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111.
Coarse-grained molecular dynamics simulations are used to investigate physical deposition behavior of charged amphiphlic diblock copolymers. The effects of solvent selectivity, charge distribution in amphiphlic diblock copolymers, and electric field strength on deposition conformations are studied qualitatively. Flat amphiphilic bilayers, which consist of hydrophilic monolayer and hydrophobic brush, are formed by physical deposition of charged amphiphlic diblock copolymers in nonselective solvents. For physically deposited amphiphlic diblock copolymers in selective solvents, amphiphilic bilayers consist of disc-shaped hydrophilic monolayers and hydrophobic nanospheres are found. This study sheds light on the formation of various amphiphlic diblock copolymer deposition conformations in different solvents and interaction mechanism of different components. Furthermore, the evolution of physical deposition process of charged amphiphlic diblock copolymers layer offers new insight to the controlling of amphiphilic bilayer thickness, hydrophobic nanosphere size, and interface property of depositional amphiphlic diblock copolymers. 相似文献
112.
本文提出一个直接积分结构动力学方程的高阶无条件稳定算法,并给出于利用复矩阵运算的实现方法。用本文算法,每个时间步中只需求解 N×N 阶复值线性代数方程组一次。此法的算法特性和作者以前发表的 DC 法(1990)完全相同,但缩短了计算时间并解除了对系统矩阵的若干限制(经典阻尼等)。通过几个算例对方法的精度作了考察。 相似文献
113.
Qian Li Wenxiang Zhu Chuncheng Li Guohu Guan Dong Zhang Yaonan Xiao Liuchun Zheng 《Journal of polymer science. Part A, Polymer chemistry》2013,51(6):1387-1397
Poly(isosorbide carbonate) (PIC) was synthesized by melt polycondensation of dimethyl carbonate (DMC) and isosorbide using lithium acetylacetonate (LiAcac) as the catalyst. The reaction conditions were optimized to achieve PIC with relatively high number‐average molecular weight (Mn) of 28,800 g/mol and isosorbide conversion of 95.2%. A series of poly(aliphatic diol‐co‐isosorbide carbonate)s (PAICs) were also synthesized by melt polycondensation of DMC with isosorbide and equimolar amounts of aliphatic diols (1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, and 1,4‐cyclohexane dimethanol) in the presence of LiAcac and the TiO2/SiO2‐based catalyst (TSP‐44). PAICs with Mn values ranging from 18,700 to 34,400 g/mol and polydispersities between 1.64 and 1.69 were obtained. The 13C NMR analysis revealed the random microstructure of PAICs. The differential scanning calorimetry results demonstrated that all the PAICs were amorphous with a unique Tg ranging from 46 to 88 °C. The dynamic analysis results showed that the incorporation of linear or cyclohexane structure changed the dynamic mechanical properties of PIC drastically. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
114.
研究了水/ 甲苯乳化液中二苯并噻吩( 硫芴) 在分散型钼酸、磷钼酸和四硫代钼酸铵催化剂存在下的加氢脱硫反应. 反应在高压釜中于340 ℃及三种不同的气氛即H2 , H2/H2O 和CO/H2O(CO 和H2O 经水煤气转换反应( WGSR) 产生原位氢) 的存在下进行. 用GC 和GCMS鉴定、分析了气体和液体产物的组成. 在此基础上,提出了包含直接氢解和加氢脱硫两个反应途径的硫芴加氢反应网络,并采用最优化法计算了反应网络的速率常数. 结果表明: 对所研究的9 个反应体系,反应网络的模型预测值与试验值十分吻合; 加氢路径比氢解路径至少快1 倍,硫芴的加氢比联苯的加氢快1 倍,部分加氢的中间产物1 ,2 ,3 ,4四氢硫芴和1 ,2 ,3 ,4 ,10,11六氢硫芴的氢解比硫芴直接氢解快10 倍以上; 对硫芴的加氢脱硫反应,在分散型钼存在下,原位产生的氢比加入的氢气更为有效. 相似文献
115.
Zhao W Chen C Ma W Zhao J Wang D Hidaka H Serpone N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(14):3292-3299
The titanium dioxide photocatalyst is employed to examine the influence of chemisorbed hexachloroplatinate(IV) anions (PtCl(6) (2-)) on the surface of P-25 TiO(2) particles on the photoinduced conversion of the azo dye Ethyl Orange (EO) in visible light-illuminated Pt(IV)/TiO(2) dispersions. Spin-trap electron spin resonance (ESR) spectral results, measurement of quantities of organoperoxides formed, total organic carbon (TOC) and chemical oxygen demand (COD(Cr)) assays, together with XPS evidence show that the self-sensitized transformation dynamics of the EO dye mediated by Pt(IV)/TiO(2) are much faster than those occurring on naked TiO(2) under otherwise identical conditions of visible light irradiation. X-ray photoelectron spectral data also show that under the experimental conditions used, no Pt(0) formed on the titania particles during visible light irradiation. We propose a reaction mechanism in which the more rapid conversion of EO in the presence of PtCl(6) (2-) is caused principally by photoexcitation of the dye and not by localized excitation of the tetrachloroplatinate(IV)/TiO(2) particles. 相似文献
116.
Photodegradation of dye pollutants on TiO<Subscript>2</Subscript> pillared bentonites under UV light irradiation 总被引:1,自引:0,他引:1
Jingyi?Li Chuncheng?Chen Jincai?ZhaoEmail author Huaiyong?Zhu Zhe?Ding 《中国科学B辑(英文版)》2002,45(4):445-448
TiO2 pillared bentonite samples dried under different conditions are used to degrade 2,4-dichlorophenol and orange II under UV
light irradiation. The supercritical dried sample exhibits a high activity for the photodegradation of 2,4-dichlorophenol
and orange II due to its structural features. TOC and COD are measured during the degradation of 2,4-dichlorophenol under
UV light irradiation using P25 and TiO2 pillared bentonite samples dried under different conditions. The clay-based catalysts can be readily separated by filtration
or sedimentation. 相似文献
117.
The stoichiometric terminations and nonstoichiometric terminations have been constructed for CaTiO3 (111) surface. The cleavage and surface energies, surface grand potential and surface electronic structure have been calculated for the two main classes of terminations using ab initio plane wave ultrasoft pseudopotential method based on Local Density Approximation (LDA). The results show that the stoichiometric terminations are unstable compared with the nonstoichiometric terminations and the polarity compensation achieved through the modification of the surface stoichiometry is more effective than that by the anomalous filling of the surface states. In the O and Ca chemical environments, only CaO2 and TiO terminations can be formed; the CaO3 and Ti terminations cannot be stabilized, even in very O-rich chemical environment. 相似文献
118.
119.
膨胀土是一种具有特殊工程性质的土,它对土木工程有着巨大的影响和危害。本文针对公路膨胀土路堤填料改良提出的PAS化学改性剂包边处理新方法,对其改性原理及其特殊的施工工艺做了详细介绍,并通过多项试验研究了改良前后膨胀土胀缩性、强度特性等方面的变化。研究表明,PAS生态改性处理膨胀土是一种有效的方法,经处理后的膨胀土胀缩性显著降低,强度和水稳定性得到大幅提高。且PAS不会改变原土壤植被育培能力,改性边坡可以结合植物固坡的方法进行生态防护。PAS改性处理与远距离运土路基填料置换相比,具有很大经济优势,特别是在高塑性膨胀土大量分布的地区,PAS改性剂处理膨胀土路基具有很好的推广价值。 相似文献
120.
We use Brownian dynamics (BD) simulations to investigate the formation and structural characteristics of the complex between a spherical polyelectrolyte brush (SPB) and oppositely charged surfactants. Increasing the amount of added surfactants leads to a collapsed conformation of the SPB and the number of adsorbed surfactants exhibits a linear dependence. Nevertheless, the surfactant uptake into the SPB does not increase with further addition of surfactants. It is found that the surfactant length has a strong influence on the SPB conformation and the adsorption properties of surfactant. Upon changing the surfactant length from 3 to 11, the SPB undergoes a swelling-deswelling-reswelling conformational transition. The brush deswelling is due to the increase in the surfactant uptake. The increasing size of adsorbed aggregates is a main reason for reswelling of the SPB. A non-linear relationship between the brush thickness and the grafting density is observed. Especially at intermediate grafting densities, increasing the number of grafted chains has a weak effect on the brush thickness. We also find that a completely collapsed brush conformation occurs at high surfactant/SPB charge ratios or large surfactant lengths, while the brush layer is in a partly collapsed or extended state at an intermediate charge ratio and surfactant length. 相似文献