【作者】 薛鹏飞；

【导师】 吴驰飞；

【作者基本信息】 华东理工大学 ， 材料学， 2012， 博士

【摘要】 本文首次采用炭黑作为一种新型高折射率粒子来制备高折射率复合材料,并通过炭黑改性来改善高折射率无机粒子的各项物理化学特性,并对炭黑／聚合物高折射率复合材料的制备和特性进行系统研究。本文对炭黑的改性和光学特性研究,并基体与无机粒子之间的相互作用及高折射机理进行的研究,对今后进一步研究有机／无机高折射率复合材料性能有很好的启发和实践指导作用。论文的主要研究内容如下：1.对于炭黑样品,采用了不同条件下氧化处理和超声处理等改性方法,得到氧化炭黑(OCB)和超声处理炭黑(UCB),使炭黑的表面、微结构和电子结构发生多种变化,并通过Raman、XRD、HRTEM、TGA、BET和EELS等测试手段对改性炭黑的结构变化进行了表征,得到了一系列的改性炭黑的微观结构参数,如石墨层尺寸、sp2/sp3-杂化碳原子比值、π-π*键位置等,并通过这些不同来获得需要的微观结构的CB。适度的氧化会使CB形成一定的有序结构,而超声处理则会有一个相反的作用。炭黑样品的sp2杂化碳含量与样品微结构的有序度是密切关联的,通常sp2杂化碳含量越大,其有序度也越高。2.研究了各种改性方法制备得到的改性炭黑的光谱特性,并考察了其微结构变化即sp2杂化碳原子及电子结构与光学性能的关系。这些改性炭黑包括OCB、UCB和PVA包覆CB。研究发现CB粒子的光学特性和消光行为是由材料中的中程有序度决定的,尤其是相邻或聚集在一起的sp2键合环的数量,CB粒子中碳碳sp2杂化键合区域尺寸的增加,会降低样品的光学带宽,但亦会增强其UV吸收,反之亦然。另外,PVA包覆炭黑会显著降低其UV和VIS区的吸光度。总之,通过不同的改性方法来获得所需微结构及性能的CB粒子,可以有效的改善炭黑的光吸收性能及拓展其在光学及高折射率领域的应用。3.通过酰氯化改性炭黑(CB-COC1)存在下,联苯四羧酸二酐和二氨基二苯醚缩合,并经过热亚胺化反应制备得到聚酰亚胺(PI)/炭黑杂化制备高折射复合材料。红外光谱证实了PI和CB-COC1之间的化学键合作用的存在,并对PI膜的各项性能有显著影响。复合薄膜的结构发生了变化,其热分解温度增加,玻璃化转变温度也有轻微增大。随着CB-COC1含量的增加,复合薄膜的拉伸模量和强度增加,断裂伸长率减小。CB以及五元胺环和CB的芳香环之间的相互作用对复合薄膜的光学性能的影响也进行了讨论。复合薄膜在633nm处的折射率随着CB含量的增加在1.711～1.833范围内变化。复合薄膜折射率的增加不只是因为CB-COC1粒子的本征高折射,更主要的是因为分子内和分子间电子的相互转移(CT)作用。利用荧光光潜验证了这种CT相互作用的存在；并根据实验结果及折射率变化的影响因素,在Lorentz-Lorenz方程中定义了一个新的项式即CT相互作用因子修郑了Lorentz-Lorenz方程。4.高折射率且低密度的CB粒子是一种优异的制备高折射率复合材料的选择。通过PVA的炭二亚胺酯化反应对CB进行官能化,水溶性聚合物PVA作为聚合物基体,利用在PVA基体中混合入水溶性高折射添加剂(PVA共价官能化CB)以达到增加折射率的目的,制备得到一种新的有机/无机杂化高折射率复合薄膜。透射电镜照片显示CB粒子在PVA基体中分散良好。PVA-es-CB/PVA复合薄膜的折射率随PVA-es-CB体积分数的增加而线性增大,而其Abbe数则成相反的变化趋势,这也表明制备到的复合薄膜可以通过改变其组成来调节其光学特性。利用Maxwell-Garnett理论给出的理论曲线比使用Lorentz-Lorenz方程计算得到的值要低,Lorentz-Lorenz方程对于大多数实验值有更好的匹配性。更多还原

【Abstract】 In this paper, we report a novel high refractive index (RI) additive-functionalized carbon black (CB), especially to deserve to be mentioned, CB has not been reported to incorporate into polymer matrix to fabricate high RI nanocomposites. The optical properties of CB nanoparticles modified by different experimental methods and their relation with particle structural variations were also studied. The mechanism of high RI CBs and the compatibility between CBs and polymer matrix were investigated. It may be a good inspiration and practical guidance for further study of high RI organic/inorganic composites. The main content as follow:1. The microstructure and electronic structure of modified CB were investigated by Raman spectroscopy, transmission electron microscopy, electron energy loss spectroscopy and ultraviolet spectroscopy. The modified CB samples include oxidised CB (OCB) and ultrasound-treated CB (U-CB) under different modification conditions. Typical parameters, such as graphene layer size, the ratio of sp2/sp3-hybridised carbon atoms, andπ-π* band position, provide information on the microstructure and electronic structure, and these parameters also allow discrimination between different modified CB samples to achieve a desired structure. Oxidation conditions could be carefully chosen to prevent excessive corrosion and form an ordered structure. However, ultrasound has a reverse effect; the graphite layers of the CB samples were exfoliated, and a disordered microstructure was visible. The results indicate that increasing sp2-island size in CB samples increases the order of CBs.2. We study the micromorphology, spectral behavior and electronic structure of modified CBs. The modified CB samples, including OCB, UCB and poly (vinyl alcohol)-encapsulated CB (PVA-CB) are investigated. The aim is to show that the microstructure of the investigated carbon materials correlates with the electronic structure and optical properties in this case with the predominant carbon hybridization. Characterization parameters of optical properties and the extinction behavior are found to be strongly affected by the microstructure and the content of sp2 hybridization of the C atoms. The lower the content of sp2 hybridized carbon, the lower the UV peak position in wavelength and the UV absorption. In addition, PVA-encapsulated-CB particles showed a low absorbance in UV and visible light range. Our results imply that optical properties of CB are significantly altered within its modification methods. Overall, this study is useful to get a better knowledge of the structure-optical properties correlations through the different modification experiments of CB, and also a step toward the possibilities for further optical or high RI application.3. The high RI composite films based on polyimide (PI) and chloride modified CB (CB-COC1) were prepared by conversion of biphenyltetracarboxylic dianhydride and 4,4’-oxydianiline in the presence of CB-COC1, followed by thermal imidization. The presence of chemical bonds between PI and CB-COC1, proved by FTIR spectra of the composites, has a considerable effect on the properties of PI films. The PI/CB-COC1 membranes showed changed morphology compared to reference membranes without CB-COC1. The hybrid films showed an increase in thermal decomposition temperature and a slightly enhanced glass transition temperature. On their mechanical properties, the modulus and ultimate strength of the hybrid films increased and elongation at break decreased with increased CB-COC1 content. The effect of CBs and the interaction between the five-membered imide rings and aromatic rings of CBs on the optical properties of the resulted PI/CB nanocomposites was also discussed. The off-resonant refractive indices of the prepared hybrid films at 633 nm were in the range of 1.711-1.833 as the CB content increased from 0 to 10 wt%. According to the comparison of theory and experimental values, it demonstrates that the increasing of refractive index is mainly from the contribution of the increase in charge transfer interaction between PI and CB. Theoretical equation based on the modified Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values.4. High RI CB particles with low densities would be an optimal candidate for high RI nanocomposite. Nano-CB/polymer composites with high RI were fabricated from poly (vinyl alcohol) (PVA) and covalently functionalized CB (PVA-cs-CB) by simple esterification reaction. Transmission electron microscope showed that a uniform aggregate of PVA-es-CB nanoparticles with a size smaller than 100 nm formed in the nanocomposite films. Ellipsometric measurement indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.52-1.598 linearly increased with the PVA-es-CB volume content. Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The hybrid films also revealed relatively good surface planarity, thermal stability, and optical transparency更多还原