平板狭缝中两嵌段共聚高分子微观相变的Monte Carlo模拟

采用改进的键长涨落空穴扩散算法对平板狭缝中的对称两嵌段共聚高分子熔体的微相分离形态、密度分布以及结构因子进行了MonteCarlo(MC)模拟 .模拟结果表明 :在不同性质壁面的平板狭缝中对称两嵌段共聚高分子熔体的微相结构都是层状的 ,但其取向由壁面性质决定 ,对称中性壁面形成垂直于壁面的层状结构 ,对称选择性吸引壁面以及非对称的选择性吸引和选择性排斥壁面组合导致平行于壁面的层状结构 ,而非对称的选择性吸引和中性壁面的组合形成的层状结构 ,在吸引壁一侧平行于壁面、在中性壁一侧则垂直于壁面 .对结构因子的计算表明对称体系微相结构主要取决于外场的对称性     

非对称两嵌段高分子在选择性壁面识别吸附的Monte Carlo模拟

采用自由空间的Monte Carlo（MC）方法研究了两嵌段非对称高分子在选择性壁面上的吸附与识别。研究表明;非对称嵌段高分子同对称嵌段高分子一样;在选择性壁面的吸附可分为吸附和识别两个过程。对高分子构型研究的结果发现;无论条纹宽度如何变化;高分子在垂直于z方向的均方回转半径总是小于其垂直另两方向的值。在条纹宽度一定的情况下;尾式构型比率随链节B与白色条纹壁面作用能Ψ ^B-white增加先增加然后趋于不变。在Ψ ^B-white不变的情况下;尾式构型比率则随条纹数的增加而增加。环式构型比率在条纹较宽时会随Ψ ^B-white有一小的下降趋势;而在条纹较窄时下降幅度较大。     

高分子构象模拟研究中的Monte Carlo方法

介绍了Monte Carlo方法及其特点,进而分析了Monte Carlo用于高分子模拟的优势,并描述了两类模拟模型。论文重点综述了近年来Monte Carlo方法在高分子构象模拟中的一些研究与应用,并展望了Monte Carlo方法在高分子构象模拟中的发展趋势和前景。     

共聚高分子吸附的Monte Carlo模拟

用MonteCarlo方法对选择性溶剂中两嵌段共聚高分子在固液界面的吸附进行了模拟 ,获得了吸附等温线以及吸附层厚度、链附着率、表面覆盖率、链节浓度分布等表征吸附层结构的信息 ,同时模拟获得了固液界面区吸附构型大小及分布等表征高分子构型的微观信息 ,考察了吸附性链节A所受的对比排斥能、链组成以及体相浓度等因素对这些参数的影响 .     

高分子抑制蛋白质聚集的动态Monte Carlo模拟

抑制聚集是蛋白质产品下游加工特别是制剂过程中的重要问题。本文采用动态Monte Carlo方法和二维晶格HP蛋白质模型,通过建立高分子-蛋白质复合物微观结构和蛋白质构象概率分布来研究高分子对蛋白质聚集行为的影响。结果表明,高分子的疏水性、分子量及其浓度对于蛋白质的聚集行为有显著的影响。当其疏水性适宜时,高分子可富集在蛋白表面疏水位点,强化蛋白质分子在水溶液中的分散,从而抑制聚集。高分子还可缠绕在蛋白质分子表面形成限制性空间从而稳定蛋白质的天然结构。     

Monte Carlo模拟对称型三嵌段共聚高分子的吸附

The adsorption behavior of symmetric triblock copolymers, Am/2BnAm/2, from a nonselective solvent at solid-liquid interface has been studied by Monte Carlo simulations on a simple lattice model. Either segment A or segment B is attractive, while the other is non-attractive to the surface. Influences of the adsorption energy,bulk concentration, chain composition and chain length on the microstructure of adsorbed layers are presented.The results show that the total surface coverage and the adsorption amount increases monotonically as the bulk concentration increases. The larger the adsorption energy and the higher the fraction of adsorbing segments, the higher the total surface coverage is exhibited. The product of surface coverage and the proportion of non-attractive segments are nearly independent of the chain length, and the logarithm of the adsorption amount is a linear function of the reciprocal of the reduced temperature. When the adsorption energy is larger, the adsorption amount exhibits a maximum as the fraction of adsorbing segment increases. The adsorption isotherms of copolymers with different length of non-attractive segments can be mapped onto a single curve under given adsorption energy. The adsorption layer thickness decreases as the adsorption energy and the fraction of adsorbing segments increases, but it increhses as the length of non-attractive segments increases. The tails mainly govern the adsorption layer thickness.     

无规共聚高分子溶液相平衡的Monte Carlo模拟

引　言近年来 ,随着计算机硬件能力的不断提高和新的模拟方法的不断涌现 ,对于高分子溶液的相平衡问题的计算机模拟研究取得了很大的进展 ,但大多将注意力放在如何改进模拟方法以获得更长的均聚高分子溶液的相平衡数据 ,以检验Ｆｌｏｒｙ -Ｈｕｇｇｉｎｓ理论、修正Ｆｒｅｅｄ理论等的有效性 .如Ｍａｄｄｅｎ等[1]曾利用蛇行法 (ｒｅｐｔａｔｉｏｎ)和伪动态模拟算法( ｐｓｅｕｄｏｋｉｎｅｔｉｃｓｉｍｕｌａｔｉｏｎａｌｇｏｒｉｔｈｍ)、Ｍａｃｋｉｅ等[2 ]在邻位数Ｚｎ=2 6的格子模型上用Ｇｉｂｂｓ系综法、Ｗｉｌｄｉｎｇ等[3]用键长涨…     

不同工艺嵌段共聚PP结构与性能研究

采用核磁共振碳谱、凝胶渗透色谱和动态力学等多种分析手段对北京燕化石油化工股份有限公司3种不同聚合工艺生产的嵌段共聚聚丙烯产品进行结构与性能研究,分析出不同聚合工艺生产的产品结构、性能的特点及差异,结构对性能的影响,为今后的生产及应用提供参考。     

Monte Carlo模拟随机共聚高分子在固/液界面的吸附行为

用Monte Carlo方法对无规共聚高分子在固液界面的吸附进行模拟,获得了固液界面区吸附链节的分布和吸附构型大小的分布等微观信息,以及总链节和吸附链节密度分布、链附着率、表面覆盖率、吸附量和吸附层厚度等宏观信息.考察了吸附性链节的对比吸附能ε_Aa和无规共聚高分子中吸附性链节比率f对它们的影响.结果表明,界面附近的高分子以尺寸较小的环式和卧式构型分布为主,而尾式构型分布较宽.当f增大时小环式构型迅速增加,卧式构型的分布则变宽.随着ε_Aa和f的增大,链附着率、表面覆盖率和吸附量等均随之增加,而吸附层厚度变薄.     

丙烯腈共聚物序列分布的Monte Carlo模拟

通过Monte Carlo方法，对不同共聚单体的聚丙烯腈组成进行了模拟。通过比较．与文献中提供的实验结果基本一致。同时模拟了衣康酸(1A)、丙烯酸(AA)、甲基丙烯酸(MAA)分别与丙烯腈(AN)在不同配比下共聚物的序列分布，结果表明：在Monte Carlo模型中，可以通过控制单体的配比来控制序列分布，而在实际的合成中，要获得均匀的序列结构，就可以通过降低第二单体投料比法或滴加单体法来实现。     

非选择性溶剂中两嵌段共聚物的吸附及Scheutjens-Fleer理论与Monte Carlo模拟的比较

Systematic comparison between computer simulation results and those predicted by Scheutjens-Fller(SF)self-consistent-field theory is presented for the adsorption of diblock copolymers from a non-selective solvent on attractive surface.It is shown that although SF is a mean-field theory,it can qualitatively describe the adsorption phenomena of diblock copolymers.However,systematic discrepancy between the theory and simulation still exists.The approximations inherited in the mean-field theory such as random mixing inside a layer and the allowance of direct back folding may be responsible to those deviations.     

水力旋流器分离过程的 Monte Carlo 模拟

根据颗粒在水力旋流器中的运动特点,提出了颗粒运动状态的交换构成三角马尔可夫链的观点,建立了水力旋流器分离过程的随机数学模型,并利用ＭｏｎｔｅＣａｒ┐ｌｏ方法进行了数值模拟,模拟程序中采用变参数设计,在输入一定的结构和工艺参数下,由计算机自动生成水力旋流器分离过程的级效率曲线,并给出总效率值;并计算了在不同容量下的模拟精度,结果表明样本容量越大,模拟精度越高     

水分子在高岭土中吸附特性的蒙特卡罗模拟研究(英文)

利用巨正则系综蒙特卡罗方法模拟高岭土对水分子的吸附特性。通过数值计算和实验分析,表征不同温度、压强及阳离子交换条件下高岭土的吸附机理。研究表明数值分析与实验结果吻合较好。温度和压强对高岭土的吸附性质有着明显影响。铝置换硅使得高岭土的活性有了大幅度提高。此外,不同阳离子的引入,不仅能平衡体系的电价,还能不同程度地改变高岭土的吸附特性。     

基于蒙特卡洛模拟法的钻井经济评价

对石油钻井进行投资决策时,要考虑各方面的风险因素和投资成本,为了降低石油钻井中的投资风险,在钻井之前就能预测到可能的成本,可以采用蒙特卡洛模拟法对钻井投资进行风险预估。本文通过对不同的地层分别运用蒙特卡洛模拟法,在不同的地层建立蒙特卡洛模的模型,并应用matlab模拟软件处理数据解释分析结果,最终得出钻井费用的预测值和误差,为投资决策提供依据。     

Monte Carlo simulation of polyampholyte-nanoparticle complexation

The complexation between a polyampholyte and a charged particle was investigated via Monte Carlo simulations on an off-lattice. The simulations revealed that there are three regions for the conformation of the complex formed between a positively charged particle and a polyampholyte chain. When the charge density and the size of the particle were small, the chain adsorbed on the particle surface maintained to a large extent its configuration from the bulk (spherical, dumb-bell, necklace or rod-like). By increasing the charge density and the particle size, the polyampholyte chain has collapsed on the surface. Further increases of the charge density and size of the particle caused a segregation of the beads of the sub-chains with mostly positive charges from those with mostly negative charges, those richer in positive charges being repelled by the particle. The simulation results are compared with some analytical results.     

双亲分子在油水界面的行为研究

A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In this model, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. The interfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with the increase of amphiphile concentration and the decrease with temperature.     

透明成核剂作用下的聚丙烯共聚物的等温结晶形态

利用偏光显微镜观察了聚丙烯共聚物（CPP）在透明成核剂TM-3作用下的等温结晶形态。结果表明：随结晶时间延长,CPP的球晶尺寸变大,形态也趋于完善;结晶温度并非越高越有利,CPP样品在140℃的结晶形态最好;球晶尺寸随TM-3含量提高而有所减小,但含有TM-3的CPP样品能够形成比CPP本体更大、更完善的球晶。TM-3在CPP结晶过程中提供了少量而有效的晶核,使丙烯链段能够附着在上面进行生长。     

Monte Carlo simulation of the compatibility of graft copolymer compatibilized two incompatible homopolymer blends: Effect of graft structure

Compatibility of graft copolymer compatibilized two incompatible homopolymer A and B blends was simulated by using Monte Carlo method in a two‐dimensional lattice model. The copolymers with various graft structures were introduced in order to study the effect of graft structure on the compatibility. Simulation results showed that incorporation of both A‐g‐B (A was backbone) and B‐g‐A (B was backbone) copolymers could much improve the compatibility of the blends. However, A‐g‐B copolymer was more effective to compatibilize the blend if homopolymer A formed dispersed phase. Furthermore, simulation results indicated that A‐g‐B copolymers tended to locate at the interface and anchor two immiscible components when the side chain is relatively long. However, most of A‐g‐B copolymers were likely to be dispersed into the dispersed homopolymer A phase domains if the side chains were relatively short. On the other hand, B‐g‐A copolymers tended to be dispersed into the matrix formed by homopolymer B. Moreover, it was found that more and more B‐g‐A copolymers were likely to form thin layers at the phase interface with decreasing the length of side chain. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007