【作者】 王公正；

【导师】 房喻；

【作者基本信息】 陕西师范大学 ， 声学， 2007， 博士

【摘要】 近年来，磁性复合微球和具有表面图案结构的有机-无机复合微球成为人们关注的热点，而将具有磁性和表面图案结构二者结合于一体的表面图案化磁性复合微球的制备还鲜有报道。基于此，本实验室提出了以高分子微凝胶为模板通过外源和内源沉积的方法引进磁性、荧光等活性物质制备复合材料的新思想，在此思想指导下，通过改变沉积物的种类，模板组分含量等手段，设计、制备得到了一系列表面图案奇特、磁响应性好、易于修饰的磁性复合微球材料。本论文在对磁性复合微球材料和表面图案化复合材料综述基础上，结合本实验室已有研究工作，利用高分子共聚微凝胶为模板，通过变化沉积物种类，浓度，微凝胶的组成，沉积方法等手段设计、制备了多种表面图案结构各异、磁响应性不同的复合微球材料。具体来讲，主要完成了以下工作：（1）采用反相悬浮聚合法合成了丙烯酸（AA）含量不同的N-异丙基丙烯酰胺-丙烯酸共聚微凝胶P（NIPAM-co-AA）、并以其作为微反应器，通过加入Fe₃O₄胶体溶液溶胀、渗透，SiO₂前驱物四乙氧基硅烷水解（Stober法）制备了一系列微米级、具有图案结构的超顺磁性有机-无机复合微球SiO₂-Fe₃O₄-P（NIPAM-co-AA）。结果表明：微球的表面图案可以通过改变模板中丙烯酸含量来调节；磁响应性可以通过变化Fe₃O₄胶体加入量来调控；无机物沉积量的多少，决定磁性复合微球的比重大小，SiO₂沉积量越多，微球的比重相对越大，煅烧后有助于提高微球骨架和表面形貌的热稳定性。扫描电镜、透射电镜观察表明：所制备的超顺磁性复合微球SiO₂-Fe₃O₄-P（NIPAM-co-AA）球形结构完美，表面图案奇特；Fe₃O₄颗粒分布均匀、无聚集现象且被SiO₂完全包覆，无泄露。粒径统计显示：微球粒径分布较窄，单分散性好。综上所述：微凝胶的固有优点及复合微球良好的磁响应性、SiO₂的生物相容性、易修饰性等达到完美结合，显示出这类复合微球材料有可能在吸波减震、活性物质担载和缓释、快速温和吸附分离等方面获得应用。（2）考虑到上述系列磁性复合微球的形貌和性能对模板和溶胀沉积过程的依赖性，以及模板组成的变化会引起微球表面图案结构的极大变化差异，因此，在第三章工作中用N-异丙基丙烯酰胺-丙烯酸共聚微凝胶为模板，将溶胀法变为易于操作的原位沉积Fe₃O₄方法，制备了系列表面结构细密的微球，不同于前者，磁性复合微球材料的磁滞回线偏离平衡位置，存在单方向交换的磁各向异性。造成这一结果的原因是：磁性微球材料中有铁磁性和反铁磁性物质相互作用。在第五章工作中，用丙烯酰胺和甲基丙烯酸共聚微凝胶作为模板，得到了另外一种复合微球材料。类似地，通过多种手段对复合微球的结构进行了表征。不同于上述复合微球材料的表面图案结构，这类微球的表面结构略显粗糙。煅烧时，微球表面因融合而变得光滑。总的来说，磁性复合微球表面结构、磁响应性、比重等也可以通过改变反应条件来控制。这为表面图案化磁性复合微球的合成提供了更多的新思路。（3）在本论文的第三部分工作中，考虑到无机物对表面图案化微球应用的限制及对模板的特殊要求，采用N-异丙基丙烯酰胺-丙烯酸共聚微凝胶为模板，通过溶胀法制备了互贯网络表面图案化有机-有机复合微球脲醛树脂-P（NIPAM-co-AA）材料，研究了酸度、尿素和甲醛浓度、配比等对所形成复合微球表面图案结构的影响，通过扫描电镜、冷冻干燥等对其进行表征。结果表明：以甲醛与尿素配比为1：2和3：1在P（NIPAM-co-AA）模板微球表面形成的丝状网络结构复合微球和小球密堆积结构表面形貌最为典型，从而使模板法制备复合微球的模板变得多样化，为模板法制备更多结构特异的复合微球材料奠定了基础。（4）最后将环氧树脂与磁性有机-无机复合微球材料混合制备成测试块，研究了它们的吸声性能，结果表明该磁性复合材料在高频范围吸声效果较好，有望在吸波减震、降噪等领域获得应用。本论文的主要创新点：（1）首次以溶胀的方法将纳米级超顺磁性微粒均匀引入到微米级复合微球中，从而使得所制备的微米级微球具有超顺磁性。同时表面图案的存在大大增加了此类微球的比表面积。（2）根据实验所建立起来的方法，可以大幅度调整微球的表面结构、表面性质、微球的磁响应性以及微球中有机无机成分的相对比例。（3）建立了微纳米颗粒超声吸收模型。更多还原

【Abstract】 In recent years, magnetic composite microspheres and organicinorganic composite materials with patterned surface structures have attracted growing attention due to their potential applications. Preparation of composite microspheres with patterned surface structures integrated with super-paramagnetism has seldom reported in literatures. Based upon this consideration, a new strategy for preparing composite materials via introducing magnetism into template in a manner of outer and inner sediment on/in microspheres was proposed in our laboratory, and a series of the magnetic composite micrspheres exhibiting novel surface morphologies, which have excellent magnetic responsibility, and easiness in the chemical modification of their surfaces, were successfully created by simply varying kinds of aggradations and the ratio of the two monomer units in the template microgels, etc. respectively.On the bases of the above-mentioned research works conducted in our laboratory and the review （Chapter 1） on magnetic composite microspheres and composite materials with patterned surface structures, several magnetic composite microspheres were designed and prepared. It has been demonstrated that the magnetic responsibilities and surface structures of the microspheres we produce can be adjusted via various ways. The main works conducted in my thesis are outlined below.First, N-isopropylacrylamide （NIPAM） and acrylic acid （AA） copolymer microgels P（NIPAM-co-AA） of different amount of AA were prepared by employing a reverse suspension polymerization technique. The polymeric microgels were used firstly as micro-containers to include Fe₃O₄ nano-particles and then as micro-reactors to control the hydrolysis of tetraethyl orthosilicate （TEOS）. In this way, various superparamagnetic composite microspheres SiO₂-Fe₃O₄-P（NIPAM-co-AA） with different morphologies in the micrometer size range were prepared. It was demonstrated that the sensitivity of the composite microspheres to external magnetic field was controlled by the amount of Fe₃O₄ adding; the morphologies of the composite microspheres could be tailored to a certain extent by either varying the ratio of the two-monomer units in the template microgels or the amount of SiO₂ deposited. The more the amount of SiO₂ deposited, the more specific gravity of microspheres was, and then after calcined, thermal stabilities of the skeleton and morphologies of microspheres enhanced. Images of SEM and TEM show that the microspheres morphology is novel and perfect, Fe₃O₄ nano-particles were dispersed uniformly in the microgel templates and coated completely by SiO₂. Statistic results of microspheres size indicated that the particles sizes are about 35μm and occupied a good monodispersity. The excellent magnetic responsibility of the composite microspheres, the easiness of modifying of the surfaces and the better biocompatibility of SiO₂ may make the microspheres find important uses in the mild separation of bioactive materials, loading of active materials, and radiation and shock absorption, etc.Considering the fact that the morphologies and performance of magnetic composite microspheres depend on the depositing methods and the microgels templates, the swelling method was substituted with preparation of Fe₃O₄ in-situ during the preparation process of the magnetic composite microspheres. A series of magnetic composite microspheres with fine patterned surface structures were prepared and characterized. Compared with the microspheres mentioned above, the magnetic hysteresis loops of the composite microspheres are not identical, asymmetrical loop, which clearly revealed the presence of unidirectional exchange anisotropy, which can be understand by the interaction between an anti-ferromagnetic material and ferromagnetic material. Besides this work, we also introduced acrylamide （AM） and methyl acrylic acid （MAA） copolymer microgels as template, and got another kinds of composite microspheres with fancy morphology. The surface became smoother after calcinations. In general, simply adjusting the reaction condition could control the surface structures, the magnetic responsibility and the density of these magnetic microspheres. This offers a new strategy for designing and preparation of the super-paramagnetic composite microspheres with patterned surface structures.In the third part of this thesis, a lot of full-IPN urea-formaldehyde resinP（NIPAM-co-AA） （UFR-P（NIPAM-co-AA）） polymer composite microspheres with patterned surface structures were prepared by employing P（NIPAM-co-AA） microgel as a template. This organic-organic composite microspheres were designed and to be prepaed in order to extend the applications of the microspheres with patterned surface structures. The influence of acidity, concentration, the ratio of urea and formaldehyde on the surface pattern structures of the UFR-P（NIPAM-co-AA） composite microspheres were interrogated by using SEM and FTIR techniques. It was demonstrated that the morphologies of the polymer-polymer composite microspheres are determined by the initial ratios of urea to formaldehyde. As examples, the morphologies of the surfaces are characterized by a network and a dense deposit structures when the ratio are 1:2 and 3:1, respectively. Furthermore, these fancy pattern structures, which may offer a diversification template for preparing composite microspheres, make them worth to be exploited further.Acoustic absorbing test of the magnetic composite microspheres with patterned surface structures have been measured with an ultrasonic system, the magnetic composite materials. The magnetic microspheres were compounded into epoxy resin during the absorbing test. It shows good performance at high frequency ranges. It is anticipated that the magnetic composite microspheres may be used as novel materials for radiation absorbance and shock absorption.The main contributions of this thesis are as follow:（1） A swelling method was used firstly to introduce super-paramagnetic Fe₃O₄ nano-particles into polymeric microgel templates and via this way, a number of inorganic-organic composite microspheres of a size in the micrometer range with patterned surface structures and super-paramagnetic properties have been succefully prepared.（2） The patterns of the surface structures, the chemical properties of surface, and the magnetic responsibility of the composite microspheres could be adjusted in a great range, according to the methodology we established in this work.（3） The model for acoustic absorbing measurement of the panicles in micrometer or nanometer size range was proposed.更多还原