领域的应用潜力。     

Effects of hard and soft components on the structure formation,crystallization behavior and mechanical properties of electrospun poly(l-lactic acid) nanofibers

The effects of multi-wall carbon nanotubes (MWCNTs) and poly(ethylene oxide) (PEO) on the structure formation, morphology, crystallization behavior and mechanical property of electrospun poly (l-lactic acid) (PLLA) nanofiber mats were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and mechanical test. If incorporate hard filler, MWCNTs into electrospun PLLA nanofiber, the crystallinity, chain orientation, and crystallization behaviors were almost not influenced by the MWCNTs content owing to the MWCNTs mainly acted as impeding the crystal growth and chain diffusion. If incorporate small content of soft and miscible component, PEO (10 wt%) into the electrospun PLLA and PLLA/MWCNTs nanofibers, the crystallinity and crystallization rate of PLLA in nanofibers were obviously enhanced. The synergistic effect of PEO and MWCNTs in PLLA nanofibers was observed during melt-crystallization behaviors of PLLA/MWCNTs fibers. Based on those results, we found that the chain mobility is an important factor to influence the structure formation and crystallization behaviors in the electrospun nanofibers. Our results indicated that the structure and properties of electrospun nanofibers could be optimized by compounding with hard inorganic filler and soft polymer components.     

Preparation and characterization of zein and zein/poly‐L‐lactide nanofiber yarns

Zein and zein/poly‐L ‐lactide (PLLA) nanofiber yarns were prepared by conjugate electrospinning using coupled spinnerets applied with two high electrical voltages of opposite polarities in this article. Structure and morphology of zein yarns were investigated by SEM and X‐ray diffraction. The results showed that zein yarn consisted of large quantity of fibers with diameters ranging from several hundreds nanometers to a few microns, and zein concentration played a significant role on the diameter of nanofibers in yarns. To improve mechanical property of nanofiber yarns, PLLA was then incorporated with zein. Zein/PLLA composite nanofiber yarns conjugate electrospun from solution with concentration of 7.5% (zein, w/v)/7.5% (PLLA, w/v) exhibited tensile strength of 0.305 ± 0.014 cN/dtex. The composite yarns showed better nanofiber alignment along the longitudinal axis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Conjugate electrospinning of continuous nanofiber yarn of poly(L‐lactide)/nanotricalcium phosphate nanocomposite

The continuous nanofiber yarns of poly(L ‐lactide) (PLLA)/nano‐β‐tricalcium phosphate (n‐TCP) composite are prepared from oppositely charged electrospun nanofibers by conjugate electrospinning with coupled spinnerets. The morphology and mechanical properties of PLLA/n‐TCP nanofiber yarns are characterized by scanning electron microscope, transmission electron microscope, and electronic fiber strength tester. The results show that PLLA/n‐TCP nanofibers are aligned well along the longitudinal axis of the yarn, and the concentration of PLLA plays a significant role on the diameter of the nanofibers. The thicker yarn of PLLA/n‐TCP composite with the weight ratio of 10/1 has been produced by multiple conjugate electrospinning using three pairs of spinnerets, and the yarn has tensile strength of 0.31cN/dtex. A preliminary study of cell biocompatibility suggests that PLLA/n‐TCP nanofiber yarns may be useable scaffold materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

聚多巴胺改性静电纺EVOH–SO_3Li薄膜的热力性能

由静电纺丝技术制备的EVOH–SO_3Li纳米纤维薄膜的力学性能不高,为了改善薄膜的力学性能,采用多巴胺对EVOH–SO_3Li纳米纤维膜进行改性。通过宏观形貌观察、扫描电子显微镜、傅立叶变换红外光谱分析这三种测试方法相结合,表明多巴胺粘附在纳米纤维上,并在纤维膜上进行自聚形成聚多巴胺(PDA)。热失重分析结果表明,热失重为10%时PDA改性后的隔膜较未改性的EVOH–SO_3Li纯膜提高了67℃。拉伸性能测试结果表明,浸泡浓度为0.015 mol/L时,PDA改性后的隔膜拉伸强度比纯膜提高了11.89 MPa。PDA改性后薄膜的孔隙率有所下降但吸液率提升明显,最高达到了480%。     

Structure and process relationship of electrospun bioabsorbable nanofiber membranes

An electrospinning method was used to fabricate bioabsorbable amorphous poly(d,l-lactic acid) (PDLA) and semi-crystalline poly(l-lactic acid) (PLLA) nanofiber non-woven membranes for biomedical applications. The structure and morphology of electrospun membranes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and synchrotron wide-angle X-ray diffraction/small angle X-ray scattering. SEM images showed that the fiber diameter and the nanostructured morphology depended on processing parameters such as solution viscosity (e.g. concentration and polymer molecular weight), applied electric field strength, solution feeding rate and ionic salt addition. The combination of different materials and processing parameters could be used to fabricate bead-free nanofiber non-woven membranes. Concentration and salt addition were found to have relatively larger effects on the fiber diameter than the other parameters. DSC and X-ray results indicated that the electrospun PLLA nanofibers were completely non-crystalline but had highly oriented chains and a lower glass transition temperature than the cast film.     

Electrospinning and crosslinking of zein nanofiber mats

Electrospinning processing can be applied to fabricate fibrous polymer mats composed of fibers whose diameters range from several microns down to 100 nm or less. In this article, we describe how electrospinning was used to produce zein nanofiber mats and combined with crosslinking to improve the mechanical properties of the as‐spun mats. Aqueous ethanol solutions of zein were electrospun, and nanoparticles, nanofiber mats, or ribbonlike nanofiber mats were obtained. The effects of the electrospinning solvent and zein concentration on the morphology of the as‐spun nanofiber mats were investigated by scanning electron microscopy. The results showed that the morphologies of the electrospun products exhibited a zein‐dependent concentration. Optimizing conditions for zein produced nanofibers with a diameter of about 500 nm with fewer beads or ribbonlike nanofibers with a diameter of approximately 1–6 μm. Zein nanofiber mats were crosslinked by hexamethylene diisocyanate (HDI). The tensile strength of the crosslinked electrospun zein nanofiber mats was increased significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:380–385, 2007     

静电纺PLLA/PCL有序纤维的制备及性能研究

以三氯甲烷为溶剂,按聚乳酸(PLLA)/聚己内酯(PCL)质量比70/30配制质量分数3%的溶液进行静电纺丝,接收装置为转筒,电压为10 kV,接收距离为25 cm,推进速度为1.0 mL/h,制备PLLA/PCL有序纤维膜。通过对有序纤维膜进行扫描电镜、X射线衍射、动态力学性能以及力学性能测试,讨论了转筒的表面线速度对PLLA/PCL有序纤维膜性能的影响。结果表明:随着转筒表面线速度的增加,收集的有序纤维接近于平行排列,纤维的排列有序度提高;转筒表面线速度为3.75 m/s时,收集的有序纤维膜的晶粒尺寸及结晶度达到最大值,拉伸强度也达到最大值;转筒表面线速度大于3.75 m/s,收集的有序纤维膜的结晶度和晶粒尺寸减小,拉伸强度降低;转筒表面线速度为3.75 m/s时,得到的PLLA/PCL有序纤维膜的综合性能最好。     

Biodegradable poly(l-lactide)/poly(?-caprolactone)-modified montmorillonite nanocomposites: Preparation and characterization

New nanocomposites were prepared by melt blending poly(l-lactide) (PLLA), poly(?-caprolactone) (PCL), and organically modified montmorillonite (OMMT). The obtained nanocomposites showed enhanced tensile strength, modulus and elongation at break than that of PLLA/PCL blends. The dynamic mechanical analysis showed the increasing mechanical properties with temperature dependence of nanocomposites. Wide-angle X-ray diffraction analysis and transmission electron microscopy indicated that the material formed the nanostructure. Adding OMMT improved the thermal stability and crystalline abilities of nanocomposites. The morphology was investigated by environmental scanning electron microscopy, which showed that increasing content of OMMT reduces the domain size of phase-separated particles. The specific interaction between each polymer and OMMT was characterized by the Flory-Huggins interaction parameter, B, which was determined by the equilibrium melting point depression of nanocomposites. The final values of B showed that PLLA was more compatible with OMMT than PCL.     

Biocomposites based on lignin and plasticized poly(L‐lactic acid)

In this research work, biocomposites based on a ternary system containing softwood Kraft lignin (Indulin AT), poly‐L ‐lactic acid (PLLA) and polyethylene glycol (PEG) have been developed. Two binary systems based on PLLA/PEG and PLLA/lignin have also been studied to understand the role of plasticizer (i.e., PEG) and filler (i.e., lignin) on the overall physicomechanical behavior of PLLA. All samples have been prepared by melt‐blending. A novel approach has also been introduced to improve the compatibility between PLLA and PEG by using a transesterification catalyst under reactive‐mixing conditions. In PEG plasticized PLLA flexibility increases with increasing content of PEG and no significant effect of the molecular weight of PEG on the flexibility of PLLA has been observed. Differential scanning calorimetry and size‐exclusion chromatography along with FTIR analysis show the formation of PLLA‐b‐PEG copolymer for high temperature processed PLLA/PEG systems. On the other hand, binary systems containing lignin show higher stiffness than PLLA/PEG system and good adhesion between the particles and the matrix has been observed by scanning electron microscopy. However, a concomitant good balance in stiffness introduced by the lignin particles and flexibility introduced by PEG has been observed in the ternary systems. This study also showed that high temperature reactive melt‐blending of PLLA/PEG leads to the formation of a segmented PLLA‐b‐PEG block copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

In vitro degradation of PLLA/nHA composite scaffolds

Porous Poly‐l ‐lactide (PLLA) scaffolds and PLLA/nanohydroxyapatite (nHA) composite scaffolds with interconnected pore networks and a porosity of over 90% were fabricated with lyophilization techniques. In this study, the degradation behavior of PLLA and PLLA/nHA composite scaffolds is investigated over 8 weeks in phosphate buffer solution at 37°C. Thermal analysis using differential scanning calorimetry (DSC) showed that the percent crystallinity of all the samples increased by approximately 10%, which represents a considerable increase in the glass transition temperature. The melting range enthalpy of the scaffolds did not change to lower temperatures as would be expected. The spectroscopic analysis performed by Fourier transform infrared spectroscopy suggested that nHA particles should not appreciably affect the absorbance pattern when evenly mixed with the PLLA. This is consistent with the analysis of the scaffold microstructure and morphology with scanning electron microscopy, which drew a low content of nHA with no significant effect on solvent crystallization or pore structure. The compressive modulus and the yield strength of the scaffolds were investigated in conjunction with the study of their degradation rates. In comparison with the mechanical properties of the PLLA scaffolds, which remained largely unchanged, those of the PLLA/nHA composite scaffolds decreased as the degradation progressed. POLYM. ENG. SCI., 54:2571–2578, 2014. © 2013 Society of Plastics Engineers