乙醇/水混合溶剂体系中碳酸钙晶体晶型和取向的控制

采用(NH4)2CO3分解法,制备得到了晶型和形貌可控的CaCO3晶体。研究结果表明,乙醇/水混合溶剂、陈化时间和L-半胱氨酸自组装单层模板对CaCO3晶体的晶型、取向和形貌都具有重要影响。无单层模板情况下,溶液中主要得到了球霰石,球霰石的形貌随陈化时间从花朵外形变为树叶形。同样的醇/水体系中,在自组装单层上却得到了取向为(104)晶面的方解石。这与水溶液中同一自组装单层上主要获得(001)结晶面的方解石有明显不同。方解石的形貌也随陈化时间变化而改变。陈化时间为3h时,得到具有孔洞结构的方解石;陈化时间为12 h时,得到表面光滑的菱面体方解石。     

3-巯基丙酸自组装单层控制碳酸钙晶型及形貌的研究

采用碳酸铵分解产生的NH3和CO2扩散并溶入氯化钙溶液中,得到了碳酸钙晶体。研究结果表明,3-巯基丙酸自组装单层和溶液温度对碳酸钙晶体的晶型和形貌具有重要影响。25℃条件下,纯溶液中得到了方解石,文石和球霰石三种晶型的混合沉淀物,而在自组装单层存在条件下只得到了表面光滑的菱面体方解石。改变温度,自组装单层调控得到的方解石晶体具有不同的形貌。在60℃得到了多孔方解石,与25℃时典型菱面体方解石有重要区别。XRD分析表明自组装膜上所得碳酸钙晶体为沿着(104)和(006)晶面取向生长的方解石。     

PAMAM树形分子对CaCO3结晶影响的研究

研究了不同端基的聚酰胺胺(PAMAM)树形分子对CaCO₃在水溶液中结晶的影响。分别利用傅立叶变换红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)等测试手段对样品进行了分析。结果表明:没有树形分子存在时CaCO₃是粒径为10μm的菱形方解石晶体;端基为-COONa的树形分子存在时CaCO₃则是粒径为1～2μm的球形球霰石晶体;-COOCH₃端基PAMAM树形分子存在时得到的CaCO_{3相似文献}   

CO2鼓泡法可控制备单层中空CaCO3微球:染料负载及细胞生物成像

在L-蛋氨酸（L-Met）的导向下,可控制备了一种单层中空CaCO₃微球。考察了L-Met的加入量、CO₂流速和反应温度等重要参数对CaCO₃形貌、尺度和晶相的影响。作为一种客体分子载体,该单层中空CaCO₃微球可负载罗丹明B（RhB）,得到一种发光复合材料（RhB@hollow-CaCO₃）。RhB@hollow-CaCO₃）对A-549肺癌细胞（A549 LCCs）和HO8910人卵巢癌细胞（HO8910 OCCs）表现出良好的生物相容性。     

超支化双亲水性嵌段共聚物对CaCO3结晶影响的研究

采用合成的聚乙二醇-超支化聚酯(PEG-hb-DMPA)的线性-超支化杂化二嵌段共聚物, 探讨了羧端基树状功能化的杂化嵌段共聚物对CaCO₃结晶的影响，并用FTIR、XRD、SEM等对产物进行了表征。结果表明，羧端基的双亲水性嵌段共聚物对CaCO₃结晶形貌乃至晶型均具有显著调控作用，比较高的浓度(1.67 g·L^-1, >10 min)或较低浓度作用较长时间(0.33 g·L^-1, 24 h)均得到了呈较均匀球粒形态的球霰石CaCO₃结晶。     

CaCO3纳米微粒的层状液晶模板法制备及其生长过程中的形貌演变

在Triton X-100/n-C₁₀H₂₁OH/H₂O体系中，低角X射线衍射测试表明层状液晶的溶剂层厚度小于3 nm。利用层状液晶为模板制备了CaCO₃纳米微粒，并用透射电子显微镜(TEM)、X射线衍射(XRD)和选区电子衍射(SAED)进行了表征。TEM结果表明所得CaCO₃纳米粒子的形貌为球形，粒径在2～8 nm，分布较窄。XRD表明CaCO₃纳米微粒的物相为方解石型和球霰石型混合结构。在制备过程中，Ca(OH)₂的加入和CaCO₃纳米微粒的析出并未破坏层状液晶的对称性和长程有序性。此外，在Triton X-100/CH₃CH₂OH体系中，研究了CaCO₃纳米微粒的生长行为，发现小的纳米微粒先通过导向聚集生长成小的梭状物，然后小的梭状物继续生长，最后发生Ostwald陈化形成较为均一的两头尖的带状纳米结构，其宽度在50～200 nm，长度约为2 μm。     

聚电解质膜PDAC/PSS诱导CaCO3结晶的研究

以模拟软体动物珍珠层的周期性基质控制形成过程制备仿生层状复合材料. 将聚苯乙烯磺酸钠(PSS)与聚二烯二甲基氯化铵(PDAC)用逐层浸渍的方法使其组装成多层膜, 用于诱导过饱和溶液中CaCO₃的结晶, 详细研究了膜紫外吸收随组装层数增加的线性变化. 扫描电镜和X射线衍射表征了晶体的形貌和结构. (PDAC/PSS)₁₅PDAC膜诱导获得的CaCO₃晶体为六面体结构, 晶体尺寸为30～40 μm; (PDAC/PSS)₁₅膜诱导CaCO₃结晶, 可以在膜表面获得形貌与珍珠层非常相似的CaCO₃晶体, 结晶10 h获得的晶片结构呈规则的六边形, 片尺寸约为10～20 μm. X射线衍射结果表明两种晶体的晶格结构与天然珍珠层差异明显, 说明静电作用为晶体形貌的主控因素之一, 但不是晶格结构的决定因素. 复合材料断面电镜照片表明其为层状结构.     

双亲水性嵌段共聚物对CaCO_3结晶的影响

以合成的带有磺酸基为端基的线型-超支化二嵌段共聚物PEG-b-PEI-SO3H为模板,探讨了其对CaCO3结晶的影响,并用FTIR、XRD、SEM、TEM等对产物进行了表征.结果表明,带有—SO3H端基的线型-超支化双亲水性嵌段共聚物PEG-b-PEI-SO3H对CaCO3晶体形貌和晶型表现出较强的调控能力.培养1天时得到空心环状方解石型CaCO3晶体,但当培养时间为3天和5天时,得到的CaCO3晶体形貌既有河蚌状也有类球状,同时其晶型既有方解石也有球霰石,而当培养时间达到7天后,得到的就只有球状球霰石CaCO3晶体.     

蔗糖/精氨酸体系中碳酸钙结晶的仿生合成

该文以更加接近生物矿化的方法研究了蔗糖/精氨酸体系对碳酸钙晶体取向、形貌和晶型的控制作用.XRD 分析表明,在蔗糖/L-精氨酸混合体系中合成的晶体主要为碳酸钙的球霰石晶型及少量的方解石型,在单独的蔗糖或L-精氨酸溶液中基本是球霰石晶型.SEM分析表明,蔗糖和L-精氨酸均可诱导形成特殊形貌的碳酸钙.实验结果表明,蔗糖/精...     

六偏磷酸钠对碳酸钙矿化的影响

常温下,在CaCl2与NaCO3反应体系中加入一定量的六偏磷酸钠调控合成CaCO3晶体,用粉末XRD衍射仪、FT-IR对合成的晶体进行了表征,用扫描电子显微镜观察分析了生成的CaCO3晶体的形貌,研究了六偏磷酸钠浓度对CaCO3晶型和形状的影响。研究表明:在水体系中,CaCl2与NaCO3反应生成CaCO3晶体,当加入六偏磷酸钠的量小于50mg时,得到的是纯的方解石晶型,当加入六偏磷酸钠的量大于80mg时,得到的是方解石和球霰石的混合体,随着六偏磷酸钠量的增加,生成的球霰石晶体增多,实验结果说明六偏磷酸钠对球霰石晶体有一定的稳定作用。     

Crystallization of calcium carbonate controlled by Pluronic P123 in room-temperature ionic liquid

The crystallization of calcium carbonate (CaCO₃) controlled by Pluronic P123 in a room-temperature ionic liquid, ethylamine nitrate (EAN), was investigated. The CaCO₃ aggregates were obtained by rapid mixing of ammonium carbonate ((NH₄)₂CO₃) and calcium chloride (CaCl₂). Cubic calcite, spherical vaterite, and bagel-like vaterite were obtained easily by changing P123 concentration and reaction temperature. The morphologies of the as-prepared CaCO₃ aggregates were investigated by transmission electron microscopy and scanning electronic microscopy. The phase change of the obtained crystals was confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. It was shown that higher P123 concentration and higher reaction temperature favor the formation of vaterite in EAN. Unusual bagel-like vaterite was first obtained at 60 °C in the presence of 5 g/L P123 in EAN. Mineralization of CaCO₃ regulated by P123 in EAN is a simple, novel, and environment-friendly strategy for vaterite synthesis.     

Evolution Mechanism of Calcium Carbonate in Solution

Calcium carbonate was synthesized in a CaCl₂/NaCO₃ mixed solution by using ethylenedi-aminetetraacetic acid (EDTA) as an additive. The thermodynamics and kinetics analyses indicate that although the driving force of amorphous calcium carbonate (ACC) precipi-tation is always less than that of calcite and vaterite precipitation, the nucleation rate of ACC is greater than that of calcite and vaterite at the initial stage of the precipitation reaction. With the increasing incubation time, vaterite and calcite particles nucleate het-erogeneously by using the as-formed particles as active sites. Scanning electron microscopyimages indicate that the transformation mechanism of ACC and vaterite to calcite is the dissolution-recrystallisation reaction. The presence of EDTA not only improves the stabil-ities of ACC and vaterite, but also leads to forming enlongated, connected rhombohedralcalcite crystals after incubation 7 days in solutions. The ACC and vaterite are stabler in air than in solutions at room temperature, although the dissolution-recrystallisation reaction occurs on the surface.     

柠檬酸钠与碳酸钙晶型和形貌的控制

晶体的晶型和形貌是碳酸钙制备中的关键问题之一。 采用尿素水解均匀沉淀法来控制碳酸钙的晶型和形貌。 利用XRD和SEM等技术手段对CaCO₃晶体的结构和形貌进行了表征。 结果表明,高温条件下(90 ℃)水溶液中得到均匀的针状结构的文石晶体。 添加适量柠檬酸钠后,则得到的是特殊形貌的方解石晶体。 在乙醇/水混合溶剂中,柠檬酸钠对CaCO₃晶体的形貌也有重要影响,通过改变乙醇体积分数,得到了中空绒毛球状的球霰石。     

利用L-半胱氨酸自组装膜和混合溶剂协同作用手性拆分DL-谷氨酸

基于L-半胱氨酸(L-Cys)自组装膜(SAMs)在乙醇-水混合溶剂体系中对外消旋谷氨酸展现出的手性识别能力,在含60%(体积分数)乙醇的乙醇-水混合溶剂中,利用L-Cys SAMs对不同手性谷氨酸的选择性结晶作用,通过多次重结晶,分离出纯D-谷氨酸晶体,从而实现了对DL-谷氨酸的手性拆分.     

Controlling the polymorph and morphology of CaCO3 crystals using surfactant mixtures

Inspired by mineralization in biological organisms, fabrication of higher ordered CaCO(3) crystals modified by surfactants has received much attention. In our present work, mixed surfactants of hexadecyl(trimethyl)azanium bromide and sodium dodecyl sulfate were used to mediate the nucleation and growth of CaCO(3) crystals. When the concentration of sodium dodecyl sulfate in the solution is constant (0.1 mM), the polymorph of CaCO(3) crystals changed from pure vaterite to pure aragonite with increase of the ratio of hexadecyl(trimethyl)azanium bromide to sodium dodecyl sulfate. Various morphologies of vaterite and aragonite were obtained. Based on the time-resolved experiments, we suggest that the flower-like CaCO(3) formed via aggregation of hexagon-like vaterite induced by the surfactants. More importantly, we realized that a cluster-shaped morphology of aragonite was produced through the nucleation of aragonite at the surfaces of the hexagon-like vaterite.     

Controlled synthesis of calcium carbonate in a mixed aqueous solution of PSMA and CTAB

A mixed system of poly (styrene-alt-maleic acid) (PSMA) and cetyltrimethylammonium bromide (CTAB) was used as a very effective crystal growth modifier to direct the controlled synthesis of CaCO₃ crystals with various morphologies and polymorphs. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. It was found that the concentrations and relative ratios of PSMA and CTAB in the mixed aqueous solution were turned out to be important parameters for the morphology and polymorph of CaCO₃ crystals. Various morphologies of CaCO₃ crystals, such as hollow microsphere, peanut and so on, were produced depending on the concentrations and relative ratios of PSMA and CTAB. Moreover, the formation mechanisms of CaCO₃ crystals with different morphologies were discussed.     

Biomimetic growth of CaCO3 pancakes on the leaves of Epipremnum aureum

Rhombohedral, disk-like and pancake-like calcite crystals were synthesized in the different reaction condition via facial vegetal bio-templates, the leaves of Epipremnum aureum. The resultant crystals were characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The results showed that disk-like and pancakes calcite were obtained on the surface of Epipremnum aureum leaves in 50 mM CaCl₂ solution at starting pH values of 9.7 and 11.7, respectively. The dynamic process of formation of multiple crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. Moreover, it is found that the surface structure of the leave and starting pH value of reaction solution provide profound influence on the morphology of CaCO₃ crystals. This provides a facile and novel method to prepare hierarchical CaCO₃ crystals.     

Role of Polyelectrolytes in Crystallogenesis of Calcium Carbonate

The effects anionic polyelectrolytes, having various molecular weights and repeating unit structures, on the crystallization of calcium carbonate in supersaturated solutions are studied. The induction times of the crystals grown in the presence of the polymers were optically evaluated; X-ray diffraction and Scanning Electronic Microscopy (SEM) analyses were performed to determine, respectively, their crystalline structures and morphologies. The polyelectrolyte is found to lengthen the induction time and to reduce the size of CaCO₃ nanocrystallites, to an extent depending on the interaction efficiency between the polymer anionic repeating units and the calcium ions. Further, depending on their sizes and their crystalline structures (calcite, vaterite) the nanocrystallites aggregate and yield final calcium carbonate particles having various sizes and morphologies. The data indicate that nanocrystals having vaterite structure, as determined by X-ray analysis, give spherical CaCO₃ final particles, while nanocrystals having calcite structure lead to either acicular or flower shapes of CaCO₃ final particles.     

珍珠质基底上CaCO3晶体的仿生生长研究

珍珠质是一种典型的有机，无机层状复合材料．其中95％以上是文石（CaCO3的一种晶型1小板片，填充在板片之间的薄层有机基质仅占1％-5％。这种精细的组织结构不仅使珍珠质具有绚丽的光泽。还赋予珍珠质超乎寻常的强度和韧性（为合成CaCO3晶体的3000多倍）。虽然在珍珠质中有机质的含量不足5％．然而正是这些有机质对珍珠质的结构、性能、晶体取向等起着至关重要的调控作用。