【作者】 刘蕾；

【导师】 俞书宏；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2011， 博士

【摘要】 本论文首先回顾了生物矿化过程的基本原理和碳酸盐矿物的仿生矿化研究进展,着重论述了各种影响因素对碳酸盐矿物成核和生长过程的调控作用。基于前人的研究成果,本论文结合界面效应、混合溶剂效应与聚合电解质的协同控制作用,进一步发展和丰富了碳酸钙和羟基氧化铁矿物的控制合成。通过改变矿化反应条件,合成了一系列具备新颖形貌、稳定晶型和复杂构造的无机、无机-有机复合材料,并对其晶型选择、生长机理、形成过程和功能性质等进行了深入研究和探讨。所取得的具体研究成果归纳如下:1.分别以聚合电解质聚丙烯酸（PAA）和醋酸纤维素（CA）静电纺丝纤维骨架作为晶体生长控制剂和沉积模板,通过调节溶液中PAA的浓度和矿化时间,在单根CA纤维表面上成功制备了由不同结构单元组成的碳酸钙均匀薄膜涂层。碳酸钙在CA纤维骨架上的沉积并未改变其结构形式,却在一定程度上使骨架的硬度得到提高。经过丙酮处理后,首次获得了由微管单元构成的网络状碳酸钙宏观块材。尤其值得注意的是:PAA的限制生长与CA纤维的模板效应的协同控制在碳酸钙薄膜涂层的形成过程中起着至关重要的作用。另外,延长矿化时间使首先形成的碳酸钙薄膜涂层作为二次衬底诱导更小的线状方解石介观晶体的生长。这一研究还进一步证实,无机矿物在有机基质上成核生长时,两者之间较高程度的晶格错配是可以被接受的。2.将天然植物薄膜引入矿化体系,研究其与混合溶剂和聚合电解质的协同作用对碳酸钙晶体结晶行为的影响。分别以生葱鳞茎内膜和PAA作为离子交换膜和晶体生长修饰剂,在水-乙醇混合溶剂体系中通过双扩散方法进行碳酸钙矿化反应。通过调整植物薄膜的不同表面、PAA浓度、水-乙醇体积比和溶液的初始pH值,成功合成了多种碳酸钙晶体的新颖结构——超长带状、宏观花状、薄膜状、刺球状及梭形等。生葱鳞茎内膜同时作为离子交换膜和沉积界面,可以为具有不同形貌的碳酸钙晶体提供大量成核位点。此外,这种引入生物体系的新奇合成方法也可以扩展到其它无机、无机-有机复合材料控制合成过程。3.研究了混合溶剂和聚合电解质的协同作用对碳酸钙结晶过程中热力学-动力学竞争平衡的影响。在PSS存在情况下,通过提高水-乙醇混合溶剂中乙醇的含量实现了碳酸钙晶化过程由热力学控制向动力学控制的转变,并最终表现为目标晶体形貌和晶型的显著变化。成功制备出了一系列处于不同生长发育阶段的方解石（C）介观晶体和霰石（V）复杂集合体,并捕获到了碳酸钙晶体晶型的转变过程:从纯方解石到方解石占主导的C/V混合物,最后到霰石为主的C/V混合物。因此,利用简单醇类平衡无机晶体结晶过程中热力学-动力学控制,可以对其形貌、晶型及结构组织方式等进行有效的调控。4.将仿生矿化方法应用于合成碳酸盐以外的功能性无机材料。以聚合电解质PAA为晶体生长修饰剂,温和条件下在气液界面上成功制备了大面积的FeOOH阵列薄膜。随着PAA浓度的增加,FeOOH阵列薄膜组成单元的形貌大致经历一个“薄片-稻穗-分支纤维-完美纤维”变化过程。具有不同微结构的薄膜表现出各不相同的疏水性。片状单元构成的薄膜的接触角可以高达163°,使其具备超疏水性。另外,不同的形貌还可以显著影响它对水溶液中Cd²⁺离子的去除能力。实验结果表明,纤维结构对Cd²⁺离子去除能力最高,可以达到95 %以上（pH = 9.64）。因此,选择合适的前驱物离子,可以通过仿生矿化方法,在温和条件下制备出大量具有新颖结构的无机功能材料。更多还原

【Abstract】 In this dissertation, the basic mechanisms in biomineralization process and the state of the art of carbonates biomimetic mineralization have been firstly reviewed, focusing on mediation over the nucleation and growth of carbonates exerted by several parameters. Based on previous achievements, combining the synergetic control of interface, solvent mixture and polyelectrolyte, we have further developed and enriched the controlled synthesis of CaCO₃ and FeOOH minerals. A series of inorganic and inorganic-organic composite materials with novel morphologies, stable polymorphs and complicated architectures have been successfully synthesized by altering reaction conditions. Then, we have further deeply studied and discussed the polymorphs selection, growth mechanisms and properties of these as-prepared materials. The detailed research fruits are summarized as follows:1. Using polyelectrolyte polyacrylic acid （PAA） and electrospun cellulose acetate （CA） fiber scaffold as crystal growth modifier and template respectively, uniform CaCO₃ film coatings composed of different building blocks have been successfully synthesized on each CA fibers by altering the concentration of PAA and mineralization time. This coating process improved the hardness of the scaffold to some extent while maintaining their previous frameworks. After the CaCO₃@CA composite treated with acetone, macroscopic CaCO₃ bulk materials with complex network structures consisting of a great deal of microtubes has been successfully prepared. Especially, it is worth to note that the synergetic control between the inhibiting effects of PAA and the templating effects of CA fibers played crucial role in inducing the formation of uniform CaCO₃ film coatings. Besides, with extended incubation time, the first deposited CaCO₃ film coatings would act as secondary substrates leading to the growth of thinner fibrous calcite mesocrystals. This work also provided a novel prove that a relatively high mismatch between organic and inorganic counterparts is tolerated when inorganic crystals growth occurs at organic interface.2. By introducing natural plant membrane into mineralization system, we further studied its synergy with solvent mixture and polyelectrolyte on the crystallization behavior of CaCO₃. The mineralization process of CaCO₃ was carried out by a double diffusion technology in water-ethanol solvent mixture with Allium fistulosum L. bulb inner membrane and PAA acting as ion-exchange membrane and crystal growth modifier respectively. By adjusting different surface of bulb membrane, concentration of PAA, volume ratio of water-ethanol and initial pH value, several CaCO₃ crystals with novel structures can be obtained, such as ultralong ribbon, macroscopic blossom, thin film, spiny sphere and shuttle. The bulb inner membrane, acting as both ion-exchange membrane and depositing interface, can provide CaCO₃ crystals with a large amount of nucleation sites. What is more, this novel synthesis route involving biological systems can be extended to the controlled growth of other inorganic and inorganic-organic composite materials.3. The synergy of solvent mixture and polyelectrolyte over the balance between thermodynamic control and kinetic control in CaCO₃ crystallization process has been investigated. In the presence of PSS, the switch from thermodynamic control to kinetic control in CaCO₃ crystallization process has been realized by increasing the content of ethanol in water-ethanol mixed solvent, which can be displayed by significant variations of the final morphologies and polymorphs of target mineral. Calcite mesocrystals and vaterite complex aggregates with different growth forms and developmental phases can be obtained. The phase transition of CaCO₃ from pure calcite to calcite dominated mixture and finally to vaterite dominated mixture has also been nicely captured. Thus, the addition of simple alcohols can balance the competition of thermodynamic control versus kinetic control in inorganics crystallization process, resulting in effective control over their morphologies, polymorphs and organized structures.4. Biomimetic mineralization routes have been applied to other inorganic materials except for CaCO₃. Using PAA as crystal growth modifier, large scale synthesis of FeOOH nanostructure array films have been achieved at air-water interface at ambient conditions. With the increase of PAA content, the building blocks making up FeOOH array films mainly underwent a morphological transformation of“flake—rice spike—branched fiber—fine fibers”. Distinct microstructures can endow FeOOH film with different hydrophobicities. The film composed of nanoflakes exhibited superhydrophobicity with a contact angle of 163°. The uptake capacity of FeOOH for Cd²⁺ from water can also be influenced by microshapes. The fibrous sample displayed largest Cd²⁺ removal capacity, up to 95 % when the pH value is 9.64. Thus, by selecting suitable precursor ions, a variety of functional inorganic materials with novel structures and outstanding properties can be prepared through biomimetic mineralization routes.更多还原