【作者】 时宜；

【导师】 唐颐； 张亚红；

【作者基本信息】 复旦大学 ， 物理化学， 2011， 博士

【摘要】 自上世纪90年代纳米材料真正诞生以来,其成核、结晶、定向生长、稳定、组装和应用一直是众多自然科学范畴,如物理学、化学、材料学和生物医学等的研究热点。在各领域中,结构新颖、功能优越的各种纳米尺度和纳米结构材料展示了其优于块体材料的优良性能,具有广阔的市场和开发前景。其中,聚合物诱导下无机纳米的组装和晶化过程一直为科学界所关注。通过设计和考察聚合物在无机纳米材料组装和晶化中的作用机制,可制备不同结构和性能的组装体材料。该类型材料一方面保留有纳米材料本身的特性,如大外表面积、丰富的外表结构和活性位点；另一方面其较大的尺寸和可调节的组装过程,使得作为纳米材料的组装体,可以解决纳米尺度材料在特定应用领域的难以操控的不足。然而,目前由于各种组装方法的固有缺陷、方法种类有限、应用层面考虑不足和对合成和晶化过程的研究、生长机理不明确等一系列问题的存在,加之对于如何控制和设计组装过程和组装体,如何充分体现在相关应用领域的优势仍然存在空白,这些问题严重限制了无机物纳米材料的发展和应用开发。因此,通过设计聚合物的结构或其聚合过程,合成和研究聚合物诱导下无机纳米材料的组装和晶化过程,获得一定形貌和结构的组装体,探索或深化对聚合物结构和聚合过程的研究,对设计和开发更多特殊功能的纳米材料、提供更多的选择范围和对材料设计思想具有深远意义。本论文工作以“聚合诱导下无机纳米材料组装和晶化过程”为主线,针对上述所存在的一系列问题,从“聚合物结构、聚合过程设计和控制”、“无机纳米组装体的结构调控和形成机理研究”和“无机纳米材料的功能开发”三方面入手。采用未经过任何处理的纳米沸石合成原液,研究了改进的聚合诱导胶体凝聚中的脲醛树脂聚合过程,通过对微球形成规律的细致考察,调控了沸石微球组装体的合成过程；通过对合成条件的精确调控和对沸石微球结构和纳米沸石表面性能的研究,提出了新的“聚合速度匹配”组装机理；进一步通过对聚合过程的不断认识和深化,发现其聚合过程中不同结构的特点和性能,合成了不同表面结构和种类的微球材料；并通过四个不同的催化反应过程具体考察了沸石微球的优良性能。另外,通过对聚天冬氮酸分子结构的设计和合成,考察了磷酸钙的溶液相组装过程；进一步引入壳聚糖为界面高分子识别基底,考察了界面相磷酸钙的晶化过程,探索了聚天冬氨酸诱导下的晶化过程机理。在上述工作中,即拓展了材料的合成方法和新结构,又丰富了现有的合成理论和机理,这些材料在催化以及生物材料中都表现出突出的性能,为设计和合成新结构和功能的纳米材料提供新的思路。本论文针对上述研究工作分七个章节进行讨论：第三章讨论了聚合诱导胶体凝聚法制备β沸石微球。首次应用纳米沸石合成原液一步法合成沸石微球,其中的纳米沸石未经过任何处理、方法过程简单、操作便捷、成本低廉、具有量产的前景。通过对产品结构的系列表征可发现,随着酸加入量的不同,可以得到不同形貌和结构的纳米沸石组装体。在此过程中酸度的控制是至关重要的因素,经由zeta电势的变化可以指示该过程,通过“聚合速度匹配”组装机理可以解释其组装过程。该方法合成的β沸石微球,由于具有纳米沸石的己有属性,加之方法特有的堆积介孔特征,使之在催化领域,特别是受扩散控制的反应、副反应较多的反应、低温反应和大分子反应等的应用中具有广阔的前景。第四章研究了聚合诱导胶体凝聚法的体系拓展。首先采用不同硅铝比和不同结构的纳米沸石合成原液,考察了在此体系下的响应情况。通过系列的实验和结构表征进一步验证了“聚合速度匹配”机理。进而通过对合成体系的方法拓展,如通过碱性体系下脲醛树脂保护的方法,可以得到不同粒径和结构的去除模板剂的单分散纳米沸石；通过酸性体系下脲醛树脂浇筑的方法可以得到大孔/微孔复合沸石块体材料；在合成体系中引入金属盐溶液,可制备出沸石-金属复合微球材料。第五章介绍了沸石微球在催化反应中的应用。采用四个反应：(反应一)动态动力学拆分反应(液相低温反应)；(反应二)果糖脱水合成羟甲基糠醛(液相低温反应)；(反应三)碳四烯烃裂解反应(气相高温反应)；和(反应四)丁烷丁烯的烷基化反应(气相低温反应)来表征沸石微球的独特优势。沸石微球保留有纳米沸石的大外表面、短孔道、活性位易达易离等特点,使得其反应物和产物的扩散限制大大降低,反应物快速接触活性位和产物快速脱离活性位,积炭过程缓慢,容炭能力强,催化剂寿命提高,而纳米沸石间的独特堆积介孔更有利于此过程。通过不同反应和条件表明,沸石微球催化剂与商品沸石相比有着更好的催化效果,优势明显。第六章阐述了聚天冬氨酸和壳聚糖诱导下磷酸钙的溶液相和界面相晶化过程。通过设计合成不同电荷密度的聚天冬氨酸,研究了其诱导下的溶液相磷酸钙纳米片层晶化组装过程,系统考察了不同条件下组装体的结构和表面性能,通过对晶化过程中的反应物浓度、温度、响应时间、有机物含量等的考察,成功的捕捉和观测了整个晶化过程,提出了两个相互竞争的反应过程,并验证了经典的聚合物诱导晶化组装机理。进一步通过荷正电荷的高分子-壳聚糖将晶化过程引入到界面相,研究了在两种聚合物共同诱导下磷酸钙的结晶过程,并考察了其形貌和结构的变化规律,发现了溶液和界面的竞争晶化过程。通过界面相过程所得到的不同结构的磷酸钙膜层在细胞黏附和增殖的生物相容性测试中得到不同的响应效果。综上所述,以“聚合物诱导下无机纳米材料组装和晶化”为主线,通过调控聚合物的聚合过程和电荷密度,研究了无机纳米组装体结构变化,合成了系列不同的组装体材料,研究了聚合物在组装和晶化过程中的作用并提出了“聚合速度匹配”组装机理、发现了两个相互竞争的晶化反应和溶液相界面相之间相互竞争的晶化过程。同时,研究了沸石微球材料在动态动力学拆分反应、果糖催化分解、碳四烯烃裂解和烷基化反应中的应用等。通过对聚合物在纳米材料的组装和晶化过程的研究和形成机理的阐述,为新材料开发与设计和催化反应的应用提供了借鉴和启发意义。更多还原

【Abstract】 Since the birth of nanomaterial in the last 90s, lots of attention has been paid to its nucleation, crystallization, oriented growth, stability, assembly and applied into a number of areas, such as physics, chemistry, materials and biomedical science. In various fields, compared with bulk materials, nanoscale and nanostructured materials with new structure and superior functional properties have demonstrated theri excellent performance, and have a vast market and prospects. Among them, much concern has been paied to the polymer induced inorganic nanoscale assembly and crystallization process. Nanomaterials with different structures and properties can be prepared when familiar with the design and assembly procedure. The nanoscale and nanostructured materials on the one hand retain the characteristics of their parent nanoparticles, such as large external surface, rich structural properties and active sites, and on the other hand, can solve control deficiency and bring convenient in the specific application field because of their large size and adjustable assembly process.However, there are still lots of gaps due to a range of issues, such as the inherent defects for various assembly methods, lack consideration for application, insufficient understanding to the synthesis process, and vague crystallization mechanism. Together with little know about how to fully embody the advantages, these problems have severely impeded the further development into related areas. Thus, it will be meaningful to deepen polymerization process and obtain the nanoscale assembly with a certain shape and structure of polymer. Due to aspiring significance, this will favor for the design and provide more choice of nanomaterials with outstanding specific features.This thesis is focus on "polymer induced nanoscale assembly, nanostructure transformation and crystallization". Based on this, three aspects have been put forward, i.e. "design and control of polymer structure and polymerization", "nanoscale assembly and its formation mechanism" and "functional inorganic nanomaterials". In detail, nanozeolite colloidal solution without any further purification and treatment has been used in the improved polymerization induced colloid aggregation (im-PICA). Through a full study of the reaction conditions and nanosurface properties, precise control and regulation have been paid into the urea-formaldehyde resin polymerization process. The morphology and composition of poducts were finely controlled through simply adjusting the acidity of the polymeric system. A polymerization-velocity-match (PVM) mechanism was proposed to explain the morphology variation of the samples under different polymerization conditions. Owing to their stacking secondary pores and large external surface inherited from nanozeolite, the as-prepared zeolite microspheres (ZMSs) displayed an improved catalytic performance to various catalysis reactions. Moreover, induced by polyaspartic acid with a changing charge density on its molecular structure, the assembly and crystallization process of calcium phosphate have been investigated in the solution. And combining with positive charged chitosan as matrix, further study has been paid to the interfacial deposition process. The above researches extend the synthesis methodology of nanoscale and nanostructured materials, and also enrich the existing theory and mechanism. All of these lighten the new structure materials with outstanding performance for catalytic and biological appication. The dissertation will be divided and discussed into seven chapters:Chapter III discussed the preparation of P-ZMS using im-PICA. It is the first time that using nanozeolite colloid solution just after hydrothermal process without any treatment in PICA method,β-60 was taken as the typical nano-unit in the one-step assembly and synthesis procedure. The method is a simple and convenient to attain ZMSs with a prospect of low cost and large scale. By the variation of components, ZMS with different morphologies and structures can be assemblied, and acidity in this synthetic system is viewed as a crucial control element. Through the probe to the changes of zeta potential, it may indicate how/what will take place in polymerrization process. And PVM mechanism can explain the assembly process and structure transformation. Retained with properties of nanozeolites and inherited mesopores after removing UF polymer, ZMS may show broad prospects in catalysis particularly in the reaction controlled by diffusion, interfered largely by side-reactions, and taken at low temperature.Chapter IV investigated the im-PICA assembly process further using nanozeolite with different Si/Al2 ratios and structures. Inspite of changes of the synthetic condition and nanosurface properties, the morphologies and structures evolution confirmed the correctness of PVM mechanism. Also, through the control of polymerization process, urea formaldehyde resin protecting (UFP) method can be used to synthesis template-free mono-dispersed nanozeolite with different sizes and structures. Using urea formaldehyde resin moulding (UFM) method can acquire zeolite monolith with macropores and micropores. Furthermore, combined with metal salts in the synthetic system, metal@ZMS can be prepared simply.ChapterⅤstudied four useful reactions catalyzed by ZMS. The two of them are liquid phase reactions under low-temperature, i.e. dynamic kinetic resolution and fructose dehydration into 5-hydroxymethyl furfural. The other two are gas phase reactions, i.e. C4-olefin cracking at high temperature and alkylation at low temperature. Compared to commercial zeolite, ZMS maintains unique advantages such as the retained larger external surface, short channel, accessible active sites, and characteristic mesopores. So, reactants and products have little diffusion limit, quick access and escape from the active sites. Thereby, due to slow carbon deposition and larger carbon capacity, catalyst life will increase. And based on the probe to the four different reactions at various conditions, ZMS catalyst showed a better catalytic effect than commercial zeolite.ChapterⅥdescribed polymer induced mesoscale assembly and transformation process for calcium phosphate crystallization. Firstly, polyaspartic acid with different charged density was used to study the assembly process in solution. The system with different conditions was applied to investigate the morphology and structure evolution, such as concentration, temperature, induction time, and organic compound content. Also, the successful capture and observation of the detailed process elucidated two competing reactions existing in the crystallization and further verified the classic "polymer induced mesoscale transformation". Moreover, through positive charged polymer matrix-chitosan, the crystallization process was introduced to interface. Induced by the two kinds of polymers, morphology and structure changes were investigated, and the competitive crystallization between solution and interface was put forward. The as-synthesized calcium phosphate membranes with different structures showed different response in the cell adhesion and proliferation in biocompatibility test.In summary, polymer induced nanoscale assembly and nanostructured crystallization were studied through the regulation of the charge density of polymer and polymerization process. Various inorganic materials with different nanoscales and nanostructures were attained and their polymer induced assembly crystallization was dicussed in elaboration. Through the proposed "polymerization-velocity-match" mechanism can explain the whole assembly procedure and structure variation. The two competing reactions and crystallization between solution and interface reaction further illustrated the mesoscale transformation. Besides the novel nanostructures with functional properties, several mechanism and synthetic strategies have been proposed in this work, which will open up opportunities for the synthesis and design of new nanomaterials and provide a reference and instructive sight for catalytic reactions.更多还原