【作者】 赵冬梅；

【导师】 李坚；

【作者基本信息】 东北林业大学 ， 生物材料工程， 2012， 博士

【摘要】 超细复合纤维凭借其尺寸效应在光、电、磁等许多领域受到人们的青睐。目前制备超细复合纤维的方法有很多,其中成本较低、行之有效的方法就是静电纺丝法。通过静电纺丝法制得的超细复合纤维不仅同时具备基体和填加剂的性能,而且将二者的功能很好地融合到一起,为聚合物基复合材料的使用拓展了广阔的空间。本文以醋酸纤维素(CA)为基体材料,采用静电纺丝法制备了担载农药阿维菌素(AVM)的CA超细缓释复合纤维,并研究了AVM在缓释纤维中的释放行为。又以同样的方法将所制备的金纳米粒子(Au NPs)、银纳米粒子(Ag NPs)和碲化镉量子点(CdTe QDs)复合到CA中制成了纳米复合纤维,通过扫描电镜、透射电镜、X射线衍射仪、红外光谱仪、紫外分光光度计、荧光光谱仪等仪器对粒子和纤维进行表征。最后又将取向纤维通过浇注的方法制成复合膜,并对膜的透明性和拉曼散射效应进行了研究。具体研究内容和结果如下：1.首先确定纯CA的纺丝液浓度,以保证细流在喷射过程中的连续性,为制备复合纤维时确定纺丝液的浓度提供参考。本研究选择丙酮与二甲基甲酰胺(DMF)按体积比为2：1组成的混合物作为溶剂来溶解CA,浓度分别为9wt%、11wt%、13wt%、15wt%、17wt%,对这几种纺丝液进行电纺,从纤维的形貌看,当CA溶液浓度为9wt%时,串珠的形态是多种多样的；当CA浓度增至13wt%时,椭圆形串珠被沿着纤维轴向拉伸；当CA浓度达到15wt%时,被拉长的串珠的数量减少,因此15wt%被确定为电纺复合纤维时CA的最佳浓度。2.制备担载AVM的CA缓释复合纤维,并研究了AVM的释放行为。CA的质量占丙酮与DMF总质量的15%,AVM的量分别占CA质量的0%、5%、10%、20%、30%,通过静电纺丝法对含有不同量AVM的CA混合溶液进行电纺,制备了不同形貌的复合纤维。并对复合纤维进行了表征,X射线衍射(XRD)分析表明纤维表面有少量AVM,大部分在纤维内部形成了结晶,说明AVM受到CA分子链定向排列的影响而产生结晶。热重分析(TGA)和红外(FT-IR)分析表明我们所制备的复合纤维中AVM和CA之间的复合不是通过化学作用而是物理作用实现的。AVM从复合纤维中的释放量由高效液相色谱(HPLC)来确定,由于AVM担载在纤维上的具体位置不同,释放过程分为两步：第一步爆释阶段(纤维外表面上的AVM引起的)和第二步缓释阶段(纤维内部的AVM引起的),这两步释放确保了AVM的稳定释放和有效利用。3.通过柠檬酸钠还原氯金酸(HAuCl4)的方法制备Au NPs,数码照片和紫外及可见光谱(UV-vis)分析证明了Au NPs的合成且粒径均匀,尺寸大约20nm,透射电镜(TEM)分析结果表明Au NPs呈近球形,没有明显的团聚。将Au NPs混入CA溶液中,形成纺丝液,经电纺制备纳米纤维,并对所制备的Au NPs/CA复合纤维的形貌、结晶变化等进行SEM、TEM和XRD表征,结果表明所纺纤维的直径在200-300nm之间,随着Au NPs的加入,纤维的直径变细,结晶度和稳定性均有所提高,且高压并没有对Au NPs产生影响。4.合成了Ag NPs,并通过TEM、UV-vis. XRD对Ag NPs进行了表征,结果表明合成的Ag NPs直径在5-15nm之间且为面心立方结构。然后将Ag NPs混入到CA溶液中,形成纺丝液,经电纺制成纳米纤维。并通过SEM、TEM、FT-IR和TGA对纤维的形貌、结晶变化等进行表征,结果表明所纺纤维的直径在250-750nm之间,Ag NPs在纤维中的分布是均匀的,且Ag NPs改变了纤维的降解机理,降低了CA的结晶度。5.合成了不同颜色的水相CdTe QDs溶液,经荧光光谱和TEM分析表明所合成的CdTe QDs的尺寸约为4nm,荧光效果较好且尺寸分布较窄。CdTe QDs与CA溶液混合通过电纺制备荧光纤维,电镜照片表明纤维的直径在300-700nm之间,QDs被分散到基体CA纤维中。荧光显微镜照片说明QDs被复合到纤维后没有发生明显的尺寸变化和荧光颜色与亮度的改变。FT-IR表明QDs复合到纤维以后其结构没有发生变化,XRD观察到QDs是多晶的,QDs的加入致使复合纤维的结晶度提高,TGA分析表明复合纤维的耐热能力增强。6.制备了直径在250-500nm之间的取向Ag NPs/CA纤维,通过SEM表征了纤维的取向程度。然后用PVA水溶液将纤维浇注成膜,研究了膜的透明性和拉曼效应,纤维成膜后由于PVA填充了松散纤维的空隙,增强了透光率,使纤维由原来的不透明变得透明。而且由于纤维取向,导致纤维沿某方向的偏振效应增大,拉曼效应增强。综上所述,利用静电纺丝法成功地制备了超细缓释复合纤维和纳米复合纤维,实现了缓释纤维中药物的有效释放,并研究了取向纤维成膜后的透明性和拉曼效应。本研究的创新之处体现在以下几方面：1.将醋酸纤维素(CA)和阿维菌素(AVM)的稳定溶液通过静电纺丝的方法制备成CA基药物缓释纤维。AVM在纤维中分散良好,释放稳定,形成的缓释纤维是一种环境友好的新型农药体系,为AVM和CA的应用开辟了新的路径。2.找到了纳米粒子与CA的共溶剂,形成稳定的纺丝液,将金、银纳米粒子(Au NPs、Ag NPs)与CA通过静电纺丝的方法直接复合制备纳米纤维,纳米粒子在纤维中分散良好,性质稳定,为制备功能性纳米纤维提供了新的方法。3.将合成的碲化镉量子点(CdTe QDs)与CA通过静电纺丝的方法复合制备荧光纤维,荧光纤维和荧光纤维膜的颜色与所合成的量子点的粒径尺寸一致,可做为荧光显示、防伪和标识等应用。4.将Ag NPs/CA复合制备取向纤维,纤维取向后又通过浇注成膜的方式,制备了Ag NPs/CA/PVA复合膜,复合膜不仅具有透明性而且拉曼效应增强,为制备光学器件和通信器件等具有拉曼效应的基体材料奠定了基础。更多还原

【Abstract】 Ultrafine fibers with size effect are favored in the optical, electrical, magnetic and many other areas. Electrostatic spinning is cheaper and effective method to prepare ultrafine composite fibers. Electrospinning composite fibers possesses simultaneously performance of matrix and additives, and the performance will also well accommodated, which expands the applications of the polymer composite.In this paper, cellulose acetate (CA) loading of pesticide avermectin (AVM) was electrospun into release composite fibers. The release behavior of AVM from fiber was studied. Gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs) and cadmium telluride quantum dots (CdTe QDs) were compounded into CA to prepare nanofibers by the same method. The particles and fibers are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, UV spectrophotometer, fluorescence spectrometer, etc. Finally, the transparency and SERS effect of casting membranes from the aligned fiber were studied. Specific content and research results are as follows:1. Determine the concentration of the spinning solution to provide a reference for the preparation of composite fibers. CA was dissolved in acetone and dimethyl formamide (DMF) with the volume ratio of2:1. The solution with concentration9wt%,11wt%,13wt%,15wt%and17wt%were electrospun, respectively. When the concentration9wt%, the bead shape is varied; when the concentration increased to13wt%, the ellipse is stretched along the fiber axis; when the CA concentration as high as15wt%, the number of beads stretched are reduced. So15wt%was identified as the optimal concentration.2. Preparation of sustained-release fiber and release behavior of AVM were studied. AVM accounted for0%,5%,10%,20%and30%for the amount of CA. Composite fibers with different morphologies were prepared and characterized. X-ray diffraction (XRD) analysis indicated that AVM crystallized by the influence of alignment of CA molecular chain in electrospinning. Thermal gravimetric analysis (TGA) and infrared (FT-IR) analysis showed the interaction between AVM and CA was not chemical but physical. The release process determined by the high-performance liquid chromatography (HPLC) was divided into two steps:first burst release and later slow release.3. Au NPs was prepared by sodium citrate reduction HAuCl4. Digital photos and ultraviolet and visible spectroscopy (UV-vis) analysis confirmed the synthesis and uniform particle size about20nm of Au NPs. Transmission electron microscopy (TEM) results showed that Au NPs were nearly spherical and there is no obvious aggregation. The crystallinity and stability of fibers are improved. The diameters of spun fibers are between200-300nm and become thinner with the Au NPs increasing.4. Synthesized Ag NPs were characterized by TEM, UV-vis and XRD and results showed that the diameters of Ag NPs with face-centered cubic structure were between5-15nm. Nanofibers were prepared by electrospinning solution and characterized by SEM, TEM, FT-IR and TGA. The diameters of Ag NPs uniformly distributing in fibers are between250-750nm. The degradation mechanism of fibers was changed by Ag NPs.5. CdTe QDs solution with different color was synthesized and characterized by fluorescence spectroscopy and TEM. The diameters of CdTe QDs with good fluorescence and narrow size distribution are about4nm. Fluorescent fibers with uneven diameter between200nm-1μm were prepared by electrospinning mixed solution. QDs are uniformly dispersed in the matrix and there were no significant changes in particle size and fluorescent color and brightness. With the QDs increasing, the crystallinity of the fibers was improved.6. The aligned Ag NPs/CA fibers with diameter between250-500nm were prepared and characterized. The fibers were casted into membrane by PVA solution. The membrane become from opaque to transparent because PVA filled with gap of loose fibers leading to increasing of light transmittance. Raman scattering effect of membrane enhanced because the polarization effects of aligned fibers increased along certain direction.In summary, sustained-release fibers and nanofibers have been successfully prepared by the method of electrospinning in this paper. The innovations in this research were as follows:1. The drug-release fibers were prepared by electrospinning stable solution of cellulose acetate (CA) and avermectin (AVM). AVM was dispersed well in the fibers and the release was stable, which opened a new path for the application of AVM and CA.2. Found the co-solvent of the nanoparticles and CA. Nanoparticles and CA were directly electrospun into nanofibers. The nanoparticles were steadily dispersed in fibers. A new method for preparing functional nano-fibers was provided.3. The fluorescent fibers were prepared by electrospinning the synthesized cadmium telluride quantum dots (CdTe QDs) and CA. The color of the fluorescent fibers and membrane proved the particle size of the synthesized QDs was consistent.4. Ag NPs and CA were spun into the alligned fibers, followed by casting film. The formed composite film was not only transparent but also enhanced for Raman effect, which laid the foundation for the preparation of such matrix material with the raman effect as optical and communications devices.更多还原