Hydrophilic microporous PES membranes prepared by PES/PEG/DMAc casting solutions

Microporous poly(ether sulfones) (PES) membranes were prepared via phase inversion using poly (ethylene glycol) (PEG) as additive and N,N‐dimethylacetamide (DMAc) as solvent. Thermodynamic of the casting solutions was studied by coagulation value while precipitation rate was observed by light transmittance measurement. It was found that casting solution with PEG200 as additive was thermodynamically less stable than those with PEG400 and PEG600 as additive and easier to cause phase separation in exposure time. With the increase of PEG200 concentration, the casting solution became thermodynamically less stable and easier to cause phase separation in exposure time, but precipitation rate during immersion precipitation decreased because of the increased viscosities. ATR‐FTIR spectra and TGA curves showed that the membranes prepared using PEG200 as additive had less PEG residual than those of PEG400 and PEG600, but it showed better permeation performance than that prepared using PEG400 and PEG600 as additive. With the increase of PEG200 concentration from 30 to 70 wt %, the cross section structure changed from macrovoid to sponge‐like, micropores with a mean pore size around 0.1 μm began to form on the top surface. When the PEG200 concentration is 60 wt %, the pure water flux was 1845 L m^?2 h^?1 bar^?1, which is the highest value. As the PEG200 concentration increased from 30 to 60 wt %, the contact angles decreased from 82.1° to 58.2°. As the addition amount of PEG200 increased, the residual PEG made the prepared membranes more hydrophilic. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Small angle neutron scattering study of structural aspects of nonionic surfactants (Tween 20 and Tween 80) in the presence of polyethylene glycols and triblock polymers

Small angle neutron scattering (SANS) technique has been used to study the micellar behavior of nonionic surfactants, Tween 20 and Tween 80 with additives like polyethylene glycols (PEG with molecular mass 400, 6000, and 15,000) and triblock polymers (TBPs) of varying composition. Surfactant‐additive interactions have been explained on the basis of parameters like aggregation number (N_agg), core radius (R_c), hard sphere radius (R_hs), volume fraction (ϕ) and axial ratio (b/a). The SANS analysis indicate the reduction in values of N_agg of Tween on addition of PEG additive. Shape of Tweens (3 wt %) micelles in the presence of PEG (10 wt %) is found to oblate ellipsoidal. Similarly, the shape of Tween (3 wt %) micelles is oblate ellipsoidal at low concentration of TBPs (1 wt %); however, they become spherical as the concentration of TBP increases to 10 wt %. The shape of micelles of pure TBPs also comes out to be spherical. Results reflects that at low concentration of TBP shape is controlled by surfactant (Tween 20 and Tween 80) while at high concentration of TBP shape of mixed micelle is controlled by TBP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Droplet size and morphology for the aqueous two‐phase polymerization of acrylamide in an aqueous poly(ethylene glycol) solution

A kind of polyacrylamide (PAM) latex product dispersed in an aqueous solution was successfully prepared through the aqueous two‐phase polymerization of acrylamide in an aqueous solution of poly(ethylene glycol) (PEG). The effects of various polymerization parameters on the size and morphology of droplets rich in PAM were systematically investigated. The droplet size and morphology was significantly influenced by the polymerization rate. The high polymerization rate caused the formation of stripe‐shaped droplets because of the aggregation of more droplets rapidly separated from the continuous phase. At the same time, the monomer partition behavior mainly relied on the temperature, and the PEG concentration also dramatically affected the droplet size and morphology. The increase in PEG concentration not only changed the monomer partition behavior and restrained droplet aggregation but also shortened the critical PAM radical chain length and accelerated the droplet formation. Furthermore, the stirring speed was also recognized as the correlative factor that affected the droplet stability and monomer diffusion rate from the continuous phase into the droplets. The addition of salt and alcohol altered the droplet stability and the final droplet size and morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚乙二醇为分散剂制备纳米生物活性玻璃粉体

采用溶胶-凝胶共沉淀方法结合冷冻干燥技术制备颗粒尺寸在纳米级的生物活性玻璃(NBG),研究了加入分散剂聚乙二醇(PEG-10000)对玻璃颗粒的分散性能、微观形貌和生物活性的影响.结果表明:没有加入PEG制得的纳米生物活性玻璃颗粒呈现不规则形态,粒径小于50 nm.加有PEG的玻璃颗粒形状趋于规则的球形,分散性大大提高,颗粒粒径在40～100 nm,而且加入PEG的浓度越高,制备的颗粒粒径越小.通过比较纳米级的生物活性玻璃与溶胶-凝胶生物活性玻璃在模拟人体体液(SBF)中的表面矿化研究,发现纳米生物活性玻璃比溶胶-凝胶生物活性玻璃有更高的生物活性.     

Enhancing the CO2 Separation Performance of Matrimid 5218 Membranes for CO2/CH4 Binary Mixtures

The effect of CO₂‐philic additive polyethylene glycol (PEG) 200 in Matrimid 5218 on the separation performance of prepared membranes was evaluated in a binary gas mixture. Matrimid/PEG 200 flat‐sheet blended membranes with low PEG concentrations were prepared by the dense film‐casting method. Pure Matrimid and blended membranes were characterized by FTIR spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and permeation measurements. The addition of 4–5 % of PEG enhanced considerably the CO₂ permeability of the Matrimid matrix. The best formulation, Matrimid/PEG 200 (96/4), showed in comparison to pure Matrimid a more than threefold increase in CO₂ permeability and an increase in separation factor of about 40 %.     

Characterization of cellulose triacetate membranes, produced from sugarcane bagasse, using PEG 600 as additive

Cellulose Acetate (CA) produced from sugarcane bagasse cellulose was used to produce membranes, using poly(ethylene glycol) (PEG 600) as additive. Results showed that PEG 600 was washed out the membranes during the preparation step. Thermal Analysis showed that the temperature of degradation of the membranes increased in 10 °C when PEG 600 was added to the composition, but did not change as more PEG 600 was added in the composition. On the other hand, the crystalline content (%C) of the membranes increased as PEG 600 was added. The addition of PEG 600 also increased the resistance of the membranes to pressure and the pure water flux rate, but membranes produced with PEG 600 content lower than 5% did not present water flux. PEG 600 also increased the coefficient of ion diffusion of the membranes.     

Preparation of porous PVC membrane via a phase inversion method from PVC/DMAc/water/additives

Poly(vinyl chloride) membranes were prepared via a phase inversion method, using N,N‐dimethylacetamide (DMAc) as solvent, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and sucrose as three typical additives and water as the coagulation medium. The phase diagrams of the PVC/DMAc/additives/water quaternary systems were constructed using cloud‐point experimental data. With the addition of the different additives, the effect of dope solution temperature on the dope solution viscosity and the structure of membranes were investigated. It indicates that the viscosity of the PVC/DMAc dope solution with the additive increase compared with the dope solution without any additive and the addition of the additives into the dope solution alter the morphology and structure of the resultant membranes during the phase‐inversion process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reentrant phase transition and fast responsive behaviors of poly{N‐[3‐(dimethylaminopropyl)] methacrylamide} hydrogels prepared in poly(ethylene glycol) solutions

Macroporous temperature‐sensitive poly {N‐[3‐(dimethylaminopropyl)] methacrylamide} hydrogels were synthesized by free‐radical crosslinking polymerization of the monomer N‐[3‐(dimethylaminopropyl)] methacrylamide and the crosslinker N,N′‐methylenebisacrylamide in aqueous solutions at 22°C. Poly(ethylene glycol) (PEG) with a molecular weight of 1000 g/mol was used as the pore‐forming agent during the polymerization reaction. The concentration of PEG in the polymerization solutions was varied between 0 and 18 wt %, whereas the crosslinker (N,N′‐methylenebisacrylamide) concentration was fixed at 2 wt % (with respect to the monomer). The effects of the PEG concentration on the thermo‐induced phase‐transition behavior and the chemical structure, interior morphology, and swelling/deswelling kinetics were investigated. Normal‐type hydrogels were also prepared under the same conditions without PEG. An interesting feature of the swelling behavior of both the normal‐type and macroporous hydrogels was the reentrant phase transition, in which the hydrogels collapsed once and reswelled as the temperature was continuously increased. Scanning electron micrographs revealed that the interior network structure of the hydrogels prepared in PEG solutions became more porous with an increase in the PEG concentration in the polymerization solution. This more porous matrix provided numerous water channels for water diffusion in or out of the matrix and, therefore, an improved responsive rate to external temperature changes during the deswelling and swelling processes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of porous poly(vinylidene fluoride) membranes for dehumidification with poly(ethylene glycol) as an additive

Porous poly(vinylidene fluoride) (PVDF) membranes for dehumidification were prepared from a PVDF/dimethylformamide/water system by phase inversion with poly(ethylene glycol) (PEG) as an additive at various concentrations (1.2, 1.8, and 2.4%) and with various molecular weights (1000, 2000, and 6000). The surface morphologies of the resultant membranes were characterized with scanning electron microscopy and atomic force microscopy, and the pore diameter, porosity, and pore size distribution of the membranes were also determined by a gas‐sorption method. The influence of the concentration and molecular weight of PEG on water‐vapor transport through the membranes was evaluated. The moisture‐transport property of the membranes was improved significantly with increases in the concentration and molecular weight of PEG, and a membrane with good moisture permeability was obtained with 2.4% PEG‐6000 as an additive. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

添加剂聚乙二醇对堇青石蜂窝陶瓷载体γ-Al_2O_3涂层性能的影响

以拟薄水铝石为原料,硝酸为胶溶剂,添加聚乙二醇(PEG)制备铝溶胶,并对堇青石蜂窝陶瓷载体进行γ-Al2O3涂层。考察了不同分子量(400,6000和20000)聚乙二醇的添加对溶胶黏度,粒径分布以及涂覆涂层负载量和重现性的影响;利用BET法测定了溶胶中添加不同分子量的聚乙二醇后,涂层比表面积的变化;超声波振荡检测了堇青石蜂窝陶瓷载体涂层的结合牢固性;由SEM照片观察涂层的表面形貌。结果表明,聚乙二醇的添加,增大了溶胶的黏度,提高了载体涂层的负载量、比表面积和结合牢固度。添加剂聚乙二醇分子量的不同对溶胶和载体涂层性能的影响也不同,聚乙二醇20000的添加使溶胶黏度和涂层负载量的增加程度更明显,而添加聚乙二醇400制备溶胶的粒径小,分布范围窄,涂覆涂层均匀、牢固且比表面积大。     

Effect of additive and current mode on surface morphology of palladium films from a non-aqueous deep eutectic solution (DES)

Electrodeposition of palladium from a non-aqueous electrolyte solution [choline chloride/urea/palladium(II)chloride] has been carried out by direct and pulse current electroplating. In this study, the influence of an organic additive (nicotinic acid amide), current mode (direct current or pulse current deposition) and hydrodynamic on the surface morphology of electroplated palladium films was investigated. In order to determine the surface morphology and thickness of the electrodeposited palladium layers, a scanning electron microscope and an energy dispersive X-ray fluorescence spectroscope were used. In addition, the cell voltage during the different electrodeposition experiments was recorded and analysed. The experimental results showed that the surface morphology of the palladium deposits could be remarkably affected either by addition of the additive or by applying pulse current. Pulse plating and the selected inhibitor mutually interfere with each other, causing changes in the microstructure of the palladium deposits (e.g. smoothening or forming of micro-cracks). It was possible to optimise the palladium deposit quality by applying pulse current or by addition of the appropriate inhibitor.     

Preparation and characterization of poly(vinyl chloride)/polystyrene/poly(ethylene glycol) hollow‐fiber ultrafiltration membranes

Hollow‐fiber ultrafiltration (UF) membranes were prepared from blends of poly(vinyl chloride) (PVC) and polystyrene (PS) with a dry/wet phase inversion method. Poly(ethylene glycol) (PEG) and N,N‐dimethylacetamide were used as the additive and solvent, respectively. The effects of the PEG concentration in the dope solution as an additive on the cross sections and inner and outer surface morphologies, permeability, and separation performance of the hollow fibers were examined. The mean pore size, pore size distribution, and mean roughness of both the inner and outer surfaces of the produced hollow fibers were determined by atomic force microscopy. Also, the mechanical properties of the hollow‐fiber membranes were investigated. UF experiments were conducted with aqueous solutions of poly(vinyl pyrrolidone) (PVP; K‐90, M_w = 360 kDa). From the results, we found that the PVC/PS hollow‐fiber membranes had two layers with a fingerlike structure. These two layers were changed from a wide and long to a thin and short morphology with increasing PEG concentration. A novel and until now undescribed shape of the nodules in the outer surfaces, which was denoted as a sea‐waves shape, was observed. The outer and inner pore sizes both increased with increasing PEG concentration. The water permeation flux of the hollow fibers increased from 104 to 367 L m^?2 h^?1 bar^?1) at higher PEG concentrations. The PVP rejection reached the highest value at a PEG concentration of 4 wt %, whereas at higher values (from 4 to 9 wt %), the rejection decreased. The same trend was found also for the tensile stress at break, Young's modulus, and elongation at break of the hollow fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 989‐1004, 2013     

添加剂对喷射电沉积纳米晶Co-Ni合金的影响

在氯化镍-硫酸钴体系电解液中采用添加剂喷射电沉积纳米晶Co-Ni合金,测定了其阴极极化曲线.研究了添加剂对阴极过电位、电流效率、镀层中Co含量、镀层的相结构、晶粒尺寸、表面形貌及显微硬度、软磁性能等影响.结果表明:添加剂增加了极化作用,影响了Co、Ni电沉积的动力学过程.当添加剂为2.5g/L时,与未加添加剂相比较,阴极过电位从3.594V增大到4.755 V,电流效率和沉积层中Co含量变化不大,但沉积层晶粒尺寸从12.8 nm明显降低到5.5 nm,维氏硬度从423升高到511,同时Co-Ni合金的软磁性能得以提高.     

聚乙二醇4000对硫酸钡微粒形貌的调控作用

以水溶性高聚物聚乙二醇4000（PEG4000）为分散剂,研究了反应方式、聚乙二醇浓度、钡离子与硫酸根物质的量比等因素对硫酸钡微粒形貌和晶体结构的影响,通过扫描电镜（SEM）、透射电镜（TEM）、X射线粉末衍射（XRD）等手段对合成样品的形貌和结构进行了表征。结果表明,反应体系经陈化和回流过程,均有利于硫酸钡微粒“溶解与再生长过程”的发生,易于得到较大尺寸的硫酸钡微粒;随着聚乙二醇浓度的增加,所得硫酸钡晶体的形貌呈现从十字花形经片状向棒状结构的显著变化,且在合适聚乙二醇浓度时可以得到具有良好光泽性能的片状硫酸钡单晶结构。钡离子与硫酸根物质的量比的改变也能影响硫酸钡微粒的形貌而得到新颖的“鱼骨刺”形的纳米结构。     

Synthesis and micellar characterization of luteinizing hormone‐releasing hormone poly(ethylene glycol)‐block‐poly(l‐histidine) copolymers

A facile and well‐controlled pathway was introduced to obtain optimal pH‐sensitive luteinizing hormone‐releasing hormone—functionalized poly(ethylene glycol)‐block‐poly(l ‐histidine) (LHRH‐PEG‐PHIS) micelles in this paper. The influence of block‐selective solvent, the weight ratio of the selective solvent to common solvent and initial polymer concentration on the self‐assembly of LHRH‐PEG‐PHIS micelles were studied. These factors exerted remarkable influence on the morphology of the resulting micelles. The micelles showed a spherical geometry and an uniform appearance under the following optimal experimental conditions: LHRH‐PEG/PHIS ratio of 1.0 by molar, DMF as the selective solvent and 3.0 mg/mL as initial concentration, 100 W of ultrasonic power. These micelles had a small diameter (about 90 nm), low CMC (10 μg/mL), and pH‐sensitive switch in surface charge and micelles' size. As the pH of the micellar solution decreased from pH 7.4 to 5.5, the zeta potential of the LHRH‐PEG‐PHIS micelles increased from ?0.02 mV to 20.7 mV and the diameter of the nanoparticles decreased from 137 nm to 76 nm. After 30 h of incubation at pH 5.0, 6.0, and 7.4 the released free Doxorubicin (DOX) was about 83.18%, 81.26%, and 30.35%, respectively. The LHRH‐PEG‐PHIS micelles could combine the characteristics of active targeting with pH‐triggered drug release promising as intracellular drug delivery carriers. POLYM. ENG. SCI., 55:277–286, 2015. © 2014 Society of Plastics Engineers     

Photo‐induced protonation and conductivity of polyaniline/poly(ethylene glycol) and polyaniline/[poly(ethylene glycol)‐grafted polyaniline] composites

Composites of polyaniline in its emeraldine base form (PANI‐EB) and photo‐acid generators (PAG) show an increase in conductivity upon photo‐irradiation due to the protonation of PANI‐EB. Such materials may be utilized to fabricate conducting patterns by photo‐irradiation. However, the conductivity obtained by direct irradiation of PANI‐EB/PAG composites was normally quite low (<10^?3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), which is a proton transfer polymer, was added to PANI‐EB/PAG. Results showed that addition of low M_w (550) PEG significantly enhance the photo‐induced conductivity. Conductivities as high as 10^?1–10⁰ S/cm were observed after photo‐irradiation. This conductivity is comparable to that of PANI‐salt synthesized by oxidizing aniline in the presence of an acid. High M_w (8000) PEG is much less effective than PEG 550, which is attributed to its lower compatibility with PANI. PEG‐grafted PANI (N‐PEG‐PANI) was also studied as an additive. Composites of PANI‐EB and N‐PEG‐PANI showed conductivity as high as 10² S/cm after treatment with HCl vapor. The photo‐induced conductivity of the N‐PEG‐PANI/PANI‐EB/PAG composite reached 10^?2–10^?1 S/cm. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Non‐isothermal crystallization of poly(ethylene oxide)/silver nanoplate composites

The non‐isothermal crystallization of poly(ethylene oxide) (PEO)/silver nanoplate composites was studied using differential scanning calorimetry. The non‐isothermal crystallization was analyzed by combining the Avrami and Ozawa equations. It was found that the Avrami exponent for neat PEO ranges from 2.51 to 2.53, whereas it ranges from 2.54 to 3.16 for its composites, indicating that the spherical crystal morphology does not change with the addition of nanoplates. However, the rate determination of crystal growth transfers from diffusion to nucleation. The crystallization half‐time showed an increase with the addition of silver nanoplates in PEO, indicating that the overall crystallization rate of PEO decreases with the addition of nanoplates. However, the nucleation activity is larger than unity in the composites and the value increases with an increase in the nanoplate content. This behavior implies that the nanoplates act as anti‐nucleating agents to hinder nucleation. Copyright © 2011 Society of Chemical Industry     

凝固条件对聚砜-聚乙二醇超滤膜结构和性能的影响研究

以不同相对分子质量及含量的聚乙二醇(PEG)作添加剂制备聚砜(PSF)超滤膜,并考察它们对膜水通量、截留率、机械强度的影响.结果表明,添加剂PEG相对分子质量的提高可显著改善膜通量,提高PEG含量会改变铸膜液体系的相平衡关系,加速相分离的发生,在一定范围内随着PEG含量的提高,膜通量逐渐增大,当PEG的质量分数为15%...     

Pd/Co Bimetallic Nanoparticles: Coelectrodeposition under Protection of PVP and Enhanced Electrocatalytic Activity for Ethanol Electrooxidation

A series of Pd–Co bimetallic nanostructures with Co compositions ranging from 0 to 13 at.% were fabricated on glassy carbon electrode by one step electrodeposition in the presence of polyvinylpyrrolidone (PVP). The roles of PVP and Co have been systematically investigated by using combined techniques such as scanning electron microscopy, energy dispersive spectrometry, cyclic voltammetry, X‐ray diffraction, and chronoamperograms. PVP was used as an additive to stabilize the Pd nanoparticles and inhibit agglomeration during their formation. The prepared Pd₁₀₀Co₁₀ bimetallic nanostructures exhibited great catalytic activity towards ethanol oxidation in alkaline, which implies that low Co doping can be a convenient way to enhance the electrocatalytic property of Pd. The present study shows that the Pd/Co bimetallic nanoparticulate can be a promising catalyst for portable applications in direct ethanol fuel cell in alkaline solution.     

添加剂作用下阿司匹林结晶模拟和实验研究

晶体形貌作为晶体产品的重要质量指标,不仅会影响产品流动性、稳定性、溶出速率和生物可利用度等产品的质量指标,还会对过滤、干燥、压片等下游操作造成影响。通过分子模拟的方法指导阿司匹林冷却-反溶剂结晶过程的添加剂筛选,以添加剂作为晶体形貌的改性剂,降低阿司匹林晶体的长径比优化晶体形貌。通过单因素实验考查了添加剂浓度、晶种加入量、降温速率、搅拌速率和加水速率对阿司匹林晶体产品形貌、流动性和粒度分布等的影响,确定了较优的工艺条件。实验结果表明加入聚乙烯吡咯烷酮（PVP）作为添加剂可以降低阿司匹林晶体长径比,获得形貌为短棱柱状的晶体产品,能够显著改变晶体形貌优化产品的流动性。