【作者】 张小萍；

【导师】 刘力；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 硕士

【摘要】 静电纺丝法制备的纳米纤维材料具有比表面积大、孔径尺寸小且复杂,易表面功能化及物理机械性能优良等特点,因而被广泛应用在光学和化学传感器、高效过滤材料、生物医用材料、纳米复合材料等领域。然而,当前静电纺丝的研究热点主要局限于塑料材料,而橡胶材料的纳米纤维化却鲜见报道,所制得的橡胶纤维形貌也不理想。针对橡胶类材料由于玻璃化转变温度较低,静电纺丝后容易回弹而难以得到纳米级纤维的难题,本论文采用同轴静电纺丝技术,借助外层刚性塑料的保护限制作用,成功制备出直径在400～600nm范围的室温硫化硅橡胶(RTV)纳米纤维。同时,结合稀土β-二酮类有机配合物优异的荧光性能,如发光色彩纯度高、荧光寿命长以及量子产率高等,应用静电纺丝技术制备出具有良好分散结构(纳米尺寸和较高分散度)的高发光效率的稀土纳米纤维复合材料。本论文的主要研究内容如下：(1)应用静电纺丝技术制备了具有较高荧光强度和量子产率的Eu(TTA)3phen/PVP(其中,TTA：噻吩甲酰三氟丙酮,phen：邻菲啰啉,PVP：聚乙烯吡咯烷酮)纳米纤维复合材料(120-170nm)。通过高倍TEM、能谱(EDS)及XRD测试表明,Eu(TTA)3phen在PVP纤维基体中以分子簇或极小颗粒(小于10nm)的状态存在,在分散效果上接近了聚合法制备的单分子级别的分散。荧光性能测试及Judd-Ofelt理论分析表明,这种良好的分散减小了光电子在跃迁过程中非辐射跃迁的速率,从而使纤维的荧光强度和量子效率得到显著提高。(2)应用同轴纺丝技术制备了具有芯-壳结构的RTV／PVP纳米纤维,通过SEM和TEM,考察了聚合物的种类及分子链结构、纺丝液浓度、内外层纺丝液互溶性、推进速度、纺丝电压等对同轴静电纺丝过程及纤维形貌和结构的影响,进而阐明橡胶纳米纤维的形成机制和形貌调控方法,并制备出纳米橡胶纤维。同时,结合RTV优异的耐低温性能及Eu(TTA)3phen优异荧光性能,应用同轴静电纺丝技术制备出了Eu(TTA)3phen/RTV/PVP弹性体基纳米荧光纤维。并结合荧光光谱、荧光寿命和Judd-Ofelt理论深入研究了复合材料的低温荧光性能,探讨了橡胶基体对Eu(TTA)3phen低温荧光性能的贡献以及Eu(TTA)3phen在纤维基体中的分散结构与其荧光性能之间的关系。更多还原

【Abstract】 Nanofibers prepared by electrospinning technique are characterized with large specific surface area, small aperture size, easy to be surface functionalized and excellent mechanical properties, and thus can be widely applied as optical and chemical sensors, high efficient filtering materials, biomaterials, and nano-composite materials, etc. However, the current research focuses of electrospinning are limited to plastic materials and the nano-fibrosis of rubber materials has been rarely reported. As the glass transition temperature (Tg) of rubber-like material is low, the prepared fibers are easy to rebound after electrospinning and thus difficult to obtain nano-fibrous structure. In view of these problems, the coaxial electrospinning technique was adopted in the present work to realize the nano-fibrosis of rubber-like materials by means of the protective effect of outer rigid plastic materials. Finally, the room temperature vulcanized silicone rubber (RTV) nanofiber with the diameter in the range of 400～600 nm had been successfully prepared by coaxial electrospinning. Besides, in combination of the excellent fluorescent properties of rare-earthβ-diketone complexes such as extremely sharp emission bands, long lifetime, and potential high internal quantum efficiency, rare-earth complex/composite nanofibers with good dispersion state and outstanding optical properties were successfully prepared by electrospinning. The main works of the present thesis are listed as follows:(1) Eu(TTA)3phen/PVP (TTA=2-thenoyltrifluoroacetone, phen= 1,10-phenanthroline, PVP=polyvinylpyrrolidone) composite nanofibers (120～170nm) with high fluorescent intensity and quantum efficicency were successfully prepared by electrospinning. High resolution TEM, EDS, and XRD measurements revealed that the Eu(TTA)3phen complex predominantly dispersed as molecular clusters and/or nanoparticles with sizes smaller than 10nm in the PVP fiber matrix. This kind of distribution state of Eu(TTA)3phen was similar as the unimolecular distribution of the complex units along macromolecular chains fabricated by copolymerization. Fluorescence investigation and Judd-Ofelt analysis revealed that the fine dispersion of Eu(TTA)3phen decreased the nonradiative transition rate and further resulting in the significant enhancement of the fluorescent intensity and quantum efficiency of the composite nanofiber.(2) The RTV/PVP nanofibers with core-sheath structure were successfully prepared by coaxial electrospinning. SEM and TEM measurements were applied to investigate the effects of polymer chain structure, solution concentration and viscosity, solvent miscibility, electrospinning rate, and driving voltage on the co-axial electrospinning process and morphology of electrospun fibers; and thus to provide some references for the elucidation of co-axial electrospinning mechanism and fiber morphology control methods. Moreover, combined with the excellent low temperature performance of RTV and outstanding fluorescent properties of Eu(TTA)3phen, the Eu(TTA)3phen/RTV/PVP core-sheath nanofibers were fabricated by coaxial electrospinning. By investigating the fluorescent spectral characteristics, fluorescence lifetime and Judd-Ofelt parameters of the composite, the contribution of RTV matrix to the low temperature fluorescence properties of Eu(TTA)3phen and the relationship between the dispersion of Eu(TTA)3phen and the fluorescent properties of the composite were deeply discussed.更多还原