【作者】 赵丽娜；

【导师】 王子忱；

【作者基本信息】 吉林大学 ， 物理化学， 2009， 博士

【摘要】 碳酸钙作为最主要的生物材料之一,其结构和形貌决定着它的各项性能,因此本文采用化学控制与表面修饰结合的方法,选用一系列有机质,制备出具有多种特殊形貌的碳酸钙材料,并对其形成机理进行了探讨。在反应过程中,有机质不仅改变碳酸钙的表面性质,而且对碳酸钙成核和生长起到控制作用。这一技术具有开创性,而且具有广阔的工业应用前景。第一章是绪论,介绍了碳酸钙工业的发展概况、纳米碳酸钙的性质、制备与表面修饰以及本文选题的目的和意义。第二章采用沉淀反应方法,利用聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDS)复合添加剂作为有机模板,制备了中空球状方解石型碳酸钙,同时考察了不同温度、SDS和PVP浓度对碳酸钙结晶和聚集行为的影响,进而对其反应机理进行了初步探讨。第三章采用沉淀反应法,以工业上常见而廉价的聚丙烯酸(PAAS)作为有机质,制备了蝶状文石型碳酸钙,考察了一系列条件对于文石型晶体成核及生长的影响,并初步探讨了其生长机理。第四章采用碳化法以聚丙烯酸(PAAS)作为添加剂,制备出具有完整率高且分布均匀的针状方解石型碳酸钙粒子,找到了适合针状方解石碳酸钙粒子生长和稳定存在的条件,初步探讨了针状方解石型碳酸钙粒子的生长机理。第五章选取聚乙二醇(PEG)为有机质,采用碳化法制备出棒状方解石型碳酸钙,并推测了其反应机理。第六章利用碳化法,选用了几种常见的表面改性剂(硬脂酸钠、十八碳醇磷酸酯和油酸)对其进行了表面改性。通过有机质控制碳酸钙的晶体形状与大小,同时改变碳酸钙的表面性质,所得碳酸钙粒子由亲水疏油性直接转化为疏水亲油,并提出了合理的碳酸钙表面改性原理。此方法为改性碳酸钙生产提供了一定的理论基础,也为新型材料的研究提供了更加广阔的空间。综上所述,本文对于充分利用我国丰富的石灰石矿产资源,研究、开发和制备碳酸钙产品的新方法、新工艺,从而进一步提高其产品的质量和附加值具有重要意义。同时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,对碳酸钙表面改性的工艺过程和质量控制将起到一定的指导作用,甚至对其他粉体材料的表面改性也具有一定的参考价值。更多还原

【Abstract】 Calcium carbonate is the extensive chemical industrial products as a novel functional material used in the fields such as plastics,rubber,paint,printing ink, weaving,toothpaste,makeup,commodity,foodstuff,and so on.Nanoparticles as an important harvest of nanotechnology have attached many attentions in the field of materials science.In recent years,the controlled synthesis of inorganic particle materials with specific size and morphology has attracted more and more attracted due to their wide potential applications in many fields.However,calcium carbonate nanoparticles 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.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 join the techniques of chemical synthesis and surface modification are performed.As a result,a series of functional calcium carbonate nanoparticles are prepared under kinds of effective controls.The results indicate it is an available and ideal strategy.If the calcium carbonate produces exert farthest action in the goods,the technologies are eligible necessarily such as purity,granularity,whiteness of calcium carbonate products.At present,the mainstream aspect of this industry is the synthesis of products with high purity,good dispersion and small granularity.It is realized by improving technologies,equipments and optimizing the reaction conditions.In the paper,the novel calcium carbonate materials are synthesized using a series of organic substrates via the chemical controlling and surface modification.The organic substrates can not only change the surface properties of calcium carbonate but also control the nucleation and growth of products.The technology has certain innovation and the extensive application foreground.Firstly,the CaCO₃ hollow spheres were successfully synthesized by facile precipitation reaction of aqueous solutions CaCl₂ and Na₂CO₃ in the presence of polyvinylpyrrolidone（PVP） and sodium dodecyl sulfonate（SDS）.Introducing the surfactant/polymer composite into reaction system is in order to not only understand the effects of the surfactant/polymer composite on the crystallization and aggregation of calcium carbonate,but also explore a possible realized and simple preparation method. The products were characterized by FESEM,TEM and XRD.At the same time,the experimental conditions were investigated to explore the crystallization and aggregation of calcium carbonate.The reaction mechanism was discussed in this work.Secondly,the butterfly-like aragonite calcium carbonate particles were successfully prepared through a facile precipitation reaction of Na₂CO₃ with CaCl₂ in the presence of polyacrylic acid sodium（PAAS）.The as-prepared products were characterized with scanning electron microscope and X-ray diffraction.The effects of the reaction temperature and the concentration of PAAS on the nucleation and growth of aragonite crystals were investigated.The possible growth mechanism of the dendrite-shaped aragonite particles was discussed.This research not only can make us further understood the general principles of the reaction,but also can open up a new avenue of industrial production of CaCO₃ particles with exquisite and unique morphologies due to the preparation method employed by us is simple,low-cost,mild condition.Thirdly,needle-shaped calcite CaCO₃ nanoparticles were prepared in aqueous solution via carbonation method in the presence of polyacrylic acid sodium（PAAS）. In this paper,the organic substrate could not only control the morphology of calcium carbonate but also induce the nucleation and growth of CaCO₃.The needle-like CaCO₃ with a length about 1μm,a diameter about 70 nm and the ratio of length to diameter about 15:1 was prepared.The products were characterized by XRD,FESEM, TEM,FT-IR,DT-TGA,Whiteness and the contact angle.The results reveal that the surfactant plays important roles in determining the structure and morphology of the sample.Fourthly,the rod-like CaCO₃ with a diameter about 100 nm and the ratio of diameter to length about 1:4 was successfully synthesized via bubbling CO₂ gas in the presence of polyethlence glycol（PEG）.The bubbling effect of PEG increased the retention time and contact area of CO₂ in the solution thus the higher carbonation efficiency was observed.The presence of PEG accelerates the period of absorption and shortens the time of carbonation.We have succeeded in surface modification of CaCO₃ with PEG.Finally,Modified calcium carbonate（CaCO₃） nanoparticles with cubic and spindle-like configuration were synthesized by the typical bobbling（gas-liquid-solid） method.Such modifiers as sodium stearate（NaSt）,octadecyl dihydrogen phosphate （ODP） and oleic acid（OA） were used to obtain hydrophobic nanoparticles.The different modification effects of the modifiers were investigated by measuring the active ratio,whiteness and the contact angle.Moreover,transmission electron microscope（TEM）,X-ray diffraction（XRD） and thermogravimetry analysis（TGA） were employed to characterize the obtained products.A preliminary reaction mechanism is discussed in this paper.According to the results,the active ratio of CaCO₃ modified by ODP was ca.99.9%and the value of whiteness was 97.3%when the dosage of modifiers reached to 2 wt.%.Moreover,the contact angle was 122.25°for the CaCO₃ modified in the presence of NaSt,ODP and OA.A conclusion could be drawn from the above results that the compatibility and affinity between the modified CaCO₃ nanoparticles and the organic matrixes were greatly improved.In this thesis,we attempted a biomimetic method to obtained calcium carbonate nanoparticles with special properties,introduced a novel ideal to synthesis calcium carbonate nanoparticles.Surface modification technique employed during preparation process,which introduced functional groups upon the surface of calcium carbonate nanoparticles 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 production of calcium carbonate in the future.更多还原