【作者】 文男赓；

【导师】 武利民； 游波；

【作者基本信息】 复旦大学 ， 材料物理与化学， 2009， 硕士

【摘要】 近年来,聚合物/二氧化硅纳米复合乳液越来越受到人们的关注,这不仅是由于聚合物/二氧化硅复合乳液兼有有机材料和无机材料的优点,即具有有机相的易加工性、柔韧性以及无机材料的刚性、热稳定性等特点;还因为聚合物和二氧化硅可以协同作用,产生一些新的性能。本文通过无皂方法制备了草莓型的聚醋酸乙烯酯（PVAc）/二氧化硅纳米复合乳液,表征了乳胶膜的物理性能。还采用原位法和共混法制备了聚苯乙烯-丙烯酸酯/二氧化硅复合乳液,并在聚合物/二氧化硅纳米复合乳液高温成膜过程中,得到了有序多孔结构;低温成膜过程中,得到了有序胶体晶体结构。本文探讨了成膜温度,二氧化硅含量,乳胶球粒径,成膜时间,共聚单体比例等因素对有序结构的影响。利用SEM,TEM,XPS,粒径分析等手段对有序结构进行了详细表征。具体研究内容及结果如下:（1）在纳米二氧化硅粒子存在下,以醋酸乙烯酯（PVAc）为单体在水相中自由基乳液聚合,通过氢键与纳米二氧化硅粒子表面的羟基相互作用,将有机-无机相结合起来,制备了在水相体系中稳定的具有草莓型结构的PVAc/SiO₂纳米复合乳液。即聚合物颗粒表面吸附了大量纳米二氧化硅粒子,作为稳定剂对乳液起稳定作用。为提高乳液的固体含量,可以加入少量可聚合活性单体与纳米二氧化硅粒子共同作用,得到固含量40%左右的乳液。透射电镜和扫描电镜显示所得复合微球具有草莓型结构,且二氧化硅于表面富集,复合微球粒径介于200～500nm之间。该复合乳液成膜后,相比于商品醋酸乙烯酯乳液（如白乳胶）,耐水性明显增强,同时膜的硬度也有较大提高。（2）采用原位乳液聚合方法制备了苯乙烯-丙烯酸丁酯-丙烯酸三元共聚物/二氧化硅纳米复合乳液。当上述纳米复合乳液在大于100℃的温度下烘干成膜时,得到的涂膜具有有序多孔结构。这种孔结构的形成是由于在高温下,水份快速挥发,包覆在聚合物粒子周围的纳米二氧化硅粒子通过硅羟基缩合形成了固定的二氧化硅骨架,而聚合物分子及链段在高温下易于流动,会扩散到二氧化硅骨架的空隙中,导致聚合物粒子塌陷,从而产生多孔结构。采用TEM、SEM、XPS、反射光谱仪等分析手段研究表明,孔洞的直径、深浅可由纳米SiO₂粒子的用量、聚合物乳胶粒子尺寸、涂膜厚度、干燥温度等调节。多孔材料还具有结构性颜色效应。（3）先用乳液聚合法合成了苯乙烯-丙烯酸丁酯-丙烯酸三元共聚物乳液,然后再与胶体纳米二氧化硅粒子共混制备了纳米复合乳液。通过室温下干燥,直接得到了具有较高力学强度的三维有序胶体晶体材料。采用TEM、SEM、反射光谱仪等分析手段研究了聚合物乳液的粒径、共聚物组成、纳米二氧化硅含量等对胶体晶体结构及形貌、胶体晶体结构性颜色反射峰的影响。通过调节聚合物乳胶粒子的大小,可以得到不同颜色的胶体晶体。更多还原

【Abstract】 In recent years,the strategy to fabricate polymer/silica nanocomposites is of burgeoning interest,not only because such materials have the strength of organic and inorganic materials,but also because such materials can display novel and enhanced properties（e.g.mechanical,chemical,electrical,thermal and optical）.In this study,polymer/silica nanocomposite spheres with raspberry-like were obtained via surfactant-free methods,and properties of the films were investigated. Also Poly（St-BA-AA）/SiO₂ nanocomposite emulsions were prepared via in suit or blending method.Some ordered porous structures were observed after the latex was coated on the substrate and dried at a high temperature;or some ordered colloid crystals were obtained at room temperature.Temperature,monomer composites, nanosilica content,particle size and etc were studied on the influence of the morphology of the ordered structure.And the properties of the films were investigated by TEM,SEM,XPS and Reflection spectra,etc.All the research contents and results are as follows:（1） We used Poly（vinyl acetate）（PVAc） as the monomer and successfully synthesized a series of long-stand stable raspberrylike PVAc/SiO₂ nanocomposite particles via a "surfactant-free" heterophase polymerization in the presence of an ultrafine aqueous silica sol and water as the continuous phase.Since the surface of silica particle is surrounded by hydroxyl group,the hydrogen-bond between PVAc and silica should promote the compatibility between polymeric phase and nanosilica phase.Some influencing parameters such as initial silica varieties,silica content were investigated in detail,and a possible formation mechanism of raspberrylike nanocomposite particles was also discussed.And properties of the films such as water resistance and hardness were investigated.（2）This part presents a novel and facile method for the fabrication of nanocomposite films with ordered porous structures.In this approach,a water-borne poly（styrene-co-butyl acrylate-co-acrylic acid） / silica nanocomposite emulsion was synthesized in situ emulsion polymerization.When this latex was dried to form a film at a high temperature（above 100℃）,an ordered porous structure could be directly obtained in the nanocomposite film.This was probably during a fast evaporation rate of water,silica particles transform into hard silica framework via the condensation of silianol groups.Meanwhile,soft polymer particles can easily collapseand immigrate into the voids existing in silica framework to form ordered porous structure in the nanocomposite film.SEM,TEM were employed to observe the morphology,XPS and particle analyzer were used to analyze the surface composition of the ordered porous nanocomposite film and the particle size,respectively.（3） An one-step strategy to fabricate large-scale ordered colloid crystals has been proposed,in which a nanocomposite emulsion composed of polymer latex and colloidal silica is blended first,and then drying on a substrate under room temperatures to directly obtain a robust film with three-dimensionally array of colloid spheres.This strategy is really simple and inexpensive:Neither complex processes nor special equipments are needed,as large as several square meters colloid crystal can be fabricated on any substrates without any templates.This technique presents a new paradigm in the preparations of colloid crystals.The particle size of polymer particles,morphology and optical properties of colloid crystal films were investigated by TEM,SEM,Reflection spectra and particle analyzer.The films have very beautiful iridescence phenomena and regular periodicity.更多还原