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.     

多分散高分子在固液界面吸附层厚度的Monte Carlo模拟

在格子模型基础上用Monte Carlo方法模拟研究了多分散高分子在固液界面的吸附行为,重点考察了平均分布和正态分布两种不同链长分布形式的高分子在固液界面吸附层厚度的分布规律,模拟结果与概率统计模型计算的吸附层厚度分布趋势一致。随着系统温度升高,高分子链节热运动加剧,吸附层厚度的极值增大,大吸附层厚度的密度也有所增加。而链节吸附作用能的增大能显著压缩吸附层厚度,导致吸附层厚度极值分布前移,但固液吸附界面的表面覆盖率显著增大。高分子链长的分布形式对吸附层厚度有着显著的影响,平均分布的高分子体系对温度和链节吸附能以及高分子浓度的变化比较敏感。     

固液界面高分子吸附研究(Ⅰ)──模型的建立和检验

从常用密堆积格子模型导出了高分子溶液中自由高分子链节的几率表达式,在此基础上,通过类比的方法,建立了固液界面层中自由高分子链节的几率表达式,与DiMarzio-Rubin的高分子统计矩阵方法相结合,从而建立了基于密堆积格子的固液界面吸附模型．模型预测的高分子在界面层中的浓度分布与MC计算机模拟结果进行了比较,表明基于RevisedFreed和Guggenheim模型的固液界面吸附模型的计算结果比基于Flory-Huggins理论的模型计算结果,更接近于MC模拟值．     

固液界面高分子吸附研究(Ⅰ)──模型的建立和检验

从常用密堆积格子模型导出了高分子溶液中自由高分子链节的几率表达式，在此基础上，通过类比的方法，建立了固液界面层中自由高分子链节的几率表达式，与DiMarzio-Rubin的高分子统计矩阵方法相结合，从而建立了基于密堆积格子的固液界面吸附模型．模型预测的高分子在界面层中的浓度分布与MC计算机模拟结果进行了比较，表明基于RevisedFreed和Guggenheim模型的固液界面吸附模型的计算结果比基于Flory-Huggins理论的模型计算结果，更接近于MC模拟值．     

固液界面高分子吸附研究(Ⅱ)──高分子在界面的吸附

用本文（I）报建立的高分子吸附模型,计算了高分子在界面区的浓度分布、高分子吸附层的厚度、吸附量、不同构型的链段长度及其分布等微观结构,考察了体相高分子浓度、高分子──溶剂相互作用参数、吸附能参数、高分子链长等对高分子吸附行为的影响．     

固液界面高分子吸附研究(Ⅱ)──高分子在界面的吸附

用本文（I）报建立的高分子吸附模型,计算了高分子在界面区的浓度分布、高分子吸附层的厚度、吸附量、不同构型的链段长度及其分布等微观结构,考察了体相高分子浓度、高分子──溶剂相互作用参数、吸附能参数、高分子链长等对高分子吸附行为的影响．     

固液界面多分散高分子吸附

采用构作配分函数而后求极值的方法,将Scheutjens-Fleer模型推广到多分散高分子吸附情形,并采用适当的计算方法,解决了长期以来人们难以解决的多分散高分子模型计算上的困难,研究了固液界面区域多分散高分子的微观吸附行为、多分散指数对吸附层性质的影响以及各种微观构象的链段大小的几率分布.结果表明,相对分子质量大的高分子优先吸附于界面,多分散指数对吸附行为具有较大影响.     

链状分子在固体表面吸附的Monte Carlo模拟

用Ｍｏｎｔｅ Ｃａｒｌｏ方法模拟研究了链状分子在固体表面的吸附行为，考察了分子间相互作用能、体相浓度、吸附能及链长对链状分子在固体表面的吸附及构型分布的影响。结果表明：链状分子在差溶剂中在良溶剂中更容易吸附于固体表面；长链分子的吸附量比短链分子大；吸附层厚度主要受分子链长影响，与拖尾形构型伸展到体相中的长度相当；各类吸附构型均以短链为主和环形构型数目比拖尾形构型数目多得多。     

粒子在溶液中吸附聚电解质行为及粒子间的相互作用(Ⅰ)模型建立

以自洽场 (CSF)理论为基础 ,综合粒子、溶剂分子和聚合物链节之间的相互作用及聚合物分子链电荷的作用对粒子在溶液中吸附聚合物的影响 ,采用前末端链节决定随机行走模型 (PRDWM)建立了粒子在聚合物溶液中吸附平衡后的粒子表面的链节密度分布的数学模型———链节密度分布函数 ,并通过吸附前后粒子表面自由能的变化建立了吸附聚合物分子链的粒子间的相互作用势能模型     

含固体颗粒嵌段共聚高分子熔体微相结构的Monte Carlo模拟

采用改进的键长涨落空穴扩散算法,在立方格子上对含固体颗粒的两嵌段共聚高分子熔体的微相结构进行了Monte Carlo(MC)模拟. 重点考察了固体颗粒的大小、固体颗粒与嵌段共聚高分子的选择性作用、共聚高分子链的组成fA等因素对熔体微相结构的影响. 模拟结果表明,固体颗粒与高分子链节有选择性吸附作用时不利于形成层状相,而倾向于形成柱状或网络状结构;适当大小的惰性固体颗粒(与高分子链嵌段的长度相当)有利于系统形成层状相结构;无论系统是否含有固体颗粒,嵌段共聚高分子的对称程度增加都有利于形成层状结构.     

Competition between micellization and adsorption of diblock copolymers in a colloidal system

Significant adsorption of polystyrene-poly(ethylene oxide) (PS-PEO) diblock copolymers onto PS latex particles in an aqueous dispersion is accomplished through suppression of micelle formation by adding tetrahydrofuran (THF) as a cosolvent. We add THF, a good solvent for the micelle core, to weaken the micelle and allow free chains for adsorption to the colloidal particles. Choosing a PS colloidal particle as the adsorption substrate (thus the adsorbed PS block can fully wet the subsurface), we eliminate the complications which arise from micelle formation on the colloidal surface. Since the PS particles swell in the mixed solvent, the adsorbed PS block may penetrate into the swollen latex core, which is favored for entropic reasons. A subsequent water quench of the system to a low THF solution shrinks the PS particle to its original size while retaining most of the adsorbed polymers. The adsorbed chains cannot be removed by adding surfactants or raising temperature to 90°C, indicating that the adsorbed layer is tightly attached to the surface due to kinetic hinderance of the chains in a confined environment. Neutron scattering experiments is being carried out to settle whether the PS penetrates the PS particle. © 1995 John Wiley & Sons, Inc.     

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.     

Excluded volume effect on the self-assembly of amphiphilic AB diblock copolymer in dilute solution

The self-assembly of amphiphilic AB diblock copolymer in solution with different molecular size was investigated by using the self-consistent field theory (SCFT). By continuously varying the solvent size and the polymer concentration, the phase diagram is constructed. The aggregate concentration of the amphiphilic AB diblock copolymer decreases in solution with larger solvent size. The phase will transit in solution with different solvent size due to the excluded volume interaction effect. This widely existing excluded volume effect is very useful for the separation of polymers and helpful for understanding the crowding effect in bio-molecules.     

Adsorption at the solution-solid interface: Alkyd resin on TiO2 pigment

Gel permeation chromatography results obtained from the adsorption of alkyd from different solutions on anatase TiO₂ surfaces are reported, and the influences of the solvent–resin interactions in the adsorption process are discussed, covering the thickness of the adsorbed layer, the type of molecular weight species adsorbed, and its dependence on the concentration of the solution. Resin–pigment interaction was found to be influenced by the type of solvents used.     

Conformation and thermodynamics of adsorbed macromolecules at the liquid/solid interface

Calorimetric measurements and results of the adsorption of poly(ethylene glycols) on Aerosil out of solution are reported. With the aid of conformation models for the adsorbed macromolecules and by comparing with the results on low molecular weight model substances, the measured values and their dependence on coverage, molecular weight and solvent are discussed. The resulting structure of the polymer layer, characterized by the adsorbed amount, the number of adhesive segments, the adsorption enthalpy, the thickness and the concentration of the adsorbed layer is verified by i.r. spectroscopic and ellipsometric data.     

电解质溶液中表面活性剂控制吸附下液滴的速度

引　言Ｍａｒａｎｇｏｎｉ应力使液滴在充满表面活性剂的连续介质中运动比在洁净介质中运动慢得多 Ｄａｖｉｓ和Ａｃｒｉｖｏｓ[1]以及Ｓａｄｈａｌ和Ｊｏｈｎｓｏｎ[2 ]采用线性吸附模型从理论上研究了表面活性剂对液滴运动的影响 在假设活性剂不可溶且忽略其在液滴表面扩散的情况下 ,Ｋｉｍ[3]得到了受活性剂影响的液滴迁移速度的解析解 在考虑活性剂表面扩散的情况下 ,Ｋｉｍ[4 ]进一步研究了液滴的运动·陈晋南和Ｓｔｅｂｅ[5 ]采用非线性Ｌａｎｇｍｕｉｒ和Ｆｒｕｍｋｉｎ吸附模型 ,考虑了液滴与表面活性剂之间吸附单饱和及非理想相…     

The melt rheological behavior of AB,ABA, BAB,and (AB)n block copolymers with monodisperse aramide segments

The melt rheological behavior of segmented block copolymers with high melting diamide (A) hard segments (HS) and polyether (B) soft segments was studied. The block copolymers can be classified as B (monoblock), AB (diblock), ABA (triblock, diamide end segment), BAB (triblock, diamide mid‐segment) and ? (AB)_n? (multiblock) block copolymers. Varied were the number of HS in the chain, the HS concentration, the position of the HS (in the chain or at the end of the chain) and the molecular weight of the copolymers. The melt rheological behavior of the copolymers was studied with a plate–plate method. The materials B (monoblock), BAB (triblock, diamide mid‐segment), and ? (AB)_n? (multiblock) block copolymers had a rheological behavior of a linear polymer and the complex viscosity increased with molecular weight. Surprisingly, the diblock copolymers AB and the triblock copolymers ABA at low frequencies and near the melting temperature of the copolymers had the behavior of a gelled melt. The diamide segments at the chain end seemed to form aggregates, whereas the diamide mid‐segments did not. Also, time‐dependent rheology of diblock copolymer confirmed the network structure built up in the melt. The block copolymers with H‐bonding diamide end segments had a thixotropic behavior. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Hydrazinodeoxycellulose for collection of metal ions from aqueous solution

We measured ellipsometrically the adsorption of polystyrene and polymethylmethacrylate on high-vacuum-vapoured chromium-, platinum- and gold-mirrors from various solvents under variation of the molecular weight of polymers. For both polymers we find an increase in thickness and adsorbed amount with an increase in polymer-concentration of solution. The concentration of the adsorbed polystyrene-film decreases, the concentration of the adsorbed polymethylmethacrylate-film increase with the polymer concentration of solution. Molecules of high molecular weight produce bigger thicknesses and adsorbed amounts than molecules of low molecular weight. With increasing polarity of the adsorbent we find an increase of thickness and amount of the adsorbed layer and a decrease of concentration. An increasing polarity of the solvent results in a decrease of thickness and amount and in an increase of concentration of the adsorbed layer. In saturation the polystyrene-molecules adsorb in the conformation of statistical coils. For the polar PMMA-molecules we find a divergent behaviour of the adsorption as a result of the strong interactions between the polar polymer-segments.     

金刚烷胺/氧化石墨烯复合材料的制备及其吸附性能

以氧化石墨烯和金刚烷为原料，通过水相合成法制备了金刚烷胺功能化氧化石墨烯复合材料A/GO，以FT-IR、XRD和XPS对A/GO进行了结构表征，并考察了A/GO对有机染料的吸附性能。结果表明，与氧化石墨烯相比，A/GO对甲基蓝（AB93）表现出高效吸附性，其吸附动力学和吸附等温模型分别符合拟二级动力学和Langmuir模型，理论最大吸附容量（qm）为1250.0 mg/g。热力学分析表明，A/GO吸附AB93是自发的放热过程。A/GO吸附AB93对盐（NaCl和KCl）表现出良好的耐盐性，而CaCl2能有效地促进A/GO吸附AB93。对于刚果红和AB93等的混合染料体系，A/GO能选择性吸附AB93。