Advances in reactive polymeric surfactants for interface modification

Continued development of up-to-date polymer composite materials demands the design of certain interfacial layers in composite structure. The aim of this paper was to review recent advances in the synthesis of reactive polymeric surfactants (RPSs) and the application of 14 different RPSs for the modification of the interface in aqueous dispersions of polymers, reinforced polymer-based composites, and polymer blends. The activation (peroxidation) of planar polymer surfaces with RPSs for their further modification in order to impart specific surface properties was discussed as well. In the paper method of compatibilization of the blends of thermodynamically immiscible polymers through the formation in situ of a universal compatibilizer based on RPS was introduced. Finally, the features of the RPS macromolecules' adsorption on the surface of latex particles, inorganic filler particles, and planar polymer surfaces along with the formation of adsorbed reactive polymer layers are discussed.     

Ionic liquids as reactive additives for the preparation and modification of epoxy networks

In this study, epoxy‐networked polymeric materials containing tributyl (ethyl) phosphonium diethyl phosphate (CYPHOS^®IL169) and trihexyl (tetradecyl) phosphonium bis 2,4,4‐(trimethyl pentyl)‐phosphinate (CYPHOS^®IL104) were developed from a mixture of epoxy prepolymer (DGEBA) and different amounts of ionic liquids (10–20–30 phr). Then, the effect of the chemical nature of ionic liquids on the final properties of epoxy networks was studied. Thus, the use of phosphonium salts as new additives led to the network with a high conversion of epoxy group (>90%), a high glass transition temperature T_g (>90 °C), adjustable in function of the counteranion and an increase of the storage modulus. In addition, the hydrophobic behavior and the thermal stability of the materials were also investigated by sessile drop method and thermogravimetric analyses. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3463–3471     

Role of the interface in multicomponent materials

Studies of the relationship between interfacial structure and mechanical properties in multicomponent materials are reviewed in this article. The following categories are considered for role of the interface in multicomponent systems: Interpenetrating polymer network(IPN), catalytic effect of silane coupling agent, morphological differences of filler surface, particle-particle interaction and particle size of the filler. The interfacial role in terms of the reinforcement mechanism of the composite and the behavior in the melt state is also discussed in the multicomponent system.     

The role of lubricants in reactive compatibilization of polyolefin blends

Reactive compatibilization using liquid polybutadienes and dialkyl peroxides was studied in model low‐density polyethylene/polystyrene (4/1) blends and the commingled waste of composition similar to these blends. The influence of three types of lubricants (Ca stearate, stearic acid ‐ Loxiol G20 and paraffin ‐ Loxiol G22) on the structure and toughness of these blends was determined. In spite of the fact that in the waste material, a coarse morphology and poor toughness were found in comparison with the blend of virgin polyolefins, reactive compatibilization has approximately the same effect in both types of the blends as far as the structure parameters and mechanical behaviour are concerned. This effect is enhanced by addition of lubricants, the most efficient being the paraffin in the model blends, probably due to its partial miscibility with LDPE. In the commingled waste, liquid polybutadienes supported on precipitated SiO₂ appear to be quite efficient. No influence of the reactive compatibilization on both the crystal modification and the crystalline content was observed in both types of these blends.     

Simplified phase equilibrium equations for multicomponent systems

A simplified calculation procedure for the determination of phase equilibria for multicomponent mixtures, described by a two-parameter equation of state with mixing rules of the commonly encountered kind, is presented. A reduced set of equations, involving a finite (small) number of unknowns, is derived, under the only extra assumption that it is possible to divide molecular species into groups within which binary interaction coefficients vanish and between which these are constant. The latter condition can be relaxed, however, such that also nonconstant interaction coefficients can be taken into account without too much increase in complexity and number of equations. This covers most practical applications. The considerable simplification achieved renders the procedure especially attrarctive in cases where phase equilibrium calculations have to be performed many times.     

New reactive polymeric systems for use as waveguide materials in integrated optics

Cross-linked polymeric materials are used in a wide range of applications. Special compositions are used in micro-system technologies and its utilization is extending to integrated optics. We have been working for several years in the field of polymers for optical applications. Highly fluorinated polycyanurate systems have been proven as promising waveguide materials in integrated optics. The refractive index can be adjusted reproducibly in a wide range almost continuously. The layer quality was optimized. Low optical losses of less than 0.3 dB/cm@1550nm were obtained and working optical prototypes were developed. The birefringence had been a major problem, but this was solved by adjusting the coefficient of thermal expansion of substrate and film. We will report in this paper on the polycyanurate ester resins and the new triazine containing polymeric systems.     

Recent progress in interface modification for dye-sensitized solar cells

Interface modification on the TiO₂/dye/electrolyte interface of dye-sensitized solar cells (DSCs) is one of the most effective approaches to suppress the charge recombination, improve electron injection and transportation, and thus ameliorate the conversion efficiency and stability of DSCs. Conventional research focusing on the photoanodes interface modification before sensitization in dye-sensitized solar cells has been carried out and reviewed. However, recent studies showed that post-modification after sensitization of the TiO₂ electrode also plays a significant role on the TiO₂/dye/electrolyte interface. This post-modification using the immersing method could deprotonate dye molecules, prohibit the dye aggregation and retard the recombination reaction. As a result, it has great influence on the devices’ photovoltaic performance. This interface modification could also provide an approach to broaden the response of the solar spectrum by introducing an alternative assembling structure. An in-situ meaning of using a co-adsorbent is employed to modify the interface in the DSCs, which could retard the aggregation of the dye molecules and enhance the conversion efficiency. In addition, electrolyte additives can be used to modify the TiO₂/dye/electrolyte interface through some unique mechanisms. Based on the background of interface modification of photoanodes before sensitization, this review introduces various interface modifications after sensitization of dye-sensitized solar cells and their mechanisms.     

Interpretation of flow data for multicomponent polymeric systems

A model based on the altered free volume state concept has been proposed here to predict the melt flow index values of multicomponent systems as a function of the amount of the dispersed phase. The predictions of the model have been compared with experimental results reported in the literature on a diverse range of multicomponent polymeric systems. The agreement between the model predictions and the experimentally determined values is good.     

A comparative study of particle swarm optimization and its variants for phase stability and equilibrium calculations in multicomponent reactive and non-reactive systems

Particle swarm optimization is a novel evolutionary stochastic global optimization method that has gained popularity in the chemical engineering community. This optimization strategy has been successfully used for several applications including thermodynamic calculations. To the best of our knowledge, the performance of PSO in phase stability and equilibrium calculations for both multicomponent reactive and non-reactive mixtures has not yet been reported. This study introduces the application of particle swarm optimization and several of its variants for solving phase stability and equilibrium problems in multicomponent systems with or without chemical equilibrium. The reliability and efficiency of a number of particle swarm optimization algorithms are tested and compared using multicomponent systems with vapor–liquid and liquid–liquid equilibrium. Our results indicate that the classical particle swarm optimization with constant cognitive and social parameters is a reliable method and offers the best performance for global minimization of the tangent plane distance function and the Gibbs energy function in both reactive and non-reactive systems.     

Surface modification strategies for multicomponent polymer systems,Part I: Use of diblock copolymers as surface modifiers of rutile

Various functional diblock copolymers have been used as surface modifiers for rutile pigment in an effort to condition the solid for eventual use in multicomponent polymer systems. Coated surfaces were analyzed by inverse gas chromatography at infinite and finite dilution of the vapor phase, and by XPS. At high coverages (about 10% by weight of the pigment), the diblocks were randomly oriented at the air interface, effectively masking the surface of the rutile. At low diblock concentrations acid/base interactions dominated the orientation of the adsorbed molecule at the rutile interface, thereby also affecting the orientational states at the air interface. In this condition, the performance of the pigment in specified host polymer systems may be expected to vary with the selection of the diblock copolymer modifier. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1793–1805, 1997     

Degree of molecular self-sorting in multicomponent systems

Self-sorting represents the spontaneous and high fidelity self and/or non-self-recognition of two or more related components within a complex mixture. While the effective management of self-sorting principles perceptibly requires some key expertise in molecular programming, at a higher stage of operation it is of supreme interest to guide the process to increasingly higher degrees of self-sorting. In this article, we present the emerging principles of how to guide several components toward formation of self-sorted multicomponent architectures. To provide further guidance in denominating such systems, we suggest to utilise a systematic classification as well as a formula to evaluate their degree of self-sorting (M).     

Computer models for electrical conductivity of multicomponent solid-state systems

Models for the computer simulation of electrical conductivity of polycrystalline materials and mixtures are proposed. The effect of model parameters on the concentration behavior of conductivity is considered. The correspondence between the model parameters and the characteristics of physical objects is established, thus making it possible to analyze the spatial relations in solid-state systems.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1868–1873, November, 1993.     

A model for the examination of phase behaviour in multicomponent systems

The Percus—Yevick equation for a multicomponent system of adhesive spheres is solved exactly. For an m-component system, the phase behaviour is determined by the number and nature of zeros of a system of $\text{m}\text{(}\text{m}\text{+ 1)}\text{2}$ quadratic equations.     

Application of interface distribution functions to the evaluation of the small angle x-ray scattering of multicomponent polymer systems

A method for correcting the small angle x-ray intensity of multi-component polymer systems to compute the interface distribution function is presented. The resolution of this function can be improved to a great extent by evaluating the interference function from the measured intensity corrected for fluctuation scattering by use of a function which is proportional to the gas scattering of the investigated system. The method is applied successfully to polymer blends composed of components having similar morphology.Presented at the Spring Meeting of the Deutsche Physikalische Gesellschaft, Hamburg, March 14–16, 1988.     

IR spectral determination of mica in multicomponent systems

A procedure for the determination of mica (muscovite) in ores and concentrates by IR spectrometry is developed. It is shown that the change in the absorbance of the muscovite OH group band at 3620 cm^?1 allows a calibration plot to be constructed for the determination of 1–90% muscovite.     

Surface modification of polyolefin separators for lithium ion batteries to reduce thermal shrinkage without thickness increase

Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is important for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150 C for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.