氨基酸-表面活性剂体系合成CaCO_3晶体

以L-组氨酸和十二烷基苯磺酸钠(SDBS)作为CaCO3生长调节剂,用粉末X射线衍射、红外光谱测试技术对生成的CaCO3晶体进行了表征,扫描电子显微镜对生成的CaCO3晶体形貌进行了分析,研究了表面活性剂浓度、温度和溶剂的组成对CaCO3晶型和形状的影响。结果表明,在实验条件下表面活性剂的浓度对CaCO3晶型没有影响,但影响晶体的形状,温度和溶剂的组成对CaCO3晶型和晶体形状有很大的影响。     

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.     

丙烯酸聚乙二醇酯-甲基丙烯酸共聚物对CaCO_3微粒形貌的调控

研究了两种聚合物丙烯酸聚乙二醇酯 (PEGA)和丙烯酸聚乙二醇酯 -甲基丙烯酸共聚物 (PEGA PMAA)对CaCO3粒子生长的调控 .发现PEGA调控下得到CaCO3 片层状粒子的粒径比在纯水中的小 ,而PEGA PMAA调控下的粒子粒径较大 ,并且长成了奇特的花状形貌 .这说明PEGA在CaCO3 粒子生长过程中起了阻碍作用 ,而双亲水的PEGA PMAA则促进了CaCO3 粒子的生长 .     

醇-水混合溶剂中双亲水嵌段共聚物对CaCO3粒子形貌的调控

合成形态、大小及结构受到人为调控的无机材料是现代材料科学的一个重要研究方向, 通过生物模拟方法可望实现各类有机添加剂及模板对无机物形貌与结构的有效调控[1,2]. 近年来, 一类新型的无机晶体生长调控剂--双亲水嵌段共聚物[3]已成功地用于多种无机粒子形貌的有效调控. 双亲水嵌段共聚物由2个与无机表面亲和作用不同的亲水链段构成, 在其水溶液中, 已实现了具有一系列特殊形貌的碳酸钙[4~6]、磷酸钙[7]及硫酸钡[8]粒子的生物模拟合成. 人们已陆续报道了在多种有机添加剂及模板作用下典型的生物矿物CaCO3的生物模拟合成[9,10]. 我们曾系统地研究了水溶液中双亲水嵌段共聚物对CaCO3粒子形貌的调控作用[6],最近又在双亲水嵌段共聚物-表面活性剂混合溶液中合成出具有新颖形貌(如空壳状等)的CaCO3粒子[11]. 本文考察了醇-水混合溶剂中双亲水嵌段共聚物对CaCO3粒子形貌的调控作用, 初步揭示了溶剂特性对该调控作用的显著影响.     

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。     

水溶液体系中钐离子(III)对草酸钙结晶过程影响效应的研究

进行了水溶液体系中三价稀土离子(Sm3 )对草酸钙(CaC2O4)结晶过程影响效应的研究.采用微量热法、X射线衍射(XRD)以及扫描电镜(SEM)法,研究了Sm3 对草酸钙结晶过程动力学的影响效应及对草酸钙晶体晶型、形貌、尺寸的调控作用.微量热研究结果表明,Sm3 对草酸钙结晶过程的影响包括对晶体初期成核以及晶体生长过程的影响,在适宜的浓度(约2.50×10-5mol?L-1)下达到对晶体成核与生长的最佳抑制效果;XRD研究结果表明,Sm3 的加入有利于草酸钙二水合物(COD)的生成;SEM形貌研究表明,Sm3 对草酸钙晶体的形态、尺寸产生非常显著的调控作用.     

类胆碱离子液体中多级结构Bi_2S_3的形貌调控合成

本文通过简单温和的溶液合成方法,在类胆碱离子液体体系中制备了纳米线簇、绒球状、海胆状和纳米花状等不同形貌可控的Bi_2S_3纳米材料.通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和电子透射电镜(TEM)对样品的形貌与结构进行了分析表征.实验结果表明,IL/H_2O/PEG-200的比例在调控不同形貌的Bi_2S_3形成过程中起到了决定性的作用.同时也研究了离子液体阳离子烷基侧链的长度和反应时间对样品形貌形成过程的影响.基于晶体分裂和溶解-重结晶过程对不同形貌Bi_2S_3样品的形成机理进行了分析讨论.     

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30～40μm;(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10h获得的晶片结构呈规则的六边形,片尺寸约为10～20μm,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。     

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。     

{110}晶面取向Ag3PO4多面体的水热制备及可见光催化活性

采用简易水热法在聚乙二醇-6000 (PEG-6000)辅助下合成了Ag₃PO₄多面体.系统考察了水热反应温度、时间及PEG-6000用量对产物形貌和结构的影响.通过X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis DRS)和荧光(PL)光谱等测试手段对光催化剂进行了表征.结果表明,适宜的水热温度及PEG-6000用量是制备具有{110}活性晶面取向Ag₃PO₄多面体的必要条件,该多面体通过纳米颗粒的Ostwald熟化效应生长而成.可见光催化降解罗丹明B (RhB)的实验表明,该Ag₃PO₄多面体活性明显优于其它水热条件下所制备的非{110}取向晶面样品和离子交换法所得纳米颗粒,其降解反应速率常数(k)为离子交换法所得Ag₃PO₄纳米颗粒的8.3倍.总有机碳含量(TOC)及循环实验证明,该Ag₃PO₄多面体可以有效地矿化RhB并保持较好的循环稳定性.活性自由基捕获实验表明,空穴(h⁺)和羟基自由基(·OH)是光催化氧化的主要活性物种.结合活性物种的氧化还原电位以及Ag₃PO₄的能带结构分析,提出了催化反应界面光生电子-空穴(e^--h⁺)对的分离及转移机制.     

核壳结构聚丙烯酸酯抗冲改性剂的合成及粒径控制

采用预乳化多步种子乳液聚合法合成聚丙烯酸酯类聚合物(ACR)胶乳,实验得出种子乳液用量与聚丙烯酸丁酯粒径之间的关系,实现对胶乳粒子粒径的控制;对反应中影响粒子粒径的因素做了分析,以此确定最佳反应条件为:温度为65℃;乳化剂:十二烷基硫酸钠和聚氧乙烯基醚硫酸钠摩尔比为4/3,乳化剂用量为0.9％,单体固含量30％～37％...     

两种聚天冬氨酸接枝共聚物的制备及其阻垢性能

以马来酸酐、尿素、二乙烯三胺、1-氨基-2-萘酚-4-磺酸等为原料,合成了聚天冬氨酸/二乙烯三胺(PASP/DETA)和聚天冬氨酸/1-氨基-2-萘酚-4-磺酸接枝共聚物(PASP/1,2,4);采用红外光谱仪分析了产物的化学结构,并测定了其对工业用水的阻垢性能.结果表明,PASP/DETA对Ca3(PO4)2具有很好的阻垢性能,PASP/1,2,4对CaCO3具有很好的阻垢性能;当二者按PASP/DETA浓度5mg/L、PASP/1,2,4浓度1.5mg/L复配使用时,对CaCO3的阻垢率可达95.4%,对Ca3(PO4)2的阻垢率可达95.2%.     

A bio-inspired approach to the synthesis of CaCO3 spherical assemblies in a soluble ternary-additive system

Two different soluble polymers, poly(ethylene glycol) (PEG) and poly(methacrylic acid) (PMAA), with individual functions were successfully employed in combination with a third additive, sodium dodecyl sulfate (SDS), in one system, and spherical assemblies (e.g., hollow spheres) with multiscale constructs of CaCO3 were obtained. The variation of polymer concentration drastically changed both the morphology and polymorph of the produced CaCO3 crystals due to the corresponding transformation of the micelle structure. This study suggests that noncovalent interaction and cooperation between soluble macromolecules play key roles in controlling the growth of biominerals. The results also suggest a novel and facile route toward biomimetic inorganic synthesis.     

Crystallization and aggregation behaviors of calcium carbonate in the presence of poly(vinylpyrrolidone) and sodium dodecyl sulfate

An anionic surfactant interacts strongly with a polymer molecule to form a self-assembled structure, due to the attractive force of the hydrophobic association and electrostatic repulsion. In this crystallization medium, the surfactant-stabilized inorganic particles adsorbed on the polymer chains, as well as the bridging effect of polymer molecules, controlled the aggregation behavior of colloidal particles. In this presentation, the spontaneous precipitation of calcium carbonate (CaCO3) was conducted from the aqueous systems containing a water-soluble polymer (poly(vinylpyrrolidone), PVP) and an anionic surfactant (sodium dodecyl sulfate, SDS). When the SDS concentrations were lower than the onset of interaction between PVP and SDS, the precipitated CaCO3 crystals were typically hexahedron-shaped calcite; the increasing SDS concentration caused the morphologies of CaCO3 aggregates to change from the flower-shaped calcite to hollow spherical calcite, then to solid spherical vaterite. These results indicate that the self-organized configurations of the polymer/surfactant supramolecules dominate the morphologies of CaCO3 aggregates, implying that this simple and versatile method expands the morphological investigation of the mineralization process.     

Impacts of PEG-6000 pretreatment for barley (Hordeum vulgare L.) seeds on the effect of their mature embryo in vitro culture and primary investigation on its physiological mechanism

In this paper, we studied polyetheneglycol (PEG) pretreatment effect on the mature embryo culture in vitro by using barley (Hordeum vulgare L.) seeds. Meanwhile, we analyzed and assayed its mineral element and endogenous hormone level. The experimental results were as follows: (1) PEG-6000 imbibition could obviously slow down the water timecourse absorbed by barley seeds; (2) 10% PEG-6000 treatment of barley seeds for 3 h had a positive effect on germination in vitro and callus induction of the barley seed mature embryos; (3) 10% PEG-6000 treatment inhibited soluble leakage from the seeds; (4) N leakage was mainly from the endosperms, Mn2+ leakage from embryos; (5) PEG-6000 treatment changed greatly the hormone level (ABA, IAA, GAs), which influenced the percentage of plantlets from the mature embryo callus. The results can provide some clues to scientific sowing of crop seeds, pretreatment for the purpose of uniform seedlings, and the explant response quality in plant tissue culture.     

LaCoO3对H2S选择氧化性能的影响

使用溶胶-凝胶法制备了LaCoO₃催化剂,采用XRD、BET和XPS等方式对催化剂进行了表征,考察了该催化剂制备过程中煅烧温度、表面活性剂PEG-6000和PEG-20000含量对其H₂S选择氧化制硫磺反应催化活性的影响。结果表明,表面活性剂PEG-6000及PEG-20000的添加能明显提高LaCoO₃的催化活性。0.02 mol La（NO₃）₃+0.02mol Co（NO₃）₂溶液中添加0.30 g PEG-20000、煅烧温度为650℃时所制备的LaCoO₃催化活性最好;在最佳反应温度260℃下,H₂S的转化率达到96.10%,硫选择性为93.77%。     

超细CaCO_3的粒子尺寸对PP结晶行为的影响

The effects of CaCO3 on the crystallization behavior of polypropylene (PP) were studied by means of DSC and WAXD.The average sizes of the CaCO3 powders used were 0.1μm (UC) and 0.5μm (GC),respectively.The PP/CaCO3 composites at compositions of 1phr and 10 phr were investigated.The results showed that the addition of CaCO3 reduced the supercooling,the rate of nucleation and the overall rate of crystallization (except for the 10phr UC/PP sample).The crystallinity of PP was increased and the size distribution of the crystallites of α-PP was broadened.On the other hand,the crystallization rate of 10phr UC/PP is 1.5 times higher than that of neat PP.It has an overall rate of crystallization 2 times as much as that of the neat PP and has the maximum crystallinity.The sizes of crystallites and the unit cell parameters of α-PP were varied by the addition of CaCO3.β-PP was formed by addition of GC and was not detected by addition of UC.The differences of crystallization behaviors of PP might be attributed to the combined effects of the content and size of CaCO3 filled.     

超重力环境中合成微细晶须碳酸钙及其表征

Ultra-fine whiskers of calcium carbonate were successfully synthesized by reactive precipitation in highgravity field generated by the rotating packed bed（RPB）. In the experiment Ca（OH）2 and CO2 were as reactants and H3PO4 was used as the morphology-control additive. Synthesizing the same amount of CaCO3 whiskers,the needed carbonation time in the high-gravity field is 1/36-1/18 of that by the traditional technology reported in the literature. The ultra-fine CaCO3 whiskers can be synthesized and well-controlled under the following conditions:the volumetric flow rate of gas 100-300 L/h and that of liquid 600-1000 L/h,rotating speed of RPB 600-1200 r/min,reaction temperature between 40-80℃ and concentration of H3PO4 5.0%-30%. The calcium carbonate whiskers have the mean shaft diameter of 80-250 nm and the average aspect ratio of 10-25 with the narrow distribution of both the mean shaft diameter and the aspect ratio. The properties of the product are characterized by means of TEM,electron diffraction,XRD,TG-DTA and elementary analysis. Electron diffraction analysis shows that the synthesized calcium carbonate whiskers have crystalline structure,while XRD analysis indicates that aragonite structure accounts for 97.77% in content of the final CaCO3 whisker product. And TG-DTA analysis shows that the obtained product decomposes at 423℃,which is 402℃ lower than that of the CaCO3 obtained in the normal gravity.     

Influence of sodium dodecyl sulfate and static magnetic field on the properties of freshly precipitated calcium carbonate

Properties of calcium carbonate precipitated from aqueous solutions of CaCl(2) and Na(2)CO(3) in the presence of sodium dodecyl sulfate (SDS) and S-S 0.1 T magnetic field (MF) were studied. The nucleation and precipitation processes of CaCO(3) were investigated by pH and zeta potential measurements at 20 +/- 1 degrees C up to 2 h after mixing the solutions. Also the amounts of calcium carbonate deposited on the glass surfaces and its structure were examined. It was found that SDS influences the kinetics of precipitation, crystallographic forms, and crystal size of CaCO(3). The SDS effects are more pronounced in MF presence. A small amount of SDS accelerates transformation of vaterite into calcite, whereas increasing surfactant concentration moderates such a transformation. On the other hand, in all the systems, MF in the presence of SDS causes a slower transformation of vaterite into calcite. These effects are reflected in pH and zeta potential changes, although there is no clear dependence between the SDS amount present during the precipitation and changes of the parameters investigated. It seems that MF effect is most significant at a defined optimal SDS concentration. The results, however, do not allow suggestion of any detailed mechanism of the field interaction.     

The magnetic field influence on the polymorph composition of CaCO3 precipitated from carbonized aqueous solutions

One of the most debated effects the magnetic fields exert on aqueous solutions and dispersions is their influence on the crystal structure of the main scale component, CaCO3. This study presents the results of an experimental program performed to quantitatively evaluate influence of the key magnetic treatment parameters--magnetic induction, exposure time, and fluid velocity--on the polymorph composition of CaCO3, precipitated from carbonized aqueous solutions. The results show that magnetic treatment favored the precipitation of aragonite. The key treatment parameters affecting the aragonite content were the magnetic induction and the exposure time, while the fluid velocity exerted no significant influence. The magnetic field has no significant influence on the zeta potential of the precipitated particles in any stage of the treatment. These experimental findings indicate that the magnetic field influence on the crystal structure of CaCO3 cannot be attributed to the magnetohydrodynamic influence on the charge distribution within the electrical double layer of the forming crystallites. The results rather suggest that the magnetic fields influence the CaCO3 polymorph phase equilibrium either by influencing the CO2/water interface or through the hydration of CO3(2-) ions prior to the formation of stable crystal nuclei in the solution.