Temperature-induced three-phase equilibrium of medium-chain-length poly-3-hydroxyalkanoates-incorporated emulsion system for production of polymeric nanoparticle

The study investigated the effects of temperature on the phase behavior of medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA)-incorporated emulsion system. It is suggested that the three-phase equilibrium consisting of lamellar liquid crystalline (L_a), bi-continuous microemulsion (D), and oil-swollen micelle phases formed in the vicinity of optimal formulation when the combination of phase inversion composition (PIC) and phase inversion temperature (PIT) methods was applied. The interaction effects between two parameters, viz. temperature and mcl-PHA molecular weight, influenced the lamellar/bi-continuous microemulsion formation within the mcl-PHA-incorporated emulsion. It is suggested that the lamellar/bi-continuous microemulsion phase of mcl-PHA-incorporated emulsion can be thermally induced from multiple emulsion system proximately before EIP, and its hypothetical formation mechanism is elucidated in this study.     

Microenvironment Effect on the Location Distribution of Phenothiazine in Cetyltrimethylammonium Bromide/<Emphasis Type="Italic">n</Emphasis>-Pentanol/H<Subscript>2</Subscript>O W/O and Bi-continuous Microemulsions

In cetyltrimethylammonium/n-pentanol/H₂O W/O (W/O = water in oil microemulsion) mixtures and bi-continuous microemulsions, phenothiazine (PTZ) molecules exist in the membrane phase of the dispersion either with the N atom or with the S atom pointed toward the polar head of cetyltrimethylammonium (CTAB). Cyclic voltammetry has been used to investigate the effects of the compositions and structures of the microemulsions, pH, and the salt on the location distribution of PTZ in the membrane phase of the dispersion in CTAB/n-C₅H₁₁OH/H₂O W/O and bi-continuous microemulsions. The results show that the location distribution of PTZ in the membrane phase of the dispersion in microemulsions is mainly dependent on the hydrogen bond between PTZ and n-C₅H₁₁OH (or the counterion), and on the electrostatic attractive interaction between the N atom in PTZ and the polar head of CTAB.     

Bio-based polylactide/epoxidized natural rubber thermoplastic vulcanizates with a co-continuous phase structure

A bio-based thermoplastic vulcanizate (TPV) composed of polylactide (PLA) and epoxidized natural rubber (ENR) was fabricated through dicumyl peroxide-induced dynamic vulcanization. It was found that the crosslinked ENR phase had a specific continuous structure, hence forming a bi-continuous structure in the TPV. We designed cyclic stress-strain, stress-soften and stress-relaxation tests and SEM observation to reveal the relationship between the PLA continuous phase and crosslinked ENR continuous phase. It was found that the PLA phase generated crazes to adapt the elongation of the ENR continuous phase during stretching. At the same time, the enhanced interface between PLA and ENR kept the stress transferring between the two phases. The ENR with more epoxy groups showed better compatibility with PLA, which resulted in better mechanical properties.     

Competition of phase dissolution and crystallization in poly(ε-caprolactone)/poly(styrene-co-acrylonitrile) blend

Blend of poly(ε-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) containing 27.5 wt% of acrylonitrile was studied. The PCL/SAN blend having LCST (lower critical solution temperature) phase boundary above the melting point T_m of PCL offered an excellent opportunity to investigate the competition of liquid-solid phase transition (crystallization) and liquid-liquid phase transition (phase dissolution). A blend with the critical composition (80/20 PCL/SAN) underwent a temperature-jump above LCST to proceed spinodal decomposition, yielding a regularly phase-separated structure (SD structure). Then, it was quenched to the temperatures below T_m at which both the crystallization and the phase dissolution could occur. By transmission electron microscopy it was found that during isothermal annealing after quenching to high temperatures close to T_m (e.g. 51 °C), the SD structure gradually disappeared, and then the crystallization started from a single-phase mixture to yield normal crystalline structure similar to that of a neat crystalline polymer. At lower temperatures (e.g. 40 °C), crystallization quickly occurred and the SD structure was preserved, implying that the crystallization prevailed over the dissolution yielding a bi-continuous structure consisting of amorphous (SAN-rich) and crystalline (PCL-rich) regions. At intermediate temperatures (e.g. 45 °C), the phase dissolution competed with the crystallization, resulting in a bi-continuous structure with longer periodic distance and a broad boundary having a gradient in composition of amorphous region between PCL crystal lamellae. Light-scattering analysis quantitatively revealed a competition of the crystallization and the phase dissolution in terms of the crystallization rate (from H_v scattering) and the apparent diffusion coefficient for dissolution (from V_v scattering).     

Evaporation from an ionic liquid emulsion

The conditions during evaporation in a liquid crystal-in-ionic liquid microemulsion (LC/microEm) were estimated using the phase diagram of the system. The equations for selected tie lines were established and the coordinates calculated for the sites, at which the evaporation lines crossed the tie lines. These values combined with the coordinates for the phases connecting the tie lines were used to calculate the amounts and the composition of the fractions of the two phases present in the emulsion during the evaporation. One of the emulsion phases was a lamellar liquid crystal and high energy emulsification would lead to the liquid crystal being disrupted to form vesicles. Such a system tenders a unique opportunity to study the interaction between vesicles and normal micelles, which gradually change to inverse micelles over bi-continuous structures. The amount of vesicles in the liquid phase versus the fraction liquid crystal was calculated for two extreme cases of vesicle core size and shell thickness. The limit of evaporation while retaining the vesicle structure was calculated for emulsions of different original compositions assuming the minimum continuous liquid phase to be 50% of the emulsion.     

An Investigation of Structure Transition in Sodium Dodecyl Trioxyethylene Sulfate／n-Butanol／n-Octane／Water System by Dielectric Relaxation Spectroscopy Method

IntroductionDielectricrelaxationspectroscopy(DRS) possess esanimportantpositioninmodern physicochemicalanalysis .Dielectricmeasurementscanbedoneinsuchawidefrequencyrangeof 10 - 5— 10 11Hz ,makingitpossibletodetectallkindsofprocessesofvarioussys tems[1] .DRSisbasedonthepolarizationtheory ,in cludingdipolereorientation polarization ,interfacialpolarization ,ionicpolarizationandelectronicpolariza tion ,ofwhichinterfacialpolarizationis prevalent.Whenthereexistsaclearphaseinterface ,aninterfa c…     

Microemulsions from silicone oil with an anionic/nonionic surfactant mixture

Microemulsion phases have been prepared for the first time from the silicone oil "M(2)" (hexamethyldisiloxane) and a surfactant mixture of a nonionic surfactant "IT 3" (isotridecyltriethyleneglycolether) and an ionic surfactant Ca(DS)(2) (calciumdodecylsulfate). For such a surfactant mixture the hydrophilicity of the system can be tuned by the mixing ratio of the two components. With increasing IT 3 content, the surfactant mixtures show a L(1)-phase, a wide L(α)-region and a narrow L(3) sponge phase. For constant temperature, two single phase channels exist in the microemulsion system. The lower channel (low IT 3 content) ends in the middle of the phase diagram with equal amounts of water and oil, the upper channel begins with the L(3)-phase and passes all the way to the oil phase. Conductivity data show that the upper channel has a bi-continuous morphology up to 40% oil while the lower channel consists of oil droplets in water. In contrast to previous studies on nonionic systems, the two single phase channels are not connected and microemulsions with equal amount of oil and water do not have a bicontinuous structure.     

Morphology changes of polyvinylidene fluoride membrane under different phase separation mechanisms

In this study, the strong morphology changes of polyvinylidene fluoride (PVDF) membrane were demonstrated by changing phase separation process from a diffusion induced phase separation (DIPS) to its combination with a thermally induced phase separation (TIPS) which can be attained via changing the diluent – dibutyl phthalate (DBP) content in solvent – N,N-dimethylacetamide (DMAc). The solvent became poor when it mixed with DBP, so TIPS could occur in the quenching process which resulted in a rapid crystallization process. In this process, the porous skin and interlocked small crystallite particle (or bi-continuous) morphologies were formed, while the porous skin and leaf-like network morphology came from the rapidly crystallizing in TIPS, the large spherulite and dense skin could be attributed to the relaxed crystallization in DIPS, the finger-like macro-void and dense skin resulted from the liquid–liquid phase separation in DIPS. Simply speaking, the different membrane morphologies can be obtained by changing the DBP content in DMAc and the coagulation bath temperature.     

模板法制备介孔材料的研究进展

从微孔到中孔或介孔材料的制备过程中．离子模板、乳液模板、液晶模板及至细菌模板得到广泛的应用．具有空间规整性的介孔材料就其介观结构所具有的空间群而言，有P6mm，P6 3／mmc，Pm3n，Ia3d；就其介观结构的形态而言．有二维六方，三维六方，双连续立方，La层状相，多层囊泡等．本文对MCM系列，SBA-n系列、MSU系列，以及那些较为单一的硅基品种FMS-16、HMS等的制备体系及其特点进行了综述．对介孔分子筛合成中常用的表面活性剂分子类型进行了归纳．本文针对的是单一表面活性剂作模板的类型，对那些混合型模板则未予详细介绍．     

嵌段共聚物受限自组装的实验研究进展

嵌段共聚物有着丰富的相行为,在本体中会发生微相分离形成球形、柱形、双连续形和层状结构.当嵌段共聚物被限制在一定的空间几何中且空间几何特征尺寸与嵌段共聚物的平衡周期相近时,自组装过程会受到强烈的影响而形成与本体不同的自组装结构.本文从实验研究方面总结了限制因素和边界条件对嵌段共聚物受限自组装过程的影响,并指出了当前存在的一些问题以及今后的发展方向.     

Bi-continuous macroporous polymer derived from oligo-ethylene oxide di-vinyl ether by a cationic polymerization

We have newly developed a bi-continuous macroporous polymer derived from oligo-ethylene oxide di-vinyl ether by cationic polymerization. Although vinyl ether is not easily polymerized using radical polymerization in its homo-polymerization, we have found that a cationic polymerization with a combination of good and poor solvents for the glowing polymer chain realized bi-continuous macroporous polymer as the first example of cross-linked, macroporous vinyl ether polymer.     

Structure evolution of bio-based PLA/ENR thermoplastic vulcanizates during dynamic vulcanization processing

The thermoplastic vulcanizates (TPVs) of Polylactide (PLA)/Epoxidized natural rubber (ENR) were prepared by dynamic vulcanization technology. The processing torque, crosslink density, morphology of PLA/ENR blends, and PLA's molecular weight during the processing were investigated by HAAKE rheometer, swelling measurement, scanning electron microscopy (SEM), and gel permeation chromatography (GPC). It was found that the vulcanization of ENR completed at the turning point after torque peak. After the turning point, the torque and crosslink density decreased with the processing time increasing. Moreover, the morphology of PLA/ENR blends showed bi-continuous structure during the dynamic vulcanization processing, and the phase size of PLA/ENR was increased with processing time and temperature. GPC results showed PLA degradation mainly happened after torque turning point. Thermal gravimetric analysis (TGA) results indicated that some parts of PLA would graft on ENR during processing, and the higher the processing temperature, the more the PLA was grafted.     

Preparation of hydrophilic poly(vinylidene fluoride) membrane by in-situ grafting of N-vinyl pyrrolidone via a reactive vapor induced phase separation procedure

Increasing hydrophilicity of hydrophobic membrane is one of the strategies to improve its antifouling performance. Herein we report a procedure of reactive-vapor induced phase separation to prepare an N-vinyl pyrrolidone (NVP) modified poly(vinylidene fluoride) (PVDF) membrane to improve its hydrophilicity. PVDF solution containing NVP monomer was cast in ammonia water vapor atmosphere to prepare the modified membrane. During the process, PVDF was dehydrofluorinated by the reactive vapor of ammonia water to generate double bond of FC═CH, and then NVP was grafted. The degree of grafting modification and the microstructure evolution of the membrane were studied by adjusting the amount of NVP addition. A possible mechanism of membrane formation from crystallization gelling to non-crystallization gelling has been proposed to understand the morphology change from nodular sphere to bi-continuous microstructure with fibril matrix. It has been found that rising the degree of modification has changed the polymorph of PVDF from β to α crystalline phase, as well as turned the hydrophobic PVDF membrane into hydrophilic. Moreover, the modified membrane displayed obvious reduction in bovine serum albumin adsorption, suggesting improvement in anti-fouling performance. Therefore, our work provides an easy strategy to prepare hydrophilic PVDF membrane, which may have promising potential applications.     

Synergistic effect of solvent and solid additives on morphology optimization for high-performance organic solar cells

Science China Chemistry - Controlling the photoactive layer morphology towards nanoscale bi-continuous donor/acceptor interpenetrating networks is a key issue to build high-performance organic...     

Effect of microdomain structure on the mechanical behavior of binary blends

The relationship between microphase structure and mechanical response of the binary blends consisting of polystyrene-block-polyisoprene-block-polystyrene copolymer and low molecular weight polystyrene has been investigated. Low molecular weight polystyrene was chosen to obtain uniformly solubilized nano-blends without macrophase separation. The specimens were solution-cast by adding different amounts of homo-polystyrene to acquire different microphase structures. Small angle X-ray scattering(SAXS), transmission electron microscopy(TEM) and atom force microscopy(AFM) have been used to study the microdomain and grain structure. It is observed that the structural changes in d-spacing and grain size on account of different amounts of polystyrene alter the mechanical behavior in both monotonic tensile and cyclic tests. The elastic and the Mullins effects are strongly sensitive to the changes in d-spacing and grain sizes. Moreover, the sample with bi-continuous structure shows the largest tensile strength and Mullins effect. In addition, the Mooneye-Rivlin phenomenological model was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of these styrenic nano-blends.     

Structural transformations of metal alloys under electrocatalytic conditions

Nanostructured alloys are efficient catalysts for mediating renewable energy storage and recovery reactions. The morphology and composition of an alloy can change during catalysis; particularly for potentials more oxidizing than the reversible hydrogen electrode. The formation of noble-metal shells covering an alloy core, or bi-continuous nanoporosity, is a common way an alloy can evolve by a corrosion mediated process. Recently, it was found that alloys can reconstruct within the bulk and form an ordered intermetallic material with different crystal structures and compositions than the starting material during corrosion. This review will discuss the different pathways alloys can be altered by electrochemistry. We will discuss the mechanisms which cover known structural changes and the more recently discovered process involving electrochemically driven incongruent phase transformations. Insights into the transformation of alloy materials are important for understanding how to prepare catalysts with improved electrochemical stability, and for synthesizing materials.     

Transport properties of alternative fuel microemulsions based on sugar surfactant

Electrical conductivity of fuel microemulsion composed of diesel, pentanol, water, and sucrose laurate as surfactant was investigated over a wide range of water contents varying from 0 to 90?wt% and temperature varying from 10°C to 50°C. Conductivity measurements were performed on samples, the composition of which lie along the one-phase channel using a conductivity meter. Activation energy of conduction flow was evaluated. The hydrodynamic radius as a function of temperature in the aqueous phase-rich region (90?wt%) was measured using the dynamic light scattering (DLS) method. The microstructure of the microemulsion was further investigated by NMR diffusometry by which the self-diffusion coefficients for water were determined at 25°C. Electrical conductivity increases with water content up to 40?wt% and the percolation threshold was observed, and then stabilizes between 40 and 80?wt% then decreases. Percolation threshold temperature at constant composition was monitored as 36°C for water contents below 80?wt% and as 34°C for water contents above that. As predicted by the conductivity measurements, the determined self-diffusion coefficients of water confirmed the structural transition from discrete W/O droplets to bi-continuous phase and finally to O/W droplet microemulsion.     

Porous carbon and carbon composite hollow spheres

In this communication, we propose a template approach toward synthesis of carbon hollow spheres by direct carbonization of highly crosslinked sulfonated polystyrene gel hollow spheres (sPS). The sulfonic acid group can facilitate carbonization. Moreover, the acid group can also induce a favorable growth of other materials within the sPS gel-forming carbon-based composite shell such as bi-continuous C/SiO₂ and their derivative ceramic SiC. Release of small molecules during polymers decomposition results porous shell.     

EFFICIENT POLYMER PHOTOVOLTAIC DEVICES BASED ON POLYMER D-A BLENDS*

Recent work demonstrated that efficient solar-energy conversion could be achieved in polymer photovoltaic cells(PVCs) based on interpenetrating bi-continuous networks. In this paper we present a comprehensive study on improvingenergy conversion efficiencies of PVCs based on composite films of MEHPPV and fullerene derivatives. Carrier collectionefficiency of ca. 30% el/ph and energy conversion efficiency of 3.9% were achieved at 500 nm. At reverse bias of 15 V, thephotosensitivity reached 0.8 A/W, corresponding to a quantum efficiency over 100% el/ph. These results suggest that highefficiency photoelectric conversion can be achieved in polymer devices with M-P-M structure. These devices are promisingfor practical applications such as plastic solar cells and plastic photodetectors.     

阴离子型微乳液的电导行为及其溶液结构

根据电导测量,研究了属于W/O→双连续→O/W一类微乳液的十二烷基硫酸钠(SDS)/正丁醇/辛烷/水体系的溶液结构.并探讨了表面活性剂离子对微乳液导电行为的贡献,以及表面活性剂与助表面活性剂含量、油含量对微乳液溶液结构的影响.微乳液的导电行为在W/O子区域中主要是由于SDS阴离子和在O/W子区域中是由于Na离子的影响.在双连续区(IZ)中SDS阴离子和Na阳离子都能影响导电行为增加表面活性剂含量有助于形成O/W微乳液,而助表面活性剂和油含量都增加有助于于形成W/O微乳液.