【作者】 王成毓；

【导师】 王子忱；

【作者基本信息】 吉林大学 ， 物理化学， 2007， 博士

【摘要】 本论文模拟生物矿化过程,以有机质控制碳酸钙的成核和生长,原位制备具有独特显微结构特点的功能性纳米碳酸钙,并使碳酸钙具有优异的物理和化学性能。第一章为前言,介绍了纳米碳酸钙的性质、合成与表面修饰以及仿生矿化的原理、应用和功能性纳米碳酸钙的合成方面的研究现状与发展。在第二章中,采用自制磷酸酯为有机质,仿生矿化原位合成疏水性纳米碳酸钙。在碳化法中,磷酸酯与氢氧化钙反应生成的磷酸酯钙在反应中控制晶体的成核生长,改变碳酸钙的表面性质。复分解法中,有机质抑制了文石的生长。有机质与碳酸钙发生化学反应生成磷酸酯钙,改变碳酸钙的表面性质。在第三章中,采用油酸为有机质,仿生矿化原位合成疏水性纳米碳酸钙。在碳化法中,油酸对产物起颗粒尺寸控制剂和表面改性剂的双重作用。复分解法得到花状活性碳酸钙。由于制备的碳酸钙表面C=C双键的存在,不仅产品本身可以在一定条件下发生聚合,而且可以与有机单体发生共聚。在尿素水解法中,制备出文石和球霰石两种碳酸钙中教不稳定的晶态结构。在第四章中,采用硬脂酸钠为有机质,仿生矿化原位合成疏水性纳米碳酸钙。在碳化法中,在自制的硬脂酸钠参与下得到纺锤形活性碳酸钙。复分解法得到片状文石型活性碳酸钙。在第五章中,选取十二烷基甜菜碱作为有机质,仿生矿化原位合成自分散性纳米碳酸钙,产品在不搅拌、不振动的条件下自动扩散到水中,并能稳定、均匀地分散在水中很长时间。甜菜碱具有发泡性,可以缩短反应时间。在第六章中,聚丙烯酰胺有机质对产品的晶型、晶粒度和形貌都起到很好的控制作用。本论文获得了一些创新性的研究成果,在碳酸钙的合成和表面修饰中引入新的思路,具有广阔的工业应用前景,同时对仿生矿化的实际应用具有指导意义。更多还原

【Abstract】 CaCO3 is one of the important fillers used in the industries of plastics, rubber, paint, and so on. Nanoparticles as an important harvest of nanotechnology have attached many attentions in the field of materials science. However, the nano-CaCO3 are easily aggregate because of the very small particle size, high surface activity and high surface energy. Therefore, controlling the particle size during the preparation process, avoiding the aggregation of particles and inducing the powders to redisperse in the medium are current‘hot topics’in the field of nanomaterials. Surface modification of CaCO3 would lead to a great expansion in its applications; since mineral particles are hardly dispersed in a polymer matrix. Biomineralization is mother natures approach to advanced materials synthesis, and it attempts to chemically control the growth of inorganic crystals in the organic substrate by adapting or imitating biological mineralization strategies. The key to the successful synthesis of an inorganic-organic composite is an understanding of the parameters that control the nucleation and growth of inorganic crystals under the organic substrate in aqueous solution. In this thesis, a research on combine the techniques of chemical synthesis and surface modification are performed. In-situ surface modification technique is took place during the preparation via mimicking the essential functions of biomineralization. As a result, a series of functional nano-CaCO3 are prepared under kinds of effective controls. The results indicate it is an available and ideal strategy.We synthesize octadecyl dihydrogen phosphate (C18H37OPO3H2) as organic substrate which can make interfacial recognition of molecules with mineral. The organic substrate shields the solid surface through C18H37OPO3Ca, which decreasing dramatically its surface energy and hence facilitate the dispersion of the filler in a polyolefinic matrix, on the other hand, enhance the compatibity between filler and matrix leading possibly to better mechanical performance of the composite. The spindle-like hydrophobic CaCO3 nanoparticles with a mean diameter less than 0.1μm and the radio of diameter to length about 1:3.5 can be synthesized in situ by a carbonation process in the presence of organic substrate. The active ratio of the product reaches 99 %. As the concentration of organic substrate increased, the active ratio of the hydrophobic CaCO3 increased and the mean particle length increased at the same time. Hydrophobic calcium carbonate nanoparticles were prepared via crystallization of calcium carbonate whereby aqueous solutions CaCl2 and Na2CO3 are combined with C18H37OPO3H2 in methanol. In the experiments, the surfactant could not only control the crystal shape but also modify the surface of calcium carbonate. The ellipse-like nano-CaCO3 particles with an average diameter of 40 nm have been obtained under given experimental conditions. The crystal polymorph of the final particles was aragonite and calcite. The contact angle analysis indicated that the final calcium carbonate was hydrophobic. We have succeeded in surface modification of calcium carbonate in situ.Hydrophobic CaCO3 particles were prepared in situ by carbonation of Ca(OH)2 slurry in the presence of the ethanol solution of oleic acid by mimicking the process of biomineralization. The oleic acid solution was used in precipitation process to control the particle size and to modify the surface of CaCO3 particles simultaneously. In this study the ellipse-like CaCO3 particles in the average diameter of about 50 nm can be synthesized. By changing the weight ratio of oleic acid to CaCO3, the surface property of CaCO3 particles was changed from hydrophilic to hydrophobic. The active ratio of the modified CaCO3 might reach 100 %. The contact angle of the modified CaCO3 was 108.77 o. IR spectrums of the CaCO3 particles showed the appearance of the alkyl groups from the oleic acid. Hydrophobic vaterite nanoparticles were prepared via crystallization of CaCO3 by mimicking the process of biomineralization, whereby aqueous solutions CaCl2 and Na2CO3 are combined with oleic acid in methanol. The organic moieties shield the solid surface through the reaction of–COO- groups of oleic acid with Ca2+, which decreasing dramatically its surface energy and hence facilitate the dispersion of the filler in a polyolefinic matrix. High concentration of oleic acid gave stable vaterite crystals covered with the hydrophobic species. The present stable monodispersed spherical vaterite particles would be expected to be excellent as stable pillaring precursors in several polymer matrixes. The C=C bonds of oleic acid can be copolymerization with organic monomer, and this is potentially important for industrial process of biomineralization. Two metastable calcium carbonate polymorphs, rod-like aragonite and spherical vaterite are selectively formed using hydrolyzation of urea. Aragonite rods were synthesized from a calcium acetate (Ca(AC)2) and urea (CO(NH2)2) solution under given condition. In contrast, the addition of oleic acid results in the formation of spherical vaterite. The results show that oleic acid can be used as additive to select the polymorph from aragonite and vaterite.Hydrophobic CaCO3 nanoparticles were prepared in aqueous solution via carbonation method by mimicking biomineralization. In this paper, C17H35COONa solution synthesized by C17H35COOH and NaOH was used as organic substrate and growth medium for CaCO3. This organic substrate could not only induce the nucleation and growth of CaCO3 but also make the surface of CaCO3 hydrophobic. The spindle-like CaCO3 with a diameter about 10 nm and the ratio of diameter to length about 1:4 was prepared. According to the floating ratio test, the active ratio of the products exceeded 99 % at an appropriate condition. A simple synthetic method for the preparation of hydrophobic lamellar aragonite has been developed, whereby aqueous solutions CaCl2 and Na2CO3 are combined with sodium stearic in methanol at 60 oC. The results reveal that the surfactant plays important roles in determining the structure and morphology of the sample. The contact angle of the modified aragonite reached 108.59 o. We have succeeded in surface modification of particles in situ.CaCO3 nanoparticles with about 50 nm in size could be prepared by carbonation reaction of a mixture of Ca(OH)2 and dodecyl dimethyl betaine (BS-12) via bubbling CO2 gas. The results indicate that the CaCO3 powder samples can self-diffuse in water, thus forming a suspension with enhanced stability and longevity. The bubbling effect of BS-12 increased the retention time and contact area of CO2 in the solution thus the higher carbonation efficiency was observed. The presence of BS-12 accelerates the period of absorption and shortens the time of carbonation. We have succeeded in surface modification of CaCO3 with BS-12.A carbonation route for the synthesis of nano-sized calcium carbonate (aragonite) was studied. In the process, poly-acrylamide (PAM) was used as an organic substrate to induce the nucleation and growth of calcium carbonate. The calcium carbonate particles were produced by means of carbonation of the mixture of calcium hydroxide and poly-acrylamide by bubbling CO2/N2 gas mixture. The synthesized calcium carbonate particles in the presence of organic substrate are the mixture of aragonite with needle shape and calcite with cubic shape. The–NH2 groups of poly-acrylamide could adsorb onto the growing crystal face and suppress the transformed of aragonite into calcite.In this thesis, we attempted a biomimetic method to obtained nano-CaCO3 with special properties, introduced a novel ideal to synthesis nano-CaCO3. In-situ surface modification technique employed during preparation process, which introduced functional groups upon the surface of nano-CaCO3 overcoming the agglomeration of nanoparticles. For the benefits of simple、uninterrupted and inexpensive, this innovatory technique has potential use in application and guide meaning in large-scale industrialization manufacture of nano-CaCO3.更多还原