【作者】 付建伟；

【导师】 唐小真；

【作者基本信息】 上海交通大学 ， 材料学， 2009， 博士

【摘要】 本论文基于膦腈化学合成的特性,从介观尺度自组装的角度,建立了一种模板诱导自组装理论（组装基元为纳米粒子,基元间的连接为化学键连接）,不同于常规的分子尺度自组装（组装基元为小分子或大分子,分子间的作用为非化学键连接）。一方面,提供一种新型的制备一维聚合物纳米材料的方法,拓展介观尺度自组装的研究内容;另一方面,借助纳米技术,探索环交联型聚膦腈纳米材料在高端技术领域内的应用。具体研究内容及结果如下:（1）在以六氯环三膦腈（HCCP）与4,4′-二羟基二苯砜（BPS）作为共聚单体,三乙胺（TEA）作为缚酸剂,丙酮为溶剂的反应体系中,分别考察了温度、超声功率、单体浓度和投料方式对产物形貌的影响,进而优化出聚膦腈（PZS）纳米纤维的制备方案。在优化方案条件下,借助SEM、TEM等手段,通过追踪PZS纳米纤维的演变过程,建议了一种PZS纳米纤维的形成机理——原位模板诱导自组装,依据此机理制备出了直径在40～60 nm,长度数微米,初始热分解温度达444℃的PZS纳米纤维,制备过程可在室温条件下、10 min内完成。（2）基于提出的原位模板诱导自组装机理,可控的制备出了多形PZS纳米管（辣椒状、支化状及均匀管）及功能化纳米管,这些PZS纳米管具有高度交联的化学结构,N₂吸附试验表明该类型纳米管的壁面上有微孔及介孔的存在,这种独特的结构使其有望作为药物载体材料、吸附剂材料及纳米反应器。另外,通过改变溶剂极性或超声条件,可实现产物形貌从纳米管到微球的渐变过程。（3）以所制备的聚膦腈微纳米材料为前驱体,通过高温碳化实现了多孔碳球、碳纳米纤维和碳纳米管的制备,探索出了一条新的制备碳微纳米材料的路径。碳材料的比表面积和孔容的大小可通过调节碳化温度或高温条件下的保温时间来控制,微孔直径分布在0.5～1nm之间,微孔的形成是PZS在碳化过程中非碳组分逸出造成的。（4）基于外加模板诱导自组装机理,我们制备了一种Ag/PZS同轴纳米电缆,所制备的同轴电缆有如下特点:由于采用了一种高稳定性的交联聚膦腈为同轴纳米电缆的壳层材料,其在空气中的热分解温度为440℃,远高于常规的线形聚合物壳层材料的热分解温度,因而,以交联聚膦腈作为壳层材料,可实现对金属纳米线更好的保护;通过调节共聚单体和Ag纳米线的摩尔比,本纳米同轴电缆的壳层材料厚度可在80～300nm之间调控,从而满足不同场合对同轴纳米电缆的要求;本方案所涉及的Ag/PZS同轴纳米电缆的制备过程由于是在室温下完成,无需表面活性剂或保护剂,因而工艺简单,易于控制并可节约能源。（5）基于外加模板诱导自组装机理,我们用聚膦腈对多壁碳纳米管（CNTs）进行了改性,就改性过程而言,本方法有如下优点:PZS功能化的碳纳米管可轻易的溶解于水及大部分有机溶剂中（如DMF、丙酮、THF、乙醇等）;PZS在CNTs表面的非共价键包覆过程是借助外加模板诱导自组装机理而非传统的π-π相互机理;PZS在CNTs表面的包覆过程是室温条件下一步完成的,没有使用任何表面活性剂或协同剂,简化了后处理程序,并且包覆层的厚度是可控的。（6）以HCCP与BPS为共聚单体,TEA为缚酸剂,室温条件下成功制备了以Si纳米球为核、PZS为壳的纳米复合微球,TEM表征显示该PZS层的厚度在5～10 nm。该复合微球经900℃的高温碳化后,形成了Si@C纳米复合材料,该材料可作为锂离子电池的负极材料,显示出较高的比容量（1200 mAh/g）、较高的首次充放电效率（73.8%）和良好的循环稳定性。更多还原

【Abstract】 In this paper, based on the characteristic of phosphazene chemistry, a new template induced self-assembly mechanism (building unit is nanoparticle and the connection between units is chemical bond) was suggested from the view of meso-scale point, different from the normal molecular scale self-assembly (building unit is molecule or macromolecule and the connection between units is nonchemical bond). On the one hand, to provide a novel method to preparing one dimensional polymer nanomaterials, widening the research area of meso-scale assembly field; on the other hand, with the help of nanotechnology, to explore the application of cyclomatrix-type poly phosphazene nanomaterials in high-tech fields. Special research content and results are as follows.In the reaction system with hexachlorocyclotriphosphazene (HCCP) and 4,4’-sulfonyldiphenlo (BPS) as comonomers, triethylamine (TEA) as acid-acceptor, and acetone as solvent, an optimum condition for preparing poly(cyclotriphosphazene -co-4,4’-sulfonyldiphonel) (PZS) nanofibers was obtained through checking the influence of different conditions such as temperature, ultrasonic power, monomer concentration, and feeding methods on the morphology of as-synthesized product. Under the optimum condition, with the help of SEM and TEM, we tracked the evolution process of PZS nanofibers and suggested a formation mechanism of nanofibers—in situ template induced self-assembly. Based on this mechanism, we obtained PZS nanofibers with diameter of 40～60 nm, length of several micrometers and initial thermal decomposition temperature of 444°C, which could be prepared in ten minutes under room temperature.Based on the proposed mechanism of in situ template induced self-assembly, polymorphic PZS nanotubes (capsicum-like, uniform and branched) and functionalized PZS nanotubes were prepared separately. All these nanotubes owned a highly cross-linked chemical structure. Results of nitrogen adsorption test showed that the surface of as-synthesized nanotubes possessed micro- and mesopores. The unique structure is expected to make them as drug carriers, adsorption materials and nanoreactors. In addition, the morphology change of as-synthesized product could be realized from nanotubes to microspheres by changing the polarity of reaction solvent or ultrasonic power.Taking the PZS micro- and nanomaterials as precursors, a new road to carbon materials including porous carbon spheres, carbon nanotubes and nanofibers was developed through high temperature carbonization. The specific surface area and pore volume of carbon materials could be controlled by adjusting the size of carbonization temperature or keeping time under high temperature. Characterization results showed that the pore diameter distribution of the carbon materials was centered at 0.5～1 nm and their formation originated from the escaped non-carbon elements.Based on the external template induced self-assembly mechanism, Ag/PZS (core/shell) coaxial nanocables were prepared, which had typical characteristics as follows: (1) the shell materials possess highly stable cross-linked structure with 440°C of initial thermal decomposition temperature, much higher than that of the normal linear polymer for shell materials, and thus cross-linked PZS as shell layer could better protect the metal nanowires as core layer; (2) the shell thickness of nanocalbes could be adjusted from 80 to 300 nm through changing the molar ratio of comonomers to silver nanowires, meeting the needs of different occasions on the coaxial nanocables; and (3) the preparation of Ag/PZS nanocables was performed without use of any surfactants or protective agents at room temperature, which process was simple, easy to control and reduce energy consumption.On the basis of the external template induced self-assembly mechanism, multi-wall carbon nanotubes (MWCNTs) were modified by polyphosphazenes successfully. As for the modification process, this method had the following advantages: (1) the PZS-functionalized carbon nanotubes could be easily dissolved in water and most organic solvents such as DMF, acetone, THF, and ethanol, (2) the non-covalent wrapping process of PZS on the carbon nanotubes was based on the external template induced self-assembly mechanism, rather than the conventional n-n interaction, (3) the wrapping process could be performed in one pot at room temperature, without using any surfactants or synergists, and thus the post-processing was simplified, and (4) the wrapping layer thickness on the MWCNTs could be controlled.Si@PZS composite nanospheres with 5～10 run shell (PZS) thickness were prepared successfully using HCCP and BPS as comonomers, and TEA as acid-acceptor at room temperature. After carbonization of the composite nanospheres at 900°C , Si@C nanocomposites with porous carbon layer were obtained. The electrochemical measurements showed that the carbonization samples exhibited a high specific capacity of 1200 mAh/g, a high first charge-discharge efficiency of 73.8%, and an excellent cycling stability. The superior electrochemical performance makes the Si@C nanocomposite as a promising cathode material for lithium-ion batteries.更多还原