有机膦系抑制方解石阶梯面生长的分子动力学研究

有机膦系化合物是工业冷却水系统中常用阻垢剂,对有机膦酸阻垢剂的阻垢性能及机理进行研究,能为新型阻垢剂开发应用提供合理的理论依据。根据周期性键链（PBC）理论模型,运用分子动力学方法（MD）,模拟了工业冷却水循环过程中5种有机膦阻垢剂与方解石4种阶梯面的相互作用机理。结果表明,有机膦酸分子与方解石（104）4个阶梯面的结合能均为负值,相互作用为放热过程,阻垢剂分子对方解石（104）阶梯面的生长具有良好的抑制作用。通过计算结合能,得出阻垢剂分子的吸附能力由强到弱依次为HDTMP、EDTMP、ATMP、NDP、AMP;同时观察到有机膦酸分子主要吸附在晶面的活性生长点,即阶梯面的终端拐角位置与阶梯拐点位置,占据了晶面上结晶的活性位置,抑制了晶面的进一步生长。根据有机膦酸与阶梯面结合能数据,得到4种终端阶梯面的吸附能力由强到弱依次为CO₃-CO₃、CO₃-Ca、Ca-CO₃、Ca-Ca,即稳定性越强则吸附能力越弱。     

三种有机膦酸阻垢剂对碳酸钙晶面吸附作用的分子动力学研究

结合多晶硅实际生产工艺,采用分子动力学模拟方法研究了3种典型有机膦酸阻垢剂NTMP、EDTMP和DTPMP与碳酸钙晶面的吸附作用。结果表明:3种有机膦酸阻垢剂分子能够自发吸附在碳酸钙晶面上,吸附能为负值,吸附过程为放热过程;对碳酸钙(110)面的吸附作用强于(104)面,会优先吸附在(110)面上;吸附能主要由静电作用能和范德华作用能组成,其中静电作用能远大于范德华作用能,占主导作用;对方解石晶面吸附作用的顺序是DTPMPEDTMPNTMP,对碳酸钙垢阻垢作用顺序是DTPMPEDTMPNTMP,吸附作用越大,对碳酸钙垢抑制作用越强。     

低分子质量羧酸聚合物阻垢剂效果评价和理论研究

以低分子质量聚丙烯酸(PAA)和聚环氧琥珀酸(PESA)为研究对象，通过静态阻垢实验和分散能力测试评价其对碳酸钙垢的抑制效果，并结合量子化学计算及分子动力学模拟深入研究羧酸类分子结构与阻垢效果之间的关系。结果表明，两种低分子质量羧酸聚合物阻垢剂抑制了垢晶体的正常生长，引发了晶体畸变，且主要作用于方解石晶体的(104)和(110)晶面。和PESA相比，PAA具有更多的羧酸基团和负电荷，使其与Ca²⁺之间的结合能增大，从而具备更高的阻垢效率。此外，温度对PAA阻垢能力的影响大于PESA。     

乙烷-1,1-二膦酸与乙烷-1,2-二膦酸阻垢效能差异的微观机理研究

基于半经验分子轨道理论 ,通过计算分析了乙烷 1,1 二膦酸 (1,1 EDPA)和乙烷 1,2 二膦酸 (1,2 EDPA)分子的空间电荷分布、几何构型以及有机分子与晶体表面的相互作用 ,初步探讨了分子结构与其阻垢性能之间的关系。计算结果显示 ,1,1 EDPA分子中膦酸基的氧离子呈负电性 ,这使得膦酸基易与晶面上的钙离子发生静电交互作用。 1,1 EDPA分子中两个膦氧离子间距为 4 0 9× 10 -10 m ,这与方解石 { 10 4} { 10 2 }晶面钙离子间距互相匹配 ,因而加强了阻垢剂分子与特定晶面的结合 ,抑制了晶面的进一步生长发育。而 1,2 EDPA的分子构型不具备与方解石晶面钙离子匹配的特征 ,因而其对于方解石晶体的阻垢特性劣于 1,1 EDPA     

乙酸乙酯与ε-CL-20不同晶面的微观作用机制

采用色散校正的密度泛函方法、分子动力学和Monte Carlo模拟技术,对乙酸乙酯(EA)与六硝基六氮杂异戊兹烷(ε-CL-20)晶面的微观作用机制进行研究,分析了晶面特性和EA与各晶面的相互作用。结果表明,附着能模型预测真空中ε-CL-20有6个晶面,其表面积(1 0 1)>(1 1-1)>(1 1 0)>(1 0-1)>(0 1 1)>(0 0 2),粗糙度(1 0-1)>(1 1-1)>(0 1 1)>(1 0 1)>(1 1 0)>(0 0 2)。带隙最大的两个晶面为(0 0 2)(3.522eV)和(1 0 1)(3.512eV),而(1 1 0)(3.179eV)和(1 1-1)(3.193eV)的带隙最小。EA分子通过C—H…O弱氢键、范德华力等相互作用与ε-CL-20晶面上的活性位点结合。正的吸附热和负的吸附能表明EA分子在所有晶面上的吸附均为放热过程。EA分子通过(1 1-1)面上的袋状空隙进入晶格,形成最厚的界面溶剂层(约10?)和最大的结合能(291.93kJ/mol)。该晶面吸附EA分子的个数和吸附能的...     

2-硝亚胺基-5-硝基-六氢化-1,3,5-三嗪的晶体形貌预测

利用Materials studio 5.0软件包中的Morphology模块所含的BFDH、Growth Morphology和Equilibrium Morphology三种方法计算了2-硝亚胺基-5-硝基-六氢化-1,3,5-三嗪的晶体形貌,得到了特定的晶面的面积、表面能、附着能及晶面的相对生长速率参数,确定了形态学上重要的生长晶面。各晶面的结构分析表明,(011)和(021)为强极性晶面,(110)、(200)为极性晶面,(001)和(20-1)为弱极性晶面。据此可以预测,在强极性的质子溶剂中,(011)和(021)为形态学上的重要晶面,(110)、(200)、(001)和(20-1)晶面的显露可能增加。在非极性溶剂中,情况可能相反。     

不同(001)晶面暴露比例的锐钛矿二氧化钛的可控合成研究

使用P25(Degussa)二氧化钛作为钛源,二乙醇胺作为形貌控制剂,通过两步水热法制备了含有不同比例的高能(001)晶面的锐钛矿二氧化钛。实验探究了水热温度、二乙醇胺的用量对产物(001)晶面暴露比例的影响。用X-射线衍射仪(XRD)、扫描电镜(SEM)对所制备含有不同比例(001)晶面产物的物相和形貌进行表征分析,计算了不同产物含有的(001)晶面的比例。实验结果表明,二乙醇胺的用量对(001)晶面的暴露比例有很大影响,增加二乙醇胺的用量,产物的(001)面增多。通过控制反应中二乙醇胺的用量,制备出(001)晶面暴露比例为15%~80%的产物。     

含氟聚合物包覆铝粉的分子动力学计算

利用分子动力学模拟研究了不同含氟聚合物(F2311、F2603及F2462)、十二烷基苯磺酸钠(SDBS)与Al2O3(001)晶面的相互作用以及SDBS与3种含氟聚合物的相互作用,进一步利用分子动力学计算了O2分子在不同构型的3种含氟聚合物膜中的扩散速率。以F2311为例,计算了不同分子链个数、温度和不同聚合度条件下O2分子在F2311膜中的扩散速率。结果表明,F2311、F2603及F2462与Al2O3(0 0 1)晶面的结合能分别为1 798.24、3 817.39及1 047.22kJ/mol;SDBS与Al2O3(0 0 1)晶面的结合能显著大于含氟聚合物与Al2O3(0 0 1)晶面的结合能,并随着SDBS个数的增加而增大;F2311、F2603及F2462与SDBS的结合能分别为1 218.97、1 243.05及1 338.06kJ/mol;O2在含氟聚合物膜中的扩散速率受聚合物种类及构型影响,O2在F2311膜中的扩散速率随着F2311分子链个数及聚合度的增加而减小,随着温度的升高而增大。     

热处理温度对高强涤纶工业丝结晶与取向性能的影响

加工过程中的热处理对纤维的聚集态结构变化具有重要的影响。采用二维X射线衍射仪研究了高强涤纶工业丝分别经过25,75,125,175,225℃温度热处理后其结晶度和晶区取向度的变化。结果表明:在较低的热处理温度区域(25～75℃),随着热处理温度升高,高强涤纶工业丝的非晶区分子链段开始活动,晶区结构变得松散,结晶度下降,进一步升高热处理温度至125℃时,纤维晶区发生重结晶现象,结晶度略微增长,而热处理温度升高至175～225℃时,纤维逐渐熔融,结晶度显著下降;随着热处理温度升高,高强涤纶工业丝(010)晶面和(100)晶面的晶区取向度降低,(-110)晶面的晶区取向度增加,但纤维的晶区总取向度随热处理温度的升高而增加,主要是由(-110)晶面的晶区取向度增加导致。     

曹雨微[1],2,刘远2,孔会民1,2,岳萍2,唐大才2,林彦军1,[3]

以MgCl2为晶面调控剂，利用水热法对氢氧化镁（MH）的（001）晶面选择性生长进行调控，研究了晶面调控剂浓度、反应温度、反应时间等因素对MH颗粒的溶解和结晶作用。调控后产品各晶面的XRD衍射峰强度I001/I101和I001/I110较原料分别提高了214.30%和307.45%，百吨级中试产品的I001/I101和I001/I110较原料分别提高了84.08%和112.99%。采用XRD、FE-SEM、TEM、FTIR、粒度分析仪对MH产品的形貌、结构进行了表征，并对调控机理进行了研究。结果表明，MgCl2可以在水热体系中促进MH的（001）晶面选择性生长。一方面，MgCl2作为强酸弱碱盐降低了体系pH值，同时Cl－可以通过电荷中和效应使MH发生进一步加速溶解。另一方面，MgCl2提供的Cl－作用于MH的结晶过程，通过促进MH边缘生长，强化了（001）晶面的生长。     

磁处理对水溶液及CaCO3颗粒物理化学性质的影响

通过纯水及水溶液表面张力的变化,解释了磁处理对其物理化学性质的影响。结果表明,经磁处理后,纯水及水溶液的表面张力均呈下降趋势;同时,对磁处理前后的模拟水中形成的CaCO3颗粒进行X-射线衍射分析(XRD)、傅里叶变换红外分析(FTIR)及扫描电镜分析(SEM)。结果表明,模拟水未经磁处理时,生成CaCO3的晶型主要为立方形和菱形的方解石型,而经磁处理后生成的CaCO3晶型主要为偏三角面体晶形和玫瑰花形的球霰石型,同时存在少量方解石型。     

不同晶型CaCO3表面改性及CaCO3/PDMS超疏水涂层的制备

利用硬脂酸钠(NaSt)和油酸钠(NaOL)对文石型和方解石型两种CaCO₃粉体进行表面改性，将改性的CaCO₃粉体与聚二甲基硅氧烷(PDMS)共混，喷涂得到了CaCO₃/PDMS基超疏水涂层。采用XRD、SEM、接触角测量仪对改性CaCO₃粉体及超疏水涂层进行测试，考察了不同晶型CaCO₃用量对涂层疏水性能的影响，并对超疏水涂层的自清洁性及稳定性进行了评价。结果表明，当NaSt和NaOL用量分别为反应体系CaCO₃理论生成质量的5%时，CaCO₃粉体改性效果最好，所制备的CaCO₃/PDMS涂层疏水性最佳。当CaCO₃和PDMS质量比为1.5∶1时，CaCO₃/PDMS涂层接触角>150°，具有超疏水性。玻璃板涂层表面的亚甲基蓝污染物可以完全随着液滴被冲走，没有残留，且经过500 m L流速5 m/s的水流冲击，接触角仍达140°以上。     

The role of two different internal donors (phthalate and 1,3‐diether) on the formation of surface structure in MgCl2‐supported Ziegler–Natta catalysts and their catalytic performance of propylene polymerization

The role of two different internal donors [a phthalate (diisobutylphthalate) and a 1,3‐diether (2,2‐diisobutyl‐1,3‐dimethoxypropane)] on the formation of surface structure in MgCl₂‐supported Ziegler–Natta catalysts and their catalytic performance of propylene polymerization was investigated by comparing and correlating the catalyst structures and the polymerization characteristics. In the catalyst formation, the 1,3‐diether had better affinity for the MgCl₂ surface than the phthalate and the 1,3‐diether generated the (110) surface more than the (104) surface while the phthalate generated both the (110) and (104) surfaces of MgCl₂. With both donors introduced, the (110) and (104) surfaces were generated simultaneously, although the (110) surface was dominant due to the higher affinity via the 1,3‐diether. In addition, it seemed probable that the active sites formed on the (110) plane showed isospecific characteristics in the presence of a donor while those formed on the (104) plane could be isospecific regardless of a donor. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40536.     

Low-energy structures of clusters supported on metal fcc(110) surfaces

ABSTRACT: The low-energy structures (LESs) of adatom clusters on a series of metal face-centered cubic (fcc) (110) surfaces are systematically studied by the genetic algorithm, and a simplified model based on the atomic interactions is developed to explain the LESs. Two different kinds of LES group mainly caused by the different next nearest-neighbor (NNN) adatom-adatom interaction are distinguished, although the NNN atomic interaction is much weaker than the nearest-neighbor interaction. For a repulsive NNN atomic interaction, only the linear chain is included in the LES group. However, for an attractive one, type of structure in the LES group is various and replace gradually one by one with cluster size increasing. Based on our model, we also predict the shape feature of the large cluster which is found to be related closely to the ratio of NN and NNN bond energies, and discuss the surface reconstruction in the view of atomic interaction. The results are in accordance with the experimental observations.PACS: 68.43.Hn; 68.43.Fg.     

A mechanistic growth model for inorganic crystals: Solid‐state interactions

Growth shapes of inorganic crystalline solids govern material properties such as catalytic activity and selectivity, solar cell efficiency, and so forth. A systematic understanding of the crystal growth process and the solid‐state interactions within inorganic crystals should help to engineer crystal shapes. A general model that identifies periodic bond chains in inorganic crystals while accounting for the long‐range electrostatic interactions is presented. The variation in the electronic structure and the partial charges of growth units on the inorganic crystal surfaces has been captured using the bond valence model. The electrostatic interaction energies in the kink sites of inorganic crystals were calculated using a space partitioning method that is computationally efficient. This model provides a quantitative explanation for the asymmetric growth spirals formed on the surface of calcite. This methodology for studying solid‐state interactions can be used with a mechanistic growth model to predict the morphology of a wide variety of inorganic crystals. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3707–3719, 2014     

电化学水处理中碳酸钙结晶形态的研究

研究在电化学水处理中，电场对CaCO3结晶形态的影响。正常情况下， CaCO3形成稳定方解石型，其晶型通常为排列整齐、结构致密、质地坚硬的方解石型，难以去除。但在电场效应作用下，电流为0．3 A、极板间距为50 mm时，电场力能有效地促使CaCO3结晶形式转变为较为疏松的纹石型和球霰石型晶体，使其不容易附着在管道壁上且便于剥离去除。     

碳酸钙在流动过冷沸腾条件下的结垢机理研究

Fouling of heat transfer surfaces during subcooled flow boiling is a frequent engineering problem in process industries. It has been generally observed that the deposits in such industrial systems consist mainly of calcium carbonate （CaCO3）, which has inverse solubility characteristics. This investigation focused on the mechanism to control deposition and the morphology of crystalline deposits. A series of experiments were carried out at different surface and bulk temperatures, fluid velocities and salt ion concentrations. It is shown that the deposition rate is controlled by different mechanism in the range of experimental parameters, depending on salt ion concentration. At higher ion concentration, the fouling rate increases linearly with surface temperature and the effect of flow velocity on deposition rate is quite strong, suggesting that mass diffusion controls the fouling process. On the contrary, at lower ion concentration, the fouling rate increases exponentially with surface temperature and is independent of the velocity, illustrating that surface reaction controls the fouling process. By analysis of the morphology of scale, two types of crystal （calcite and aragonite） are formed. The lower the temperature and ion concentration, the longer the induction period and the higher the percentage of calcite nreciDitated.     

Spectroscopic study of carbon monoxide and sodium coadsorption on Ni(100)

The coadsorption of carbon monoxide and sodium on Ni(100) single crystal surfaces has been studied by using TPD, XPS and HREELS. Sodium binds to nickel forming a monolayer that desorbs through a complex process, most probably involving cluster formation. Further exposure to sodium results in the condensation of Na multilayers that desorb with an activation energy of 17.5 kcal/mole. CO coadsorption with submonolayer coverages of sodium displays quite complicated TPD and HREELS spectra. It is clear, however, that there are at least two kinds of interactions between CO and Na. A short range interaction is manifested by higher CO binding energies, lower C-O stretching frequencies, and perhaps even direct Na-O interaction. We propose a tilted bonding configuration in this case. There is also longer range effects as seen at low sodium coverages by more subtle changes in desorption activation energies and in vibrational frequencies.