静电纺聚偏氟乙烯多尺度树枝结构纳米纤维的制备及其应用研究
本文选题:静电纺丝 + 聚偏氟乙烯 ; 参考:《天津工业大学》2017年博士论文
【摘要】:自然界经过长期的进化发展,创造出了诸多结构特殊、性能优异的物质,吸引了国内外大量学者的探索研究。通过深入了解自然界创造出的这些生物的特性,可为人们仿造自然并创造出新型的材料与结构提供思路。随着纳米纤维的快速发展,静电纺丝已经成为一种连续制备纳米纤维的常用技术,由于其原料来源范围广、纤维结构可调性强等技术优势,为纳米仿生结构的研究提供了技术保障。本文综述了静电纺丝制备的各种仿生异形纳米纤维以及仿生异形纳米纤维在各个领域的应用。基于静电纺丝技术的原理,通过调控聚合物的溶液性质及工艺参数,采用一步法电纺制备了多尺度树枝结构纳米纤维,利用高速摄像观察了纺丝射流在电场中的运动情况,揭示了树枝状纳米纤维的成形机理,为树枝状纳米纤维的可控制备奠定了基础;树枝状结构极大的减小了纤维膜的孔径尺寸,大幅度提高了纤维膜的比表面积,利用这些优点将制备的树枝状纳米纤维膜应用于空气过滤和液体过滤,探讨纤维膜的树枝状结构与过滤性能之间的关系;通过吡咯单体原位聚合和与高锰酸钾氧化还原反应制备了聚偏氟乙烯(PVDF)负载二氧化锰(Mn02)(Mn02@PVDF)树枝状纳米纤维膜,并研究其对Pb2+吸附性能;通过溶液聚合和一步电纺技术制备了 pH响应型PVDF接枝聚丙烯酸(PVDF-g-PAA)树枝状纳米纤维膜,并研究了其在不同pH条件下智能油水分离性能。论文主要研究内容如下:通过向高聚物溶液中加入有机支化盐四丁基氯化铵(TBAC),采用一步法电纺制备了 PVDF树枝状纳米纤维膜。研究了盐的种类、盐的添加量、纺丝液浓度和纺丝工艺参数对纤维膜树枝状形貌的影响。结果表明,加入有机支化盐制备的纳米纤维中树枝状含量明显高于加入无机盐制备的纳米纤维,TBAC浓度为0.1 mol L-1,纺丝电压为25 kV,接收距离为15 cm,挤出速率为1 mL h-1时,制得的纳米纤维树枝状形貌最佳。树枝状纳米纤维由主干纤维和分支纤维组成,其中,主干纤维直径为100 nm-500 nm,分支纤维直径为5 nm-100 nm。通过高速摄像观察纺丝射流在电场中的运动分析推断树枝状纳米纤维的形成机理,结果表明,树枝状纳米纤维是由射流劈裂形成的。在树枝状纳米纤维膜可控制备的基础上,考察了树枝状结构对纤维膜孔径尺寸、比表面积、力学性能及亲水性能的影响,结果表明,树枝状结构极大的减小了纤维膜的孔径尺寸,大幅度的提高了纤维膜的比表面积和力学性能,且纤维膜的亲水性能有所提升。对比分析了不同面密度的树枝状纳米纤维膜和常规纳米纤维膜对0.26μm NaCl粒子的过滤性能,结果表明,树枝状纳米纤维膜的过滤性能明显优于常规纳米纤维膜,面密度仅为1.0 g/m2的树枝状纳米纤维膜的过滤效率高达99.999%,且过滤阻力仅为124.2 Pa。测试了不同树枝状含量的纳米纤维膜对0.3μm的聚苯乙烯微粒的截留率,结果显示,厚度为30±2 μm的树枝状结构含量最多的纳米纤维膜的截留率高达99.9%,在0.1 MPa压力下纯水通量达到23930 L/m2h,且由过滤后纤维膜的截面图可以发现,该过滤以表层过滤为主,有助于反冲清洗重复利用。基于树枝状结构纳米纤维膜更大的比表面积的优势,通过吡咯单体的原位聚合在PVDF/TBAC树枝状纳米纤维膜的表面均匀包覆一层聚吡咯(PPy),然后通过PPy与高锰酸钾之间的氧化还原反应在其表面负载MnO2,制得MnO2@PVDF树枝状纳米纤维膜,并将其应用到Pb2+吸附领域。研究结果表明,MnO2均匀的负载在纤维膜表面且负载MnO2后纤维膜亲水性增强。测试了该纤维膜对Pb2+的吸附性能,结果显示纤维膜对Pb2+最大吸附量为318.47 mg/g,吸附过程符合准二级吸附动力学和Langmuir等温吸附模型,吸附热力学研究结果表明吸附过程为吸热反应,升高温度有利于吸附反应的进行,该吸附剂对Pb2+的吸附具有较好的选择性和重复利用性。由XPS分析可知,吸附过程中吸附剂表面的锰氧化物与溶液中的Pb2+之间发生质子交换,而达到的吸附作用。利用多乙烯多胺(PEPA)的脱氟脱氢作用,通过溶液均相聚合和静电纺丝技术制备出一种具有pH响应性的PVDF-g-PAA树枝状纳米纤维智能膜。研究了 PEPA和丙烯酸加入量对纤维膜形貌结构、力学性能和亲水性能的影响,结果表明,加入PEPA后,成功引入了碳碳双键,当PEPA加入量低于10%时,纤维膜的树枝状形貌良好:随着PEPA加入量的增加,纤维膜力学性能下降,最终选用PEPA加入量为5%;随着丙烯酸加入量的增加,树枝状分支纤维含量逐渐增加、纤维膜孔径逐渐减小且力学性能有所下降,当丙烯酸加入量为10%时,纤维膜呈现良好的pH响应润湿性。进一步考察了纤维膜的智能油水分离性能,结果表明,通过改变介质pH,该纤维膜仅在重力驱动下能实现分离水或分离油,且具有较高的分离效率(99%)和渗透通量(9600 L/m2h)。本文采用一步法静电纺丝技术可控制备出PVDF树枝状纳米纤维,树枝状结构赋予纤维膜的小孔径和大比表面积,在空气/液体过滤、重金属离子吸附和油水分离领域均显示出广阔的应用前景和巨大的潜在应用价值,为静电纺纳米纤维的应用开辟了一条新的道路。
[Abstract]:After a long period of evolution, nature has created a lot of material with special structure and excellent performance, which has attracted a lot of scholars at home and abroad. Through the thorough understanding of the characteristics of these creatures created by nature, it can provide ideas for people to imitate nature and create new materials and structures. With the rapid development of nanofibers, the rapid development of the materials and structures can be made. Development, electrospinning has become a common technique for continuous preparation of nanofibers. Due to its wide range of raw materials and strong tunability of fiber structure, it provides a technical guarantee for the study of nano biomimetic structures. The application of various fields. Based on the principle of electrostatic spinning technology, multi-scale dendritic structure nanofibers were prepared by one step electrospun by controlling the solution properties and technological parameters of the polymer. The movement of the spinning jets in the electric field was observed by high-speed photography, and the forming mechanism of the dendrimer like nanofibers was revealed. The controllable preparation of nanofibers laid the foundation, the dendrimer structure greatly reduced the size of the fiber membrane and greatly improved the specific surface area of the fiber membrane. Using these advantages, the dendritic nanofibrous membranes were used in the air filtration and liquid filtration, and the relationship between the dendritic structure of the fiber membrane and the filtration performance was discussed. Polyvinylidene fluoride (PVDF) supported manganese dioxide (Mn02) (Mn02@PVDF) dendrimer nanofibrous membrane was prepared by in-situ polymerization of pyrrole and oxidation and reduction with Potassium Permanganate, and the adsorption properties of Pb2+ were studied. PH responsive PVDF graft polyacrylic acid (PVDF-g-PAA) dendrimer nanoparticles were prepared by solution polymerization and one step electrospun technology. The properties of intelligent oil and water separation under different pH conditions were studied. The main contents of this paper were as follows: by adding organic branched salt four Butyl Ammonium Chloride (TBAC) into the polymer solution, the PVDF dendrimer nanofibrous membrane was prepared by one step electrospun. The types of salt, the amount of salt, the concentration of spinning solution and the spinning machine were studied. The results show that the dendrimer content of nanofibers prepared by adding organic branched salts is obviously higher than that of nanofibers added to the inorganic salts. The TBAC concentration is 0.1 mol L-1, the spinning voltage is 25 kV, the receiving distance is 15 cm and the extrusion speed is 1 mL H-1, and the dendrimer morphology of the nanofibers is obtained. The dendritic nanofibers are composed of backbone fibers and branch fibers, in which the diameter of the main fiber is 100 nm-500 nm and the diameter of the branch fiber is 5 nm-100 nm.. The formation mechanism of the dendrimer nanofibers is deduced by the motion analysis of the spinning jets in the electric field by high-speed photography. The results show that the dendritic nanofibers are split by the jet. On the basis of the controllable preparation of the dendrimer nanofiber membrane, the influence of the dendritic structure on the pore size, specific surface area, mechanical properties and hydrophilic properties of the fiber membrane was investigated. The results showed that the dendrimer structure greatly reduced the diameter of the fiber membrane, and greatly improved the specific surface area and mechanical properties of the fiber membrane. The hydrophilic properties of the membrane have been improved. The filtration performance of the 0.26 m NaCl particles with different dendrimers and conventional nanofibrous membranes with different surface density is compared and analyzed. The results show that the filtration performance of the dendrimer nanofiber membrane is obviously better than that of the conventional nanofiber membrane and the dendrimer membrane with a surface density of only 1 g/m2. The efficiency is up to 99.999%, and the filtration resistance is only 124.2 Pa.. The retention rate of polystyrene particles with different dendrimers content of nanofiber film to 0.3 mu m is measured. The result shows that the interception rate of the nanofiber film with the most thickness of 30 + 2 mu m is up to 99.9%, and the pure water flux is 23930 L/m2h under the 0.1 MPa pressure. The cross section of the filtered fiber membrane can be found that the filter is dominated by surface filtration and helps to reuse the backflushing cleaning. Based on the advantage of the larger specific surface area of the dendritic structure nanofiber membrane, a layer of polypyrrole (PPy) is uniformly coated on the surface of the PVDF/TBAC dendrimer nanofiber membrane by the in-situ polymerization of the pyrrole monomer, and then through the P The redox reaction between Py and Potassium Permanganate was loaded on the surface of MnO2 to produce MnO2@PVDF dendrimer nanofibrous membrane and applied to the field of Pb2+ adsorption. The results showed that the uniform load of MnO2 was on the surface of the fiber membrane and the hydrophilic property of the fiber membrane was enhanced after the load of MnO2. The adsorption properties of the fiber membrane to Pb2+ were tested and the results showed fiber. The maximum adsorption capacity of the membrane to Pb2+ is 318.47 mg/g. The adsorption process conforms to the quasi two class adsorption kinetics and Langmuir isothermal adsorption model. The adsorption thermodynamics research results show that the adsorption process is endothermic reaction and the elevated temperature is beneficial to the adsorption reaction. The adsorbent has good selectivity and reutilization on the adsorption of Pb2+. It is divided into XPS. In the process of adsorption, the adsorption effect of proton exchange between the manganese oxide on the adsorbent surface and the Pb2+ in the solution is achieved. Using the defluorination and dehydrogenation of polyethene polyamine (PEPA), a kind of PVDF-g-PAA dendritic nanofiber intelligent membrane with pH response is prepared by the solution homogeneous polymerization and electrospinning technology. The effects of PEPA and acrylic acid addition on the morphology, mechanical properties and hydrophilic properties of the fiber membrane were investigated. The results showed that carbon carbon double bonds were successfully introduced after the addition of PEPA. When the addition of PEPA was less than 10%, the dendritic morphology of the fiber membrane was good: with the increase of the amount of PEPA, the mechanical properties of the fiber membrane decreased, and the final selection of PEPA was 5%. With the increase of the amount of acrylic acid added, the content of branched branching fibers increased gradually, the pore size of the fiber membrane decreased and the mechanical properties decreased. When the amount of acrylic acid added to 10%, the fiber membrane showed a good pH response wettability. The intelligent oil and water separation performance of the fiber membrane was further investigated. The results showed that the fiber was changed by changing the medium pH. The membrane can only separate water or separate oil under the drive of gravity, and has high separation efficiency (99%) and permeation flux (9600 L/m2h). In this paper, one step method of electrostatic spinning can be used to control the preparation of PVDF dendrimer nanofibers. The dendritic structure gives the small pore size and large specific surface area of the fiber membrane, and it is filtered in air / liquid and heavy metal is removed. The fields of sub adsorption and oil and water separation show wide application prospects and great potential application value, which opens a new way for the application of electrostatically woven nanofibers.
【学位授予单位】:天津工业大学
【学位级别】:博士
【学位授予年份】:2017
【分类号】:TQ342.712
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