【作者】 王锋伟；

【导师】 张兴元； 刘华蓉；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2014， 博士

【摘要】 具有特殊功能和形貌的微球近年来受到了广泛的关注,我们因此研究了制备功能性各向异性和中空微球的新方法。通过改变反应条件来调控它们的形貌和性能,研究了各向异性粒子作为粒乳化剂在稳定乳液及制备多层次结构材料的应用,中空微球作为载体在医药和催化领域的应用。本论文的主要研究内容如下：1.发展了一种由γ射线引发的种子乳液聚合制备雪人球型磁性/非磁性各向异性纳米复合粒子的方法。通过在无皂乳液聚合制备的聚(苯乙烯-二乙烯苯-丙烯酸)(P(St-DVB-AA))微球表面原位生成磁性四氧化三铁粒子,形成了树莓状的磁性纳米复合粒子(RMNPs)；以RMNPs为种子,通过γ射线辐射引发第二单体的种子乳液聚合,获得雪人型各向异性纳米复合粒子。我们研究了表面活性剂的种类、第二单体的种类及用量、溶胀剂的用量等对最终纳米复合粒子形貌的影响,发现当使用可聚合的Y型小分子12-丙烯酰氧-9-油酸(AOA)作为乳化剂,以苯乙烯为第二单体,添加溶胀剂2-丁酮的情况下,可以制备出典型的雪人型磁性/非磁性各向异性纳米复合粒子(SMNAPs).所制备的SMNAPs容易吸附在油水界面上,能够作为外界磁场可控的颗粒乳化剂来稳定水油混合溶液。2.蠕虫状P(St-AA)@Fe3O4/SiO2磁性复合粒子的合成：利用无皂乳液聚合及原位化学沉淀法成功制备了头部为超顺磁性的P(St-AA)@Fe3O4复合粒子；并以CTAB为模板,通过溶胶-凝胶法在复合粒子的一端形成蠕虫状的二氧化硅。我们研究了CTAB浓度、TEOS量、氨水的量、前驱体的组成以及乳化剂的组成等对最终P(St-AA)@Fe3O4/SiO2复合粒子形貌的影响。值得一提的是,虽然所得蠕虫状复合粒子整体都呈现出相对亲水的性质,但由于头和身体部分两亲性的差异以及这种粒子的特殊形貌,它们仍能作为颗粒乳化剂来稳定油水混合溶液,这点与球形均一粒子不同。这种蠕虫型颗粒乳化剂为Pickering乳液的稳定以及构建多层次结构材料提供了一种新的途径。3.利用先溶胀种子微球再包覆无机壳层,最后进行辐射种子乳液聚合的方法,制备了具有两亲性的雪人型P(St-DVB-AA)@SiO2/P(St-DVB)粒子。我们研究了第二单体及无机前驱体的用量和种类、不同的辐射聚合条件(剂量率及吸收剂量)等因素对所得复合粒子形貌的影响。这种各向异性粒子可以用作理想的颗粒乳化剂来稳定油包水型的乳液；在此基础上,进一步辐射聚合水相或者油相中的单体之后,就可以得到无皂的多层次结构微球或块状材料。4.描述了在同一体系中,利用水解缩合与辐射种子乳液聚合相结合的方法来制备多种形貌(树莓型、多头、三角型和雪人型等)的P(St-DVB-AA)/P(MPS-St)复合粒子。通过简单地改变加入的第二单体或者无机前驱体的量,就能达到控制复合粒子形貌的目的。所得的树莓型复合粒子制成颗粒膜并进行疏水改性后,可以使接触角提高到146°。同时,所得雪人型复合粒子可以用作颗粒乳化剂来稳定油水混合液；并且在聚合油相后,可以得到多层次结构多孔块状材料。我们也尝试了这种无皂多孔块状材料在污水处理方面的简单应用。5.研究了一种制备Fe3O4@m-SiO2磁性中空微球的简单方法。以树莓型P(St-AA)@Fe3O4粒子为种子,通过溶胶-凝胶法形成介孔SiO2壳层,同时聚合物核在高浓度氨水乙醇溶液中可被溶解掉,从而一步获得Fe3O4@m-SiO2磁性中空微球,免去了移除内核模板的步骤。我们研究了氨水、CTAB、TEOS的加入量,溶剂的组成和溶胶凝胶反应时间对最终产物结构的影响,并初步探索了这种磁性中空介孔微球的药物释放效果。6.利用乳液作为界面聚合的模板,发展了一种简易的可大规模制备壳层可控的中空沸石咪唑酯框架材料(ZIF-8)微球的方法。另外,贵金属纳米粒子(NMNPs,如Pd)可以在乳化阶段加入,从而作为催化反应的活性中心。由于外层的ZIF-8具有固定尺寸的晶体孔道以及可调控的整体结构,使得Pd@ZIF-8成为α-β不饱和醛选择性加氢反应中的一种非常有前景的催化材料。更多还原

【Abstract】 Recently, microspheres with special functions or morphologies have gained increased attentions. In this thesis, we developed new approaches for the fabrication of anisotropic and hollow microspheres. Their properties and structures were tuned by adjusting the reaction conditions. Anisotropic microspheres were applied as solid surfactants to stabilize emulsions and then to construct hierarchical materials via radiation emulsion polymerization, while hollow microspheres were used as carriers in the field of drug delivery and catalysis. Detailed contents in this thesis were shown as follows:1. We described the synthesis of snowman-like magnetic/none-magnetic nanocomposite asymmetric particles (SMNAPs) via seeded emulsion polymerization initiated by y-ray radiation. In-situ formation of magnetite in the presence of the emulsified poly(styrene-divinylbenzene-acrylic acid)[P(St-DVB-AA)] microspheres affords raspberry-like magnetic nanocomposite particles (RMNPs), which are used as seeds for further seeded emulsion polymerization induced by y-ray radiation. We study the effect of the kind of surfactant, the kind and content of second monomer, and the content of swelling agent on the morphologies of the final nanocomposite particles. It is found that SMNAPs can be fabricated in high yield using12-acryloxy-9-octadecenoic acid (AOA) as the surfactant and styrene as the second monomer with the addition of2-butanone (a swelling agent). The as-synthesized SMNAPs may serve as magnetically-controllable solid surfactants to stabilize O/W immiscible mixtures, which preferentially orientated at the interface.2. Novel worm-like P(St-AA)@Fe3O4/SiO2Janus nanocomposite particles were successfully prepared. Fe3O4nanoparticles were formed at the surface of P(St-AA) microspheres by in situ chemical deposition, leading to the formation of raspberry-like superparamagnetic P(St-AA)@Fe3O4nanocomposite particles. Based on the CATB micelle template, worm-like silica body was formed at one side of the P(St-AA)@Fe3O4composite particle by a sol-gel process. The effects of different variables such as the amount of cetyltrimethyl ammonium bromide (CTAB), tetraethyl orthosilicate (TEOS) and ammonia, the composition of inorganic precursors and surfactants on the morphologies of final particles were studied. It is worth mentioning that although owing relative hydrophilic properties, the as-prepared worm-like particles can serve as solid surfactants to stabilize oil/water mixtures due to the amphiphilic difference between the two parts as well as their special morphologies, which is different from uniform spherical particles. That might provide a new category of functional solid surfactants in Pickering emulsions and the fabrication of hierarchical materials.3. Snowman-like P(St-DVB-AA)@SiO2/P(St-DVB) asymmetric composite particles could be obtained via y-ray initiated seeded emulsion polymerization after a hydrolytic condensation process on the surface of second monomer swollen P(St-DVB-AA) seeds. Effects of the amounts and kinds of second monomer and inorganic precursor, different radiation polymerization conditions including dose rates and absorbed doses on the morphology of the obtained particles were investigated. The obtained anisotropic particles can serve as ideal solid surfactants to stabilize the water-in-oil (W/O) emulsions, and soap-free hierarchical materials were obtained by polymerization of monomers in water or oil phase.4. By combining radiation seeded emulsion polymerization with hydrolytic condensation, P(St-DVB-AA)/poly[3-(methacryloxy)propyl trimethoxysilane-styrene][P(MPS-St)] hybrid particles could be facilely obtained. The morphologies of the particles could be tuned from raspberry-like to snowman-like by simply changing the feeding amount of second monomer or inorganic precursor. The fabricated raspberry-like ones could be modified to obtain hydrophobic surface with a contact angle up to146°. And the snowman-like ones could be used as solid surfactant to stabilize water/styrene (W/St) mixtures, thus hierarchical porous materials could be obtained after the polymerization of monomer phase. The preliminary application of such soap-free porous block materials in oil-polluted water treatment was also investigated.5. Superparamagnetic mesoporous hollow Fe3O4@m-SiO2particles were obtained by a simple method. Raspberry-like P(St-AA)@Fe3O4particles were used as seed particles, and P(St-AA) core could be dissolved simultaneously during the formation of mesoporous silica shell by sol-gel process, avoiding the damage to hollow shell or the troublesome post-treatments. The effects of variables as the feeding amount of CTAB, TEOS and ammonia, the composition of solvent and the sol-gel reaction time on the structure of the final particles were investigated. The preliminary application of hollow Fe3O4@m-SiO2particles as drug carrier was also studied.6. We demonstrated a facile emulsion-based interfacial reaction method for large-scale synthesis of hollow zeolitic imidazolate framework (ZIF-8) microspheres with controllable shell thickness. Noble metal nanoparticles (NMNPs, as Pd) could be encapsulated during the emulsification process thus worked as active centers for catalysis. The inherent crystalline nature of the MOF shell as well as the tunable integral structures make the Pd@ZIF-8spheres promising catalysts in selective hydrogenation of a, β-unsaturated aldehydes.更多还原