Theoretical Calculation of Flory‐Huggins and Scattering Interaction Parameters by Means of the Lattice Fluid Theory for PVME/PSD Blends

By fitting the spinodals of poly(vinyl methyl ether)/deuterated polystyrene (PVME/PSD) systems, the adjustable parameters ε*₁₂ and δε* in the Sanchez‐Balasz lattice fluid (SBLF) theory could be determined for different molecular weights. According to these parameters, Flory‐Huggins and scattering interaction parameters were calculated for PVME/PSD with different molecular weights by means of the SBLF theory. From our calculation, Flory‐Huggins and scattering interaction parameters are both linearly dependent on the reciprocal of the temperature, and almost linearly on the concentration of PSD. Compared with the scattering interaction parameters, the Flory‐Huggins interaction parameters decreased more slowly with an increase in the concentration for all three series of blends.     

Phase separation in PS/PVME thin and thick films

Phase separation in both thin and thick films of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was studied by small-angle laser light scattering (SALLS), atomic force microscopy (AFM), optical microscopy, and X-ray photoelectron spectroscopy (XPS). Blend films with controlled thickness were obtained by spin-coating polymer-toluene solutions with various concentrations. Films with thicknesses smaller and larger than the maximum wavelength of concentration fluctuations were considered. Morphology of the blend films was characterized during and after phase separation. The obtained peculiar morphology was related to surface enrichment with the lower-surface-energy component, as was verified by XPS analyses.     

Glass-transition temperatures of PVME - PS blends: Influence of the molecular weight of PS

Glass-transition temperatures of compatible PVME/PS blends show, beside the well-known composition dependence, a predominant influence of the molecular weight of the blend components, mainly that of PS. This influence can be reproduced by an extended Gordon-Taylor equation only. The values, however, of the parameters of the extended Gordon-Taylor equation show molecular specific correlations.     

振荡剪切流场下PS/PVME/SiO2复合物的相行为

利用光学显微镜-剪切台联用系统研究了振荡剪切流场下聚苯乙烯（PS）/聚甲基乙烯基醚（PVME）/二氧化硅（SiO₂）纳米粒子复合物的热力学稳定性. 结果表明,小振幅振荡剪切可导致PS/PVME共混物出现类似在稳态流场下的剪切诱导相容及剪切诱导相分离现象. 共混体系存在临界振荡频率ω_c,当振荡频率低于ω_c时,发生剪切诱导相分离（SID）行为,反之发生剪切诱导相容（SIM）行为. SiO₂纳米粒子的加入使复合体系的相容性提高. 存在一个临界SiO₂纳米粒子含量φ_c,当SiO₂纳米粒子含量高于φ_c时,复合体系中不存在临界振荡频率ω_c,低振荡频率下的剪切诱导相分离得到抑制. 此外,复合体系的上述行为与升温速率和共混物组成密切相关.     

Theoretical estimation of thermodynamic properties of the system PS/PPO on the basis of modified combining rule of Sanchez-Lacombe lattice fluid model

The three scaling parameters described in Sanchez-Lacombe lattice fluid theory (SLLFT), T^*, P^* and ρ^* of pure polystyrene (PS), pure poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and their mixtures are obtained by fitting corresponding experimental pressure-volume-temperature data with equation-of-state of SLLFT. A modified combining rule in SLLFT used to match the volume per mer, υ^* of the PS/PPO mixtures was advanced and the enthalpy of mixing and Flory-Huggins (FH) interaction parameter were calculated using the new rule. It is found that the difference between the new rule and the old one presented by Sanchez and Lacombe is quite small in the calculation of the enthalpy of mixing and FH interaction parameter and the effect of volume-combining rule on the calculation of thermodynamic properties is much smaller than that of energy-combining rule. But the relative value of interaction parameter changes much due to the new volume-based combining rule. This effect can affect the position of phase diagram very much, which is reported elsewhere [Macromolecules 34 (2001) 6291]     

Phase Separation,Wetting and Dewetting in PS/PVME Blend Thin Films: Dependence on Film Thickness and Composition Ratio

The effects of film thickness and composition ratio on the morphology evolution of polystyrene (PS)/poly(vinyl methyl ether) (PVME) blend thin films were investigated. Diverse morphology evolutions including droplet-matrix structure, hole emergence, bicontinuous structure formation, percolation-to-droplet transition could be observed under annealing in two-phase region, depending on film thickness and composition ratio. The mechanism for these morphology variations was related to the complex effects of phase separation, dewetting and preferential wetting. The comparison between the thickness of bottom PVME layer and the twice of gyration radius 2R_g(PVME) played a dominant role in morphology control. Only when the PS/PVME film had specific film thickness and compositional symmetry, phase separation and dewetting could happen in sequence.     

修正的格子空间的密度泛函理论在狭缝中的应用

对描述单原子分子溶液在狭缝中的吸附现象的格子空间的密度泛函理论 (LDFT, lattice density functional theory)进行了修正, 在系统Helmholtz函数的推导中引入了平均场近似校正和Gibbs-Helmholtz方程. 对比Monte Carlo (MC)模拟结果, 发现LDFT理论对吸附分子在狭缝中的吸附浓度分布的预测与模拟数据有较大的偏差, 而修正模型的结果与模拟数据吻合较好 .随着体相浓度的变化,分子在狭缝中具有多级吸附行为, 具体表现为在特定体相浓度区, 对相同的体相浓度,狭缝中同时存在不同的分子浓度分布, 而在Gibbs等温线上可以明显看出多级吸附的性质. 对比修正前后的结果发现,两者均可以预测多级吸附行为, 但仍存在着较大的差异.     

Modeling Photovoltaic Performances of BTBPD-PC61BM System via Density Functional Theory Calculations

Designing and fabricating high-performance photovoltaic devices have remained a major challenge in organic solar cell technologies.In this work,the photovoltaic performances of BTBPD-PC₆₁BM system were theoretically investigated by means of density functional theory calculations coupled with the Marcus charge transfer model in order to seek novel photovoltaic systems.Moreover,the hole-transfer properties of BTBPD thin-film were also studied by an amorphous cell with 100 BTBPD molecules.Results revealed that the BTBPDPC₆₁BM system possessed a middle-sized open-circuit voltage of 0.70 V,large short-circuit current density of 16.874 mA/cm²,large fill factor of 0.846,and high power conversion efficiency of 10%.With the Marcus model,the charge-dissociation rate constant was predicted to be as fast as 3.079×10¹³ s^-1 in the BTBPD-PC₆₁BM interface,which was as 3-5 orders of magnitude large as the decay (radiative and non-radiative) rate constant (10⁸-10¹⁰ s^-1),indicating very high charge-dissociation efficiency (～100%) in the BTBPD-PC₆₁BM system.Furthermore,by the molecular dynamics simulation,the hole mobility for BTBPD thin-film was predicted to be as high as 3.970×10^-3 cm²V^-1s^-1,which can be attributed to its tight packing in solid state.     

超临界流体色谱流程设计及其应用

本文设计了多功能超临界流体色谱流程,流程中包括毛细管/微填充柱SFC,GC,计算机控制温度、压力、密度及信号采集、处理,配置有超临界流体萃取池,解决了超临界流体色谱分流口易堵问题。利用该流程,将石腊、DC-200气相色谱固定相、黄油、蜂蜡、救心油、红花油等样品进行超临界流体色谱分离。     

Phase separation dynamics of a poly(vinyl methyl ether)/polystyrene (PVME/PS) blend studied by ultrafast differential scanning calorimetry

In this work, ultrafast differential scanning calorimetry (UFDSC) is used to study the dynamics of phase separation. Taking poly(vinyl methyl ether)/polystyrene (PVME/PS) blend as the example, we firstly obtained the phase diagram that has lower critical solution temperature (LCST), together with the glass transition temperature (T_g) of the homogeneous blend with different composition. Then, the dynamics of the phase separation of the PVME/PS blend with a mass ratio of 7:3 was studied in the time range from milliseconds to hours, by the virtue of small time and spatial resolution that UFDSC offers. The time dependence of the glass transition temperature (T_g) of PVME‐rich phase, shows a distinct change when the annealing temperature (T_a) changes from below to above 385 K. This corresponds to the transition from the nucleation and growth (NG) mechanism to the spinodal decomposition (SD) mechanism, as was verified by morphological and rheometric investigations. For the SD mechanism, the temperature‐dependent composition evolution in PVME‐rich domain was found to follow the Williams–Landel–Ferry (WLF) laws. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1357–1364     

Molybdenum Disulphide Precipitation in Jet Reactors: Introduction of Kinetics Model for Computational Fluid Dynamics Calculations

In our previous work, we used the population balance method to develop a molybdenum disulphide kinetics model consisting of a set of differential equations and constants formulated to express the kinetics of complex chemical reactions leading to molybdenum disulphide precipitation. The purpose of the study is to improved the model to describe the occurring phenomena more thoroughly and have introduced computational fluid dynamics (CFD) modelling to conduct calculations for various reactor geometries. CFD simulations supplemented with our nucleation and growth kinetics model can predict the impact of mixing conditions on particle size with good accuracy. This introduces another engineering tool for designing efficient chemical reactors.     

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C₄ mim][X]) salts. The rotational isomerism of the [C₄ mim]⁺ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the “localized structure features” that apparently exist in ionic liquids are described. It is hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed.     

Phase Diagram for a System of Polydisperse Components Consisting of the Precursor of an Epoxy/Diamine Thermoset and a Thermoplastic: Analysis Based on a Lattice Theory Model

Summary: The miscibility of a thermoplastic modifier with the precursors of an epoxy/diamine thermoset without chemical reaction was studied thermodynamically. The experimental cloud point curve showed a UCST behavior. A model based on the Flory‐Huggins lattice theory and on the Koningsveld approach was used for the thermodynamic analysis, in which the polydispersity of components was taken into account and the interaction parameter was considered depending on the temperature and composition. A phase diagram for the unreacted system was obtained. Calculations of species distributions in both separated phases were realized for different compositions of the modifier. Finally, the miscibility of our system was compared with that of the same system without diamine, obtaining a greater miscibility in the system with diamine.

Phase diagram for the system formed by the precursors of an epoxy thermoset without chemical reaction modified with different amounts of polystyrene.     

链状分子状态方程的推导及热容的推算

在Barker Henderson, Zhang以及Wertheim 等微扰理论的基础上,以方阱势硬球流体为参考体系,将Zhang的解析表达方法与Wertheim 的链成键自由能的处理方法结合起来,推导出自由链接的链状分子流体的Helmholtz自由能的解析表达式,并得到了压缩因子、内能、恒容热容等热力学性质的计算式.计算结果与MC(Monte Carlo)模拟结果吻合良好.对Zhang的解析表达式与“TPT D”(二阶Wertheim微扰理论)的结合也作了推导和计算.     

A New Curing Kinetic Model and Its Application to BPSER/DDM Epoxy System

A new model has been deduced by assumed autocatalytic reactions. It includes two rate constants, k ₁ and k ₂, two reaction orders, m and n, and the initial concentration of [OH]. The model proposed has been applied to the curing reaction of a system of bisphenol-S epoxy resin (BPSER), with4,4'-diaminodiphenylmethane (DDM) as a curing agent. The curing reactions were studied by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the curing reaction. The new model was found to fit to the experimental data exactly. Rate constants, k ₁ and k ₂ were observed to be greater when curing temperature increased. The activation energies for k ₁ and k ₂ were 95.28 and 39.69 kJ mol^–1, respectively. Diffusion control was incorporated to describe the cure in the latter stages. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Thermodynamic Model for Square-well Chain Fluid: Theory and Monte Carlo Simulation

A thermodynamic model for the freely jointed square-well chain fluids was developed based on the thermodynamic perturbation theory of Barker-Henderson, Zhang and Wertheim. In this derivation Zhang's expressions for square-well monomers improved from Barker-Henderson compressibility approximation were adopted as the reference fluid, and Wertheim's polymerization method was used to obtain the free energy term due to the bond connectivity. An analytic expression for the Helmholtz free energy of the square-well chain fluids was obtained. The expression without adjustable parameters leads to the thermodynamic consistent predictions of the compressibility factors, residual internal energy and constant-volume heat capacity for dimer, 4-mer, 8-mer and 16-mer square-well fluids. The results are in good agreement with the Monte Carlo simulation. To obtain the MC data of residual internal energy and the constant-volume heat capacity needed, NVT MC simulations were performed for these square-well chain fluids.     

点阵模型重整化在Aa-Bb缩聚反应中的应用

在渗流理论中,P.J.Reynolds等提出了求相关长度临界指数的晶格点阵重整化群的方法,它对一,二维渗流问题的计算被认为是严格的.本文试图将这种方法用到A_a-B_b缩聚反应的凝胶化问题上,得到和渗流结果相同的临界指数,而凝胶点接近高分子统计的结果。     

Vibrational Spectra and Density Functional Theory Calculations of Metallotriphenylcorroles

The infrared absorption and Raman scattering spectra were measured for the metallotriph-enylcorroles (MTPCs, M=Cu, Co, Ni, Mn). The ground-state structures and vibrational spectra of MTPCs have been calculated with the density functional theory. The observedRaman and IR bands have been assigned based on the calculation results. Due to the symmetry lowering, the vibrational spectra of MTPCs are much more complex than metal-loporphyrins, and several skeletal modes are found strongly coupled to the phenyl vibrations.The relationship between the Raman/IR frequencies and the structures of TPC ring is in-vestigated. It is found that the vibrations involving the C^I_αC^I_α stretch and C_αC_mstretch are sensitive to the size of corrole core. In particular, the frequency of υ₅, which is assigned to C^I_αC^I_α stretch in coupling with the C_αC_m symmetric stretch, increases linearly with the decrease of the corrole core-sizes and may be used as a mark band to evaluate the structural change of the metallocorroles.     

Fluorescence Behavior of Anthracene in Composite System of PBA/PS

The fluorescence emission behavior of anthracene (An) wrapt in the film cast from poly (butyl acrylate)/polystyrene composite emulsion prepared by seed emulsion polymerization was determined. The result shows that the emission spectra are sensitive to the environment of the probe An. The volatilization of solvent under film-forming will enhance the luminous emission.The heat treatment to film will weaken the fluorescence and shift the signals towards higher frequency.     

Theoretical Prediction on Photovoltaic Properties of 4Cl‐BPPQ/PC61BM System via Density Functional Theory Calculations

Designing and synthesizing high‐performable electron donor materials are very important for fabricating organic solar cell devices with high power conversion efficiency (PCE). In this work, quantum chemical and molecular dynamics calculations coupled with the Marcus‐Hush charge transfer model were used to investigate the photovoltaic properties of 4Cl‐BPPQ/PC₆₁BM. Results reveal that 4Cl‐BPPQ/PC₆₁BM system theoretically possesses a large open‐circuit voltage (1.29 V), high fill factor (0.90), and over 9% PCE. Moreover, calculations also reveal that the 4Cl‐BPPQ/PC₆₁BM system has a middle‐sized exciton binding energy (0.492 eV), but relatively small charge‐dissociation and charge‐recombination reorganization energies (0.345 eV and 0.355 eV). Based on the 4Cl‐BPPQ/PC₆₁BM complex, the charge‐dissociation rate constant, k_dis, is estimated to be as large as 6.575×10¹² s^?1, while the charge‐recombination one, k_rec, is very small (<1.0 s^?1) under the same condition due to the very small driving force (ΔG_rec=?1.900 eV). In addition, by means of an amorphous cell containing one hundred 4Cl‐BPPQ molecules, the hole carrier mobility of 4Cl‐BPPQ solid is estimated as high as 3.191×10^?3 cm²·V^?1·s^?1. In brief, our calculation shows that 4Cl‐BPPQ/PC₆₁BM system is a very promising organic solar cell system, and is worth of making further device research by experiments.