【作者】 夏苏；

【导师】 王政；

【作者基本信息】 中国人民解放军军事医学科学院 ， 生物医学工程， 2009， 硕士

【摘要】 在当代,突发传染病疫情、生物恐怖事件和生物安全事故对国家安全、社会稳定和民众健康造成严重威胁,为此新型生物防护装备、技术和材料的研究受到了世界各国的重视。静电纺丝,就是在高压静电场条件下,聚合物溶液或熔体在静电力作用下经拉伸而获得细小纤维的一种技术方法。利用静电纺丝技术获得的纤维直径范围一般在几十纳米至几微米之间,因此静电纺丝制备的纤维材料具有比表面积大、孔隙尺寸小的特点,所以在生物防护领域,特别是对微生物气溶胶防护方面具有广阔的应用前景。聚氨酯(PU),具有良好的化学物理特性,成熟的工业化生产工艺,特别是成纤性能良好,适合制作纤维尤其是弹性纤维材料,所以非常适合采用静电纺丝方法来制备纳米级或亚微米级功能纤维材料。目前,国内外关于聚氨酯静电纺丝纤维材料用于微生物防护的研究报道较少。本文采用静电纺丝方法,以四氢呋喃(THF)和二甲基甲酰胺(DMF)为溶剂,制备了PU静电纺丝纤维材料并进行抗菌功能改性,研究了该材料对微生物的防护性能,为制备一种新型生物防护材料进行了探索。本文首先以PU为原料,THF/DMF为溶剂,制备了PU静电纺丝纤维,并研究了THF/DMF质量比,溶液质量分数,纺丝电压和接收距离四个因素对PU静电纺丝纤维形貌的影响。采用SEM观察PU静电纺丝纤维的形貌,并分析计算其平均直径。结果表明,纤维直径均匀性随THF/DMF质量比增大而下降。由于随着溶剂的改变,溶液的粘度、电导率、挥发性也相应改变,这些因素的相互竞争影响纤维直径的变化,使纤维平均直径变化表现出复杂性,当THF/DMF为5/5时,可得到形貌和直径都较为理想的PU静电纺丝纤维。纤维平均直径随溶液质量分数增大而增大,这与大多数聚合物规律相一致。纤维直径均匀性随溶液质量分数增大而下降。在该体系下,溶液质量分数为10%时可得到形貌理想,直径细小的PU静电纺丝纤维。在25~40kV电压范围内,PU溶液均能形成喷射流,静电纺丝获得PU纤维。喷射流随电压的增大而变得不稳定,不利于接收器收集纤维。但电压的增大对纤维直径和均匀性没有表现出明显的规律性。在接收距离分别为28cm和24cm时得到的PU静电纺丝纤维平均直径的最大值和最小值,但其对PU静电纺丝纤维直径和均匀性也没有表现出明显的规律性。综合考虑PU静电纺丝纤维平均直径、形貌、喷射流稳定性,在温度为(18-20)℃、湿度为(10-15)%条件下,确定了较佳工艺参数如下:THF/DMF质量比为5/5,溶液质量分数为10%,纺丝电压为32.5kV,接收距离为25cm,纺丝液流量为12ml/h。在该工艺参数下可得到平均直径为230nm,形貌理想的PU静电纺丝纤维材料。该PU静电纺丝纤维材料还表现出较好的透湿性能和力学性能,其试样透湿量均超过8800 g/(m2·d),断裂应力分别为10.1MPa和8.2MPa。在THF/DMF质量比为5/5,溶液质量分数为10%的PU溶液中分别加入、载银二氧化钛、TCS、TCC、PCMX、HM-98、ε-PLYS六种不同类型的抗菌剂,其中抗菌剂在PU静电纺丝纤维材料中的质量分数为5%。在适宜的工艺条件下制备出含不同抗菌剂的PU静电纺丝纤维材料。其中含载银二氧化钛、TCS、HM-98、ε-PLYS的PU静电纺丝纤维材料对金黄色葡萄球菌和大肠杆菌抗菌效果都较为理想,抗菌率均达到了99.8%以上,但添加TCC、PCMX后静电纺丝获得的纤维材料抗菌效果不佳。经过红外光谱分析和SEM测试,结果说明抗菌剂与PU纤维共混较为均匀,添加抗菌剂后共混纤维形貌变化不大,HM-98的加入有利于纤维直径的减小,但降低了PU纺丝液的可纺性。经洗涤后,含载银二氧化钛、TCS的试样基本保持了较好的抗菌效果。综合考虑,本体系中宜选用载银二氧化钛抗菌剂。在适宜的工艺条件下制备了含不同质量分数的载银二氧化钛的PU静电纺丝抗菌纤维。含载银二氧化钛质量分数为1.0,1.5,2.0,2.5,3.0%的PU静电纺丝纤维平均直径分别是1085,937,827,806,664nm。随着载银二氧化钛的质量增加喷射流电荷密度增大,使PU静电纺丝纤维平均直径减小。当含载银二氧化钛质量分数大于1.5%时PU静电纺丝纤维材料对金黄色葡萄球菌和大肠杆菌有良好的抗菌效果,其抗菌率均大于99.99%。PU静电纺丝纤维和载银二氧化钛纳米颗粒混合形式主要是物理形式。载银二氧化钛的加入对纤维材料的力学性能没有显著影响。利用TIS3160分级式滤料测试台采用DOP法测试了平均面密度为104.3g/m2的含载银二氧化钛质量分数为1.5%的PU静电纺丝纤维材料试样对不同颗粒直径的气溶胶的过滤效率,测试气流流速为32L/min。结果表明,试样对气溶胶的过滤效率随颗粒粒径增大呈抛物线形,当颗粒直径为0.11-0.13μm范围时试样过滤效率达到最低,这与材料过滤机理相一致。利用微生物气溶胶过滤效率测试台测试试样对金黄色葡萄球菌和大肠杆菌气溶胶的过滤效率,测试气流流速为28.3L/min。结果表明,试样对大金黄色葡萄球菌平均过滤效率达到99.97%,对肠杆菌气溶胶平均过滤效率达到99.99%。研究表明研制的PU静电纺丝纤维材料具有优良的微生物防护性能和良好的物理力学性能,本研究为开发一种新型生物防护材料奠定了基础。更多还原

【Abstract】 Recently, abrupt outbreak of epidemical disease, bio-terroristic affair and biological accident all threaten seriously the national security, social stability and the health of people. So many countries focused on the researches of advanced bioprotective equipment, technology and materials. Electrospinning is a technology of obtaining ultrafine fibers by the method that polymer solution or melt is drew by electrostatic force in high voltage field. The diameter of fibers made by electrospinning are often between several decades nanometers and several microns. So the electrospun fiber materials have the properties of large specific surface area and small pores between fibers, which result in that they can be applied in bioprotective field, especially in application of protection against microbe aerosol. PU has an excellent chemical and physical properties, can be produced by industrialized technology, fibers especially elastical fibers can be made easily from PU. So it is very suitable for making functional nanofibers or microfibers by electrospinning. At present, there are few reported researches on microbe protection by PU electrospun fiber materials. In this paper, PU ,which was dissolved in mixed solvent made of tetrahydrofuran(THF) and N,N-dimethyl formamide (DMF), nanofibers were prepared by electrospinning, and antibacterial modification of PU fiber materials was done ,then the capability of protection of the fiber materials against microbe was studied. t is hope to lay a foundation for preparing an advanced bioprotective material.PU as a raw material, which was dissolved in THF/DMF was utilized to prepare the electrospun fibers. The effects of mass ratio of THF to DMF, mass concentration of solution, voltage and distance between the needled tip and the collector on the property of electrospun fibers were studied. The morphology of the PU electrospun fibers were observed by scanning electron microscope(SEM),and the average diameter was calculated by analyzing SEM photos.The results showed the uniformity became worse with increasing quantity of THF. The change of solvent resulted in the variety of viscosity, conductivity and volatility of the solution which all effected on the diameter of the fibers, so the change of the average diameter was complicated. Meanwhile the morphology and diameter of the fibers were nice when THF/DMF was 5/5.The fibers become thicker nonuniform with densifying the solution, which was consistent with other polymers. In this system, morphology and diameter of PU electrospun fibers were nice when the concentration of the solution was 10%.The jet can be formed and PU electrospun fibers can be obtained as the voltage between 20kV and 40kV,jet became unstable with increasing voltage which was disadvantaged to collect fibers, and the stability of jet was also effected by temperature and humidity at the same voltage. But voltage did not have a clear law of effect on the average diameter and uniformity of PU electrospun fibers. The average diameter of PU electrospun fibers achieved the maximum at the distance between the needled tip of 28cm and the minimum at distance of 24cm, but distance also did not have a clear law of effect on the average diameter and uniformity of PU electrospun fibers. To consider the average diameter, morphology of PU electrospun fibers and jet stability when the temperature was between 18℃and 20℃,humidity was between 10% and 15%,the better preparation parameters as follows: THF/DMF was 5/5(mass proportion),the solution concentration was 10%,spinning voltage was 32.5kV,distance was 25cm,spinning flow was 12ml/h. In such conditions, PU electrospun fibers with average diameter of 230nm and good morphology were prepared. The PU electrospun fiber materials prepared respectively 3h and 6h had a better performance of water vapor transmission and mechanical properties, and the water vapor transmission was 8800 g/(m2·d), fracture stress was respectively 10.1MPa and 8.2MPa.PU was dissolved in a mixed solvent of THF/DMF(mass proportion,5/5) and the concentration was 10%.Then the solution was added different kinds of antibacterials, including Ag-loaded titanium dioxide, TCS ,TCC, PCMX,HM-98 andε-PLYS,and the weight of antibacterials in PU electrospun fiber materials was all 5%. In the appropriate condition, PU electrospun fiber mateials which contained different antibacterials were prepared. PU eletrospun fiber materials contained 5% Ag-loaded titanium dioxide, TCS, HM-98 andε-PLYS respectively showed high antibacterial activities against Staphylococcus aureus and Escherichia coli, and the both antibacterial efficiency were more than 99.8%,but the addition of TCC,PCMX did not help the fiber materials show high antibacterial activities. The test of IR spectroscopy and SEM indicated that the antibacterial agents and PU electrospun fibers were mixed evenly and the addition of antibacterial agents did not effect the morphology of fibers much, furthermore, the addition of HM—98 was advantaged to decrease the diameter of the fibers, but which reduced the capability of spinning of the PU solution. After washing the samples, the samples contained Ag-loaded titanium dioxide, TCS retained high antibacterial activity. In this system, it was better to choose Ag-loaded titanium dioxide by considering all the factors.In this study, PU electrospun fibers which contained different amounts Ag-loaded titanium dioxide were prepared in the appropriate condition. The average diameter of the PU electrospun fibers containing 1.0,1.5,2.0,2.5 and 3.0% of Ag-loaded titanium dioxide was 1085,937,827,806 and 664nm respectively. The addition of Ag-loaded titanium dioxide increased the charge density in the jets and resulted in the diameter of the PU electrospun fibers became smaller. The PU electrospun fibers materials contianed more than 1.5% of Ag-loaded titanium dioxide had a high antibacterial efficiency against Escherichia coli and Staphylococcus aureus, and the antibacterial efficiency was more than 99.99% .The mixed mode of PU electrospun fiber and Ag-loaded titanium dioxide nanoparticles was a physical form. The addition of Ag-loaded titanium dioxide did not effect the mechanical property of the fibers much. The method of DOP was utilized to test the filtration efficiency of the PU electrospun fiber materials which contained 1.5% Ag-loaded titanium dioxide and the average weight per square meter was 104.3g/m2 to physical particles aerosol with different diameter by TSI 3160 fractional filtration efficiency tester, and the test flow was 32L/min.The result indicated that the curve of the filtration efficiency was parabola with the increase of aerosol particles diameter, when the diameter was between 0.11μm and 0.13μm,the filtration efficiency was the lowest which was consistent with filter theory. The filtration efficiency to both Escherichia coli and Staphylococcus aureus aerosol of the fiber materials were also tested by microbe aerosol efficiency filtration tester, and the test flow was 28.3L/min.The results showed that the filtration efficiency to Staphylococcus aureus aerosol and Escherichia coli aerosol was 99.97% and 99.99% respectively.The study shows the PU electrospun fiber materials prepared have excellent capability of protection against microbe as well as good physical and mechanical capability, the study will lay a foundation for developing a kind of novel bioprotection material.更多还原