Size Distribution and Anisotropy of the MinorPhase Droplets in Polypropylene/Ethylene-OcteneCopolymer Blends: Effects of Shear andComponent Miscibility简

In this work, polypropylene （PP）/octene-ethylene copolymer （POE） blends were injection-molded using the so- called dynamic packing injection technique, which imposed oscillatory shear on the gradually cooling melt during the packing solidification stage. In this way, the effect of shear on the size distribution and anisotropy of the minor phase droplets could be investigated. Besides, by using two kinds of POE with different octene contents, the effect of component miscibility was also studied. The results show that the droplet size is mainly determined by composition and miscibility, and droplet anisotropy is mainly determined by droplet size and shear. Most importantly, under the same processing condition, droplet anisotropy increases with droplet size, and there seems a linear fit between them, disregarding the miscibility factor. These results may provide guidance for preparing polymer blends with desired properties by tailoring their phase morphologies.     

Synthesis and Characterization of Sulfonated Polyphosphazene-graft-Polystyrene Copolymersfor Proton Exchange Membranes简

A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） copolymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.     

Morphology and Phase Composition ofGelatin-Starch Blends简

Morphology and phase compositions of different starch-gelatin blends were investigated by various microscopes: optical, SEM and synchrotron FTIR microscopy. A high amylose(80%) corn starch, grafted with hydroxypropyl to enhance flexibilty and hydrophilicity, and plasticized by poly(ethylene glycol)(PEG), was used in this work. SEM revealed that the surface became smoother after adding PEG. Optical microscopy observation revealed that compatibility between gelatin and starch was improved by adding PEG. An FTIR beam focused on a 5 μm× 5 μm detection area by the micro-spectroscope was used to map chemical composition. The ratio of areas of the saccharide bands(1180–953 cm 1) and the amide I and II bands(1750–1483 cm 1) was used to monitor the relative distributions of the two components in the blends. The FTIR maps indicated that gelatin constituted the continuous phase up to 80% of starch content. All of the FTIR spectra showed contributions from both starch and gelatin absorptions, therefore indicating that complete demixing with pure starch and gelatin domains did not occur. The PEG improved the compatibility of the gelatin-starch blends.     

Synthesis and characterization of novel ternary deep eutectic solvents简

A series of room-temperature ternary deep eutectic solvents(TDESs) were prepared from imidazolium halides, zinc halides and amides. The [BMIM]Cl–ZnCl2 –acetamide(1:1:1) system shows the lowest freezing point( 60 8C) and lowest density in the series. The viscosity and conductivity of TDESs have an exponential relationship with temperature and can be fitted by Arrhenius equation.     

Preparation and Characterization of Polyborosiloxanesand Their Blends with Phenolic Resin as ShapeableCeramic Precursors简

Two polyborosiloxanes(PBSis) with char yield up to 74.13% at 800 °C were synthesized by the direct polycondensation of boric acid with phenyltrimethoxysilane in diglyme. The PBSis were characterized by gel permeation chromatography, IR spectroscopy as well as1H-,29Si- and11B-NMR. PBSi modified phenol-formaldehyde resins(PBSi/PFs) were prepared at different PBSi/PF mass ratios and were cured at 150 °C. The PBSi/PFs were characterized by IR spectroscopy, scanning electron microscopy, thermogravimetric analysis and tensile test. The results revealed that the cured PBSi/PFs had sea-island morphology and higher char yield than the common PF. PBSi/PF blend with PBSi/PF mass ratio of 0.4:1 had char yield up to 70.83% at 800 °C. The PBSi/PFs had tensile strength similar to PF. The ceramization of PBSi/PFs was also studied. The silicon boron oxycarbide(SiBOC) ceramics formed were characterized by IR spectroscopy and elemental analysis. This method provided a valuable way to prepare easily shapeable polymer blends as ceramic precursors.     

Novel Conductive PANI/Hydrophilic Thiacalix[4]areneNanocomposites: Synthesis,Characterization andInvestigation of Properties简

Nanocomposites of polyaniline(PANI) and the macrocycle thiacalix[4]arene tetra sulfonate(TCAS) were successfully synthesized in feed ratios of 1:0.25, 1:0.50 and 1:0.75 by three prevail synthetic methods, i.e. in situ polymerization, emulsion polymerization and solution casting technique. The structures of the nanocomposites were confirmed by FTIR, UV-Vis, XRD, SEM, and TEM techniques. The conductivity was measured by a four probe method. The conductivity was recorded to be as high as 105 × 10 2S cm 1for the nanocomposite with a nanometer size structure and homogeneously distributed morphology. The electroactivity of the nanocomposites was approved by cyclic voltammetry(CV) and impedance spectroscopy technique(EIS). The antioxidant ability and thermal property of the composites were further studied. Preliminary studies have evidenced the production of conductive nanocomposites with good thermal property and relatively good solubility in N-methyl 2-pyrrolidone(NMP), with the antioxidant activity reaching up to 80%.     

Synthesis and acaricidal activity of strobilurin-pyrimidine derivatives简

Pyriminostrobin, a new acaricide, was discovered in our previous studies. Because introducing fluorine into organic compounds can increase bioactivity, pyriminostrobin was modified as a series of strobilurin-pyrimidine derivatives for biological screening. The compounds were characterized by 1H NMR, MS and elemental analysis. Preliminary bioassays demonstrated that compounds 7e and 7i exhibited significant control against Tetranychus cinnabarinus （Boisd.） at 0.625 mg L^-1, and their acaricidal potencies were higher than pyriminostrobin in a greenhouse. The relationship between structure and acaricidal activity was also studied.     

Synthesis and characterization of acetylated sept-D-glucopyranose carbamate as an oligosaccharide donor简

An oligosaccharide donor, acetylated sept-o-glucopyranose tetradecyl carbamate, was designed and synthesized. This compound could be easily linked to hydroxyl-containing compounds through an Oglycosidic bond. Characterization of all the oligosaccharide intermediates and the final product was thoroughly discussed.     

环形嵌段共聚物的胶束化行为模拟简

利用Monte Carlo模拟,对比了相同组成下环形二嵌段共聚物AB和线形三嵌段共聚物ABA在选择性溶剂中的胶束化行为. 结果发现,相同链组成的环形和线形嵌段共聚物的临界胶束浓度(cmc)的差别与A嵌段的比例(fA)及B嵌段间的吸引强度(ε)密切相关. 在fA较小、ε较大的情况下,相应环形嵌段共聚物的cmc值更小;而在fA较大、ε较小的情况下,线形嵌段共聚物的cmc值更小. 为了进一步理解胶束化行为同fA及ε的关系,计算了胶束化过程中熵和势能部分对自由能的贡献. 结果表明,在所研究的fA和ε范围内,环形嵌段共聚物形成胶束时的熵损失更小,因而从熵贡献角度来看,环形嵌段共聚物更易发生胶束化. 而从势能贡献角度来看,当fA较小、ε较大时,环形嵌段共聚物形成胶束时势能有较大程度的降低,对自由能的贡献更大,因而此时环形嵌段共聚物更易发生胶束化. 而当fA较大、ε较小时,线形嵌段共聚物形成胶束时势能有较大程度的降低,对自由能的贡献更大,因而此时线形嵌段共聚物更易发生胶束化. 由此可见,对体系的胶束化自由能进行系统分析,有助于更好地理解环形和线形嵌段共聚物的胶束化行为.     

Effect of Molecular Structure on the GasPermeability of Cellulose Aliphatate Esters简

In this work, four kinds of cellulose aliphatate esters, cellulose acetate （CA）, cellulose propionate （CP）, cellulose butyrate （CB） and cellulose acetate butyrate （CAB） are synthesized by the homogeneous acylation reactions in cellulose/AmimC1 solutions. These cellulose aliphatate esters are used to prepare gas separation membranes and the effects of molecular structure, such as substituent type, degree of substitution （DS） and distribution of substituents, on the gas permeability are studied. For CAs, as the DS increases, their gas permeabilities for all five gases （02, N2, CH4, CO and CO2） increase, and the ideal permselectivity significantly increases first and then slightly decreases. At similar DS value, the homogenously synthesized CA （distribution order of acetate substituent： C6 〉 C3 〉 C2） is superior to the heterogeneously synthesized CA （distribution order of acetate substituent： C3 〉 C2 〉 C6） in gas separation. With the increase of chain length of aliphatate substituents from acetate to propionate, and to butyrate, the gas permeability of cellulose aliphatate esters gradually increases. The cellulose mixed ester CAB with short acetate groups and relatively long butyrate groups exhibits higher gas permeability or better permselectivity than individual CA or CB via the alteration of the DS of two substituents.     

Versatility of hydrophilic and antifouling PVDF ultrafiltration membranes tailored with polyhexanide coated copper oxide nanoparticles

Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm⁻²h⁻¹ and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability.     

Preparation and characterization of microporous PVDF/PMMA composite membranes by phase inversion in water/DMSO solutions

PMMA/PVDF composite membranes were prepared by isothermal immersion-precipitation of dope solutions consisting of PMMA, PVDF, and DMSO into both harsh and soft nonsolvent baths. The effects of PMMA and DMSO contents on the membrane morphology, crystal structure, thermal behavior and tensile strength of the formed membrane were investigated. For a PMMA-free casting dope immersed in a harsh bath, such as pure water, the formed membrane exhibited a typical asymmetric morphology characterized by skin, finger-like macrovoids, and cellular pores. In contrast, when a soft 70% DMSO bath was adopted, PVDF crystallized to form a membrane packed by spherulitic globules. Incorporation of PMMA gave rise to interesting morphological features; e.g., PVDF globules were observed to adhere to the interlocked polymer branches coexisting with the continuous porous channels, as revealed by high resolution FESEM imaging. XPS analysis of the surfaces of the composite membranes suggested the occurrence of a surface segregation phenomenon, wherein PVDF preferentially migrated to the top surface region of the membrane such as to minimize the interfacial energy. XRD analyses indicated that PVDF crystallized into ‘α’ structure in both PVDF and PMMA/PVDF composite membranes. The crystallinity of the membranes was found to decrease with increasing PMMA content, which was confirmed by DSC thermal analyses. The latter results also indicated a significant decrease in membrane’s melting temperature as the PMMA content was increased. Tensile strengths of the membranes were improved by inclusion of PMMA in either harsh or soft baths. However, elongation at break showed a reversed trend.     

Formation of porous poly(vinylidene fluoride) membranes with symmetric or asymmetric morphology by immersion precipitation in the water/TEP/PVDF system

The phase equilibrium boundaries of the membrane forming system, water/triethyl phosphate (TEP)/PVDF, at 25 °C were determined experimentally using cloud-point and equilibrium absorption methods. Based on the phase diagram, appropriate dope and bath compositions were selected to prepare microporous membranes by means of the isothermal immersion-precipitation technique. As a metastable casting dope with respect to crystallization was adopted, the formed membranes exhibited a uniform cross-section composed of interlocked crystal elements coexisting with the network of continuous pores, as was revealed by high resolution FESEM imaging. Morphologies of the membranes’ top surfaces were found to depend heavily on the bath strength, which was controlled by the TEP content. By changing the bath gradually from pure water to 70% TEP, the top surface evolved from a dense skin (asymmetric membrane) to a totally porous morphology (symmetric membrane). Wide angle X-ray diffraction analysis indicated that PVDF crystallized into α-type structure for all of the synthesized membranes. The crystallinity as determined from diffraction peak deconvolution was ≈65%, which value was confirmed by Differential Scanning Calorimetry (DSC). The obtained thermograms also showed a similar melting peak temperature (T_m ≈ 169 °C) for all membranes. Furthermore, water fluxes and tensile strengths of the membranes were measured. The results were found to correlate with the morphologies of the membranes.     

Crystallization behavior and electroactive properties of PVDF,P(VDF-TrFE) and their blend films

PVDF, poly(vinylidene fluoride), as a semi-crystalline polymer, has interesting electroactive properties but usual melt and solution processing techniques result in its thermodynamically favored non-polar α-phase. By comparison, poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE), PT for short, directly crystallizes in the polar β-phase under the same conditions as PVDF. In this study, blend thin films comprising PVDF and P(VDF-TrFE) were prepared by solvent casting method. The difference in the crystallization behavior is comprehensively investigated between the polymers: PVDF, P(VDF-TrFE), and the resulting blend films. It is found that replacement of the fluoride atom in TrFE monomer induces a strong steric hindrance that may alter the crystallization process to become more favorable for nucleation of the PVDF β-phase. To figure out the effect of TrFE content on the crystallization behavior and electroactive properties, films with different blend ratios of PVDF and P(VDF-TrFE) were prepared. We found that the PVDF films exhibit higher crystallization activation energy (ΔE) as PT content increases. The atomic force microscopy (AFM) in the piezoresponse force microscopy (PFM) mode illustrated that P5T5 films with equal contents of PVDF and P(VDF-TrFE) induced the highest d₃₃ values.     

Modification of porous poly(vinylidene fluoride) membrane using amphiphilic polymers with different structures in phase inversion process

Three kinds of amphiphilic polymers, including the tri-block copolymer of (polyethylene oxide)–(polypropylene oxide)–(polyethylene oxide) (I, EPTBP), the comb-like copolymer of polysiloxane with polyethylene oxide and polypropylene oxide side chains (II, ACPS) and the hyperbranched star copolymer of polyester-g-methoxyl polyethylene glycol (III, HPE-g-MPEG), were blended with PVDF to fabricate porous membranes via a phase inversion process, respectively, and the effects of the different structures of the amphiphilic polymers on the properties of the blend membranes were compared. The membranes were characterized by scanning electron microscopy (SEM), elemental analysis, X-ray photoelectron spectroscopy (XPS) analysis, mercury porosimetry, water contact angle measurements, etc. The anti-fouling properties of the prepared membranes were evaluated by static and dynamic bovine serum albumin (BSA) adsorptions. Specially, the stabilities of these amphiphilic polymers in the final membranes were estimated by continuous leaching tests. At the same time, the properties of the membranes using the amphiphilic polymers as modifiers were compared with those of the membrane using poly(ethylene glycol) (PEG) as modifier.     

动态流变学对PVDF/PTW共混物流体相容性研究

采用熔融共混法制备了聚偏氟乙烯/乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯共聚物(PVDF/PTW)共混物,利用流变仪考察了PVDF/PTW共混物的相互作用及两者的相容性.观察共混物在200℃下的流变曲线,发现在低频区,共混物中PTW含量越大,共混物的流变曲线越偏离经典流变理论,这个结果与cole-cole图相一致.通过时温叠加原理(时温等效主曲线、Han曲线和v GP曲线)系统研究了不同组成的PVDF/PTW共混体系在均相区和相分离区的黏弹行为.结果表明,在均相区,不同温度下,共混体系的动态模量利用时温叠加原理,通过水平位移就可以很好地叠加在一起,无论是储能模量还是损耗模量,在低频末端均近似地符合经典低频末端标度关系;在相分离区,动态模量偏离了经典的低频末端标度关系,其中储能模量的偏离尤为明显,从而导致了时温叠加原理的失效,相应的Han图、v GP图也表现出不同于均相体系的特征,这些特征的响应可以用来表征共混体系的相容性,表明在研究的一系列配比(PVDF/PTW 100/0、90/10、70/30、50/50、30/70、10/90、0/100,W/W)中,当PVDF/PTW=90/10(W/W)时,两者的相容性较好.SEM也证实了这个结论.     

Porous membranes modified by hyperbranched polymers: I. Preparation and characterization of PVDF membrane using hyperbranched polyglycerol as additive

Porous membranes were prepared via phase inversion process from casting solution composed of poly(vinylidene fluoride) (PVDF), N,N-dimethylacetamide (DMAc), and hyperbranched polyglycerol (HPG). The membranes were characterized in terms of surface and bulk chemical compositions, morphology, water contact angle, porosity, and water flux. The effects of HPG content on membrane structures and properties were investigated. The effect of HPG addition on the hydrophilicity was discussed as well when the compositions of coagulation bath were changed. To better understand the special effects of HPG on the structures and properties of the membranes, PVDF membranes prepared using HPG as the additive were compared with those prepared using polyethylene glycol (PEG) as the additive.     

Crystallization behavior and hydrophilicity of poly (vinylidene fluoride) (PVDF)/poly (styrene-<Emphasis Type="Italic">co</Emphasis>-acrylonitrile) (SAN) blends

Poly (styrene-co-acrylonitrile) (SAN) is a hydrophilic non-crystalline copolymer, which is initially used in this paper to improve the hydrophilicity of poly (vinylidene fluoride) (PVDF). Investigation of the crystallization behavior of PVDF/SAN blends showed that the samples presented only α phase regardless of SAN content as cooling from the melt. A double-melting phenomenon was related to the perfection or crystal size of PVDF crystals. As the SAN content is increasing, crystallization of PVDF was limited, leading to a decreased crystallinity and lamellar growth. Besides, the hydrophilicity of PVDF was improved by blending with SAN. The sample containing 70 wt.% SAN performed a similar surface property of the neat SAN owing to the besieging of the PVDF phase by SAN. Observed from the cross section of the blends, PVDF/SAN blends were partially miscible with less than 50 wt.% SAN addition. As the SAN content was more than 50 wt.%, the crystalline PVDF particles clearly dispersed in the amorphous matrix.     

Surface characteristics and hemocompatibility of PAN/PVDF blend membranes

Polyacrylonitrile (PAN) was blended with polyvinylidine fluoride (PVDF) at various ratios and made into membranes. The hemocompatibility of the resulting membranes was evaluated based on human plasma proteins adsorption, platelet adhesion, thrombus formation, and blood coagulation time. The PAN/PVDF blends exhibited partial miscibility according to the inward shifting of their two glass transition temperatures. The microstructures of blend membranes examined using atomic force microscopy (AFM) indicated that the roughness increased with the PVDF content, and the phase separation was too severe to form a membrane when the PVDF content was more than 30%. The water contact angle of PAN/PVDF blend membranes increased with the PVDF content. By blending with 20 wt% apolar PVDF the adsorption of blood proteins could be reduced, and hence the platelet adhesion and thrombus formation was also reduced. However, when the PVDF content was 30 wt%, severe thrombogenicity was observed due probably to the more porous structure of blend membrane. These results demonstrated that the hemocompatibility would be improved for PAN/PVDF blend membranes with appropriate hydrophilicity and roughness. Copyright © 2005 John Wiley & Sons, Ltd.     

The effect of heat treatment of PES and PVDF ultrafiltration membranes on morphology and performance for milk filtration

The flat sheet polyethersulfone (PES) and poly(vinylidene fluoride) (PVDF) membranes were prepared by immersion precipitation technique. The influence of hot air and water treatment on morphology and performance of membranes were investigated. The membranes were characterized by AFM, SEM, cross-flow filtration of milk and fouling analysis. The PES membrane turns to a denser structure with thick skin layer by air treatment at various temperatures during different times. This diminishes the pure water flux (PWF). However the milk permeation flux (MPF) was considerably improved at 100 °C air treatment for 20 min with no change in protein rejection. The smooth surface and slight decrease in surface pore size for air treated PES membrane at 100 °C compared to untreated membrane may cause this behavior for the membrane. The water treatment of PES membranes at 55 and 75 °C declines the PWF and MPF and increases the protein rejection. This is due to slight decrease in membrane surface pore size. The treatment of PES membrane with water at higher temperature results in a porous structure with superior performance. The fouling analysis of 20 min treated membrane indicates that the surface properties of 100 °C air treated and 95 °C water treated PES membranes are improved compared to untreated membrane. The SEM observation depicts that the morphology of air and water treated PVDF membranes was denser and smoother with increasing the heat treatment temperature. The 20 min air treated PVDF membranes at 100 °C and water treated at 95 °C exhibited the highest performance and antifouling properties.