【作者】 郭兴梅；

【导师】 刘旭光； 窦涛；

【作者基本信息】 太原理工大学 ， 应用化学， 2010， 博士

【摘要】 光子晶体是由两种或两种以上具有不同折光指数的材料在空间按照一定的周期顺序排列所形成的有序结构材料。光子带隙是光子晶体的最根本特征之一,光子带隙的存在可以使我们如愿地控制光子的运动,制造出高性能的光学器件和通信元件。非密堆积结构的光子晶体由于对光子带隙有展宽作用,更易形成完全光子带隙,因而进一步研究非密堆积结构的光子晶体的制备更有着深远的意义。理论计算表明C₆₀/AlN、C₆₀/GaN、C₇₀/AlN、C₆₀薄膜和二氧化硅包覆碳球（CSs）在紫外、可见以及近红外光区存在光子带隙,这预示了洋葱状富勒烯（OLFs）、碳球类碳材料在光子晶体领域具有潜在的应用前景。本文围绕构成碳基光子晶体结构单元即OLFs类碳材料的低成本制备、表面修饰和在聚合物基体中的分散进行展开,为进一步探索其作为碳光子晶体材料的应用提供重要的基础性实验准备。主要取得了以下几方面的结果:（1）采用CVD法,以Fe/Al（OH）₃和Fe/NaCl为催化剂低温（400℃）制备了OLFs。首先,考察了温度对Fe/Al（OH）₃催化CVD法产物结构与形貌的影响,结果表明低温400℃有利于OLFs的生长,产物为纯度高的内包Fe₃C的OLFs,对其进行真空热处理得到了纯度高、石墨化程度较高、直径分布在15-60nm之间的OLFs。其次考察了催化剂活性组分Fe的含量对Fe/NaCl催化CVD法产物结构与形貌的影响,结果表明低的Fe负载量有利于合成纯度高的OLFs,当Fe负载量为0.3wt%时,合成了直径在15-50nm的OLFs,对其进行真空热处理得到了纯度高、石墨化程度较高、直径分布在15-50nm之间的OLFs。由于载体NaCl仅通过水溶就可以将其从产物中去除,因此Fe/NaCl催化CVD法是低成本制备高纯度OLFs的有效方法。在实验结果的基础上,提出了内包碳化铁OLFs生长机理—VS生长模型:碳源气体C2H2在催化剂颗粒（纳米Fe颗粒）吸附、分解,分解和初步缩聚出的碳原子簇在催化剂晶格间的扩散、析出、重组成层状堆积结构排列的石墨片层。由于反应温度较低,在催化剂晶格间扩散的碳原子不能完全析出,便与Fe形成碳化铁,被已经形成的石墨片层所包裹,最终形成内包碳化铁的石墨化程度不高的OLFs。（2）以CSs为模板核,以正硅酸乙酯为二氧化硅的前驱体,通过溶胶-凝胶法在CSs表面包覆SiO₂得到了CSs-SiO₂核-壳结构的复合物球,实现了CSs表面的包覆改性。然后经过高温焙烧除去复合物球中的CSs核得到空心二氧化硅球。首先考察了包覆时的介质条件对包覆效果的影响,发现碱性介质有利于在CSs表面包覆二氧化硅,得到的复合物球表面光滑,包覆层厚且厚度均一。通过改变前驱体TEOS的用量和反应时间可控制包覆层的厚度,即空心SiO₂球壳层的厚度。CSs表面包覆SiO₂后热稳定性提高。在实验基础上,提出了CSs-SiO₂核-壳结构和空心SiO₂球可能的形成机理—静电作用机理。阳离子表面活性剂CTAB改性的CSs表面带正电荷通过静电引力吸附实验pH下带负电荷的TEOS水解产物SiOH,沉积在CSs核表面的SiOH缩合形成结构致密的SiO₂包覆层,得到核壳结构复合物球。焙烧除去CSs核后,得到空心SiO₂球。（3）采用HNO₃/H2O2、HNO₃和HNO₃/H2SO4等多种氧化剂对CSs进行氧化改性,系统研究了氧化剂的配比、浓度和氧化时间对CSs结构形貌、引入的官能团的种类和数量的影响,并考察了不同氧化条件处理的CSs在水中的分散性能。以HNO₃/H2O2混合溶液为氧化剂时,氧化时间和体积比相同条件下,随HNO₃、H2O2浓度的增加,引入的-COOH、-C-OH和-C=O等含氧官能团的量增加;当浓度不变时,CSs表面-COOH、-C-OH和-C=O等含氧官能团的含量随HNO₃和H2O2体积比的变化而变化。采用体积比为1︰1的浓HNO₃/H2O2处理时,氧化改性的效果最好,引入的含氧官能团最多,氧化后的CSs表面-COOH、-C-OH、-C=O和含氧官能团的总量分别为0.2614mmol/g、1.105mmol/g、0.7976mmol/g和2.164mmol/g。以HNO₃为氧化剂时,随HNO₃浓度的增加和氧化时间的延长,引入的-COOH、-C-OH和-C=O等含氧官能团的含量增加,浓HNO₃处理1h的改性效果最好,引入的含氧官能团最多,-COOH、-C-OH、-C=O和含氧官能团的总量分别为0.8080mmol/g、3.021mmol/g、1.047mmol/g和4.876mmol/g。以混酸为氧化剂时,相同温度下,随处理时间的延长,-COOH、-C-OH和-C=O等含氧官能团的量增加。混酸处理1h的碳球表面-COOH、-C-OH和-C=O的含量分别为0.5080mmol/g、3.510mmol/g和0.3790mmol/g,含氧官能团的总量为4.379mmol/g。三种氧化体系相比较,混酸氧化改性的效率最高,接着依次是浓HNO₃和HNO₃/H2O2。氧化后CSs表面的亲水性和在水中的分散性明显改善,不同氧化条件下引入的官能团的种类和数量不同,因此可以通过改变氧化条件来控制CSs表面官能团的种类和数量。（4）利用氧化改性后CSs表面的-COOH、-C-OH与丙烯胺或丙烯酰氯反应均可在CSs表面引入乙烯基基团。将乙烯基功能化碳球直接加入甲基丙烯酸甲酯（MMA）单体,通过原位聚合法得到了CSs均匀分散、与聚合物相容性好的复合材料。将氧化改性的CSs用NaOH处理使其离子化后,与可聚合表面活性剂十八烷基二甲基苄基苯乙烯氯化铵（VODAC）一起加入MMA中,通过原位聚合法得到了CSs均匀分散的复合材料。将离子化CSs与VODAC一起加入水中分散均匀后,再加入MMA或苯乙烯（St）萃取,萃取结束后取出油相再原位聚合-萃取聚合法,结果表明在聚甲基丙烯酸甲酯基体中,碳球分散性和与基体的相容性均很好;在聚苯乙烯基体中碳球分散性很好,但与基体的相容性略差一些。更多还原

【Abstract】 Photonic crystals are a periodical materials which are fabricated by periodically arranging two materials having different dielectric constants. Photonic bandgap is one of the basic characters of photonic crystals, which controls the propagation of light and thus casts the basis for optical devices and communication component. Non-close-packed structured photonic crystals possess a widened bandgap and are easy to form complete photonic bandgap, thus investigating the preparation of non-close-packed structured photonic crystals holds far-reaching meaning. Theoretical calculations showed that C₆₀/AlN, C₆₀/GaN, C₇₀/AlN, C₆₀ films and carbon spheres coated by silica possess photonic bandgap in UV, visible and near-infrared region, which indicates the potential applications of onion-like fullerenes （OLFs） and carbon spheres （CSs） in the field of photonic crystals. Bases on this research background, this thesis has focused on the low-cost preparation, surface modification of onion-like fullerenes carbon materals and the dispersion of these materials in polymer matrix. The conclusions are listed as follows: （1） OLFs were synthesized at low-temperature （400℃） by chemical vapor deposition （CVD） using Fe/Al（OH）₃ and Fe/NaCl as catalysts. Firstly, the influences of reaction temperature were investigated, with respect to the structure and morphology of the product using Fe/Al（OH）₃. as catalyst The results show that low-temperature of 400℃was in favor of the growth of OLFs, the product are composed of OLFs encapsulating Fe₃C. OLFs with high-purity, high degree of graphitization and size of about 15-60nm were obtained after the heat treatment in vacuum. Secondly, the influences of Fe/NaCl with different Fe content were investigated, with respect to the structure and morphology of the product using Fe/NaCl as catalyst. The results show that low Fe content was in favor of the growth of OLFs. OLFs encapsulating Fe₃C with size in the range of 15-50nm were prepared using catalyst containing 0.3wt% Fe. OLFs with high-purity, high degree of graphitization and size of about 15-50nm were obtained after the heat treatment in vacuum. Because the support NaCl could be removed by water washing, high purity OLFs synthesis using Fe/NaCl as catalysts by CVD method is a low-cost efficient route. Based on the experimental results, the growth mechanism of OLFs encapsulating Fe₃C was suggested: gaseous carbon species derived from C2H2 are absorbed and decomposed on the surface of catalyst particles, carbon atom clusters diffuse between crystal lattice of catalyst, precipitate and recombine into graphitic layers. The incomplete precipitation of carbon atoms between crystal lattice of catalyst led to their reaction with Fe and formation of Fe₃C, Fe₃C were encapsulated by graphitic layers, finally OLFs encapsulating Fe3C with the low degree of graphitization were obtained.（2） CSs-silica core-shell structured material was prepared using tetraethyl orthosilicate（TEOS） as precursor of silica by a sol-gel method. Carbon sphere （CSs） cores were prepared by the pyrolysis of acetylene. After CSs cores were removed by calcinations, hollow silica spheres were obtained. Firstly, the influences of the coating medium were investigated. CSs were easy to be coated with silica in basic medium, which produced the compositie spheres with smooth surface and uniform shell thickness. The coating thickness, which is also the shell thickness of the hollow spheres, could be controlled by changing the volumes of TEOS and reaction time. The thermal stability of CSs was improved after silica coating on the surface of CSs. The formation of the core-shell structure was suggested to follow electrostatic interation mechanisam. The surfaces of CSs modified by cationic surfactant cetyltrimethylammonium bromide（CTAB） were characterized by positive charges, and absorbed negatively charged silicon hydroxide species originated from the hydrolysis of TEOS via electrostatic interaction, which provided nucleation sites of silicon hydroxide species on the surface of carbon spheres. And the core-shell structure was formed. The hollow silica spheres were obtained when carbon spheres were removed by calcinating in air.（3） HNO₃/H2O2, HNO₃ and HNO₃/H2SO4 were used as oxidant to modify the carbon spheres surface. The influences of the proportion, concentration and treatment time of the oxidant on the morphology of CSs, the type and amount of the functional groups introduced on the surface of CSs were studied. The dispersion of the oxidized CSs in water was analyzed. When HNO₃/H2O2 was used as oxidant, as HNO₃ and H₂O₂ solution concentration increased, the amount of carboxyl, hydroxyl, carbonyl,and total oxygen-containing functional groups（TOFGs） increased. The amount of carboxyl, hydroxyl, carbonyl, and TOFGs changed with the changing the volume ratio of HNO₃ and H₂O₂. The modification effect was best when CSs were treated by the volume ratio 1:1 of HNO₃ and H2O2, which introduced 0.2614 mmol/g of carboxyl, 1.105mmol/g of hydroxyl, 0.7976mmol/g carbonyl and 2.164 mmol/g of TOFGs onto the surface of CSs. When HNO₃ was used as oxidant, the amount of carboxyl, carbonyl, hydroxyl and TOFGs increased with increasing HNO₃ solution concentration and treatment time, the treatment by concentrated nitric acid for 1h introduced 0.808 mmol/g, 3.021mmol/g of hydroxyl, 1.047mmol/g carboxyl and 4.876mmol/g of TOFGs onto the surface of CSs, which were the maximum value. When HNO₃/H2SO4 was used as oxidant, the amount of the functional groups increased with prolonging treatment time. The treatment by HNO₃/H2SO4 for 1h introduced 0.508mmol/g of carboxyl, 3.51mmol/g of hydroxyl, 0.379mmol/g of carbonyl and 4.379mmol/g of TOFGs onto the surface of CSs. Among the three oxidation systems, the oxidation efficiency of HNO₃/H2SO4 was the highest, followed by HNO₃ and HNO₃/H2O2. The hydrophilicity and dispersion in water of oxidized CSs were improved distinctly. The type and amount of the functional groups introduced on the surface of the carbon spheres were different after different treatment. So the type and amount of the functional groups on the surface of CSs could be controlled by changing oxidation condition.（4） Vinyl groups were introduced on the surface of CSs by carboxyl, hydroxyl functional groups reacting with allylamine or chloromethylstyrene. Vinyl-functional CSs were added directly into methyl methacrylate（MMA） monomer, composite materials containing CSs dispersed uniformly in polymethylmethacrylate（PMMA） matix with good compatibility with polymer were obtained via in-situ polymerization. The oxidized CSs were ionized after the treatment by NaOH. Ionized CSs and polymerizable surfactants octadecyl-p-vinylbenzyl-dimethylammonium chloride （VODAC） were added into MMA. Composite materials containing CSs dispersed uniformly in PMMA matix were obtained. Ionized CSs and VODAC were added into water and dispersed uniformly. And then MMA or styrene（St） was added into the above suspension. Oil phase was taken out after extraction and polymerized. Field emission scanning electron microscopy observation shows that CSs were well dispersed in PMMA matix and had good compatibility with polymer; CSs were well dispersed in polystyrene matix, but the compatibility with polymer was not as good as PMMA.更多还原