Use of Different Salt Solutions in Salting-Out TLC of Co(III) Complexes on Silica Gel

Saturated aqueous solutions of 28 different salts have been studied as a potential mobile phases for salting-out thin-layer chromatography, on silica gel, of a series of four mixed bis-aminocarboxylato cobalt(III) complexes. In addition, by linear regression analysis of chromatographic data obtained for fifteen mixed aminocarboxylato Co(III) complexes (four series) with solutions of ammonium chloride, three alkali metal chlorides, and four alkaline earth metal chlorides, four linear dependences previously established on different adsorbents with (NH₄)₂SO₄ solutions were confirmed. The qualities of the separations achieved with the salts were compared and Li⁺, Mg²⁺, and Ca²⁺ chlorides are proposed as the most suitable.     

Salting-out thin-layer chromatography of transition metal complexes. IV: Effect of sorbent on the behaviour of mixed aminocarboxylato cobalt (III) complexes

Summary From literature data for 14 mixed aminocarboxylato cobalt(III) complexes, the effect of the sorbent on R_M values, salting-out efficiency (m) and separation factors () of adjacent members of homologous series was investigated in salting-out, thin-layer chromatography on silica gel, polyacrylonitrile and cellulose sorbents, using ammonium sulphate solutions as developers. For complexes belonging to the same homologous series, linear dependence was found between R_M,m and log values, respectively, on two different sorbents. Polyacrylonitrile was shown to be the most suitable sorbent for the separation of the complexes since it gave the highest values for R_M,m and .     

Micellization and Thermogelation of Poly(ether urethane)s Comprising Poly(ethylene glycol) and Poly(propylene glycol)

A series of multiblock poly(ether urethane)s comprising poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized. Their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 8 to 12 wt%. The composition and structural information of the copolymers were studied by GPC and ¹H NMR. The critical micellization concentration (CMC) and thermodynamic parameters for micelle formation were determined at different temperatures. The temperature response of the copolymer solutions were studied and found to be associated with the composition of the copolymers.     

Poly(ethylene glycol) Surface Coated Magnetic Particles

Summary: A methacrylate‐functionalized poly(ethylene glycol) macromonomer was copolymerized at the surface of methacrylate‐derivatized maghemite nanoparticles. After silylation of the magnetic core with methacryloxypropyltrimethoxysilane, two grafting procedures based on either a direct copolymerization reaction in water or an inverse emulsion polymerization were compared. A direct copolymerization led to low polymer surface amounts, whereas an inverse emulsion process allowed nanocomposite particles containing up to 90 wt.‐% polymer to be obtained.

TEM picture of maghemite‐PEG hybrid particles.     

聚乙二醇中1-辛炔的环三聚反应

在绿色反应介质聚乙二醇中,PdCl2／CuCl2催化体系可以顺利地催化1-辛炔发生环三聚反应,区域选择性地生成1,3,5-三己基苯,该反应产率较高,对环境友好,且催化体系可以适当地重复使用．     

Poly(2‐ethyl‐2‐oxazoline) as Alternative for the Stealth Polymer Poly(ethylene glycol): Comparison of in vitro Cytotoxicity and Hemocompatibility

Limitations of PEG in drug delivery have been reported from clinical trials. PEtOx (0.4–40 kDa) as alternative is synthesized by a living, microwave‐assisted polymerization, and is directly compared to PEG of similar molar mass regarding cytotoxicity and hemocompatibility. In short‐term treatments, both types of polymers are well tolerated even at high concentrations. Moderate concentration and molar mass dependent cytotoxic effects occurred only after long‐term incubation at concentrations higher than therapeutic doses. PEtOx possesses not only an easy route of synthesis and beneficial physicochemical characteristics such as low viscosity and high stability, which are advantageous over PEG, but additionally in vitro toxicology comparable to PEG.

     

Electrostatic Assembly of Poly(ethylene glycol) Nanotubes

Poly(ethylene glycol) (PEG)‐based films, nanotubes, and nanotube arrays were successfully made using layer‐by‐layer (LbL) assembly ion‐containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155 nm. The PEG‐based structures showed remarkable stability in water, salt water, and sodium hydroxide solution.

     

Super Molecular-polarization Phenomenon of Poly (ethylene glycol) in Deionized Water

A new discovery describing nonionic surfactant poly(ethylene glycol) being added into deionized water, electrical conductivity of the water would show a remarkable increase phenomenon. The mechanism study indicated that the electrical conductivity increase of the water doped some PEG was formed by super-polarization of a PEG molecule on the water molecule. A PEG molecule can form a super polarization body in the water, which will generate a strong polarization effect on the water molecule, thereby increasing water ionization degree and makes the electrical conductivity of water greater.     

Synthesis and Characterization of Calix[4]arene Functionalized Poly(ethylene glycol) Derivatives

Calix[4]arenes with both ligating and methoxy poly(ethylene glycol) groups appended have been synthesized using several approaches, involving the formation of sulfonyl ester groups on the wide rim, Schiff base derivatives on the narrow rim, and thioether groups on both the wide and narrow rims. These new derivatives have been characterized by a combination of infrared and ¹H NMR spectroscopy. Compounds 10 and 11 are insoluble in both water and aqueous poly(ethylene glycol), but the other new compounds are soluble.     

Synthesis and Characterization of Poly(ethylene glycol) Dimethacrylate Hydrogels

Facile synthesis and detailed characterization of photo-polymerizable and biocompatible poly(ethylene glycol) dimethacrylates (PEGDM) and their hydrogels are described. Combined analyses of ¹H NMR and MALDI-TOF MS confirmed the formation of prepolymers of high purity and narrow mass distribution (PD < 1.02). A systematic investigation into the structure and mechanical properties of PEGDM hydrogels was performed to characterize the relationships between the network structure and gel properties. Small-angle neutron scattering was used to characterize the structural features of hydrogels with respect to their semidilute solution precursors. A well-defined structural length scale (correlation length) manifested as a maximum in the scattering intensity was observed for hydrogels derived from high molecular mass PEGDMs and/or high oligomer mass fractions. Hydrogels derived from lower molecular mass PEGDMs and/or low oligomer mass fractions exhibited multiple correlation lengths suggesting the formation of inhomogeneous gel structures. The shear moduli, determined from uniaxial compression measurement, showed that the gel structures correlate well with the gel mechanical properties.     

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis,characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m² hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.     

Mathematical Model for Surface‐Initiated Photopolymerization of Poly(ethylene glycol) Diacrylate

Summary: A general mathematical model has been developed to describe the surface initiated photopolymerization of PEG‐DA forming crosslinked hydrogel membranes upon the surface of a substrate. Such membranes are formed by photopolymerizing a PEG‐DA prepolymer solution by initiation with eosin‐Y‐functionalized surfaces and TEA using VP as accelerator. Experimental measurements of the thickness of hydrogel membranes compare well with the model. The model is developed by using the pseudo‐kinetic approach and the method of moments, and is capable of predicting the crosslink density and thickness of the hydrogel membrane. Parametric sensitivity of the effects of PEG‐DA, VP and coinitiator TEA concentration towards the crosslink density and the thickness of the hydrogel is also investigated. The results obtained for different PEG‐DA and VP concentrations suggest that the concentration ratio of these two monomers is a key parameter in controlling the gel thickness and permeability. This model can also be applied to systems where drugs, proteins or cells are encapsulated through surface initiated photopolymerization to predict the growth and crosslink density profiles of the encapsulating membrane. In a previous study we have experimentally demonstrated that these membranes could be made to attach covalently to the surface of the underlying substrate.

Comparison of experimental measurements and model simulation of PEG‐DA hydrogel membrane thickness versus laser duration at high PEG‐DA concentrations.     

Thermo-Responsive Hydrogels Based on Branched Poly(L-lactide)-poly(ethylene glycol) Copolymers

Summary: Branched poly(L -lactide)-poly(ethylene glycol) (PLLA-PEG) block copolymers were synthesized from trifunctional PLLA and amine functionalized methoxy poly(ethylene glycol)s. The copolymers in water formed hydrogels that showed thermo-responsive behavior. The hydrogels underwent a gel to sol transition with increasing temperature as determined with the vial tilting method and oscillatory rheology. For all copolymers, the transition temperature increased with increasing copolymer concentration. The transition temperature of corresponding branched copolymers also increased with increasing PEG molecular weight, and surprisingly decreased with increasing molecular weight of the PLLA branches. In general, the gel-sol transition is explained by disruption of micellar or aggregate interactions because of partial dehydration and shrinkage of the PEG chains. An increase in the molecular weight of the PLLA branches led to the formation of micelles and aggregates as observed with DLS at low concentrations. It is speculated that the non-uniform size distribution and possible crystallization of longer PLLA blocks may have a negative effect on the formation of micellar packing upon gelation, allowing the disruption of micellar or aggregate interactions to occur at lower temperatures. The transition temperature of the gels could be tuned closely to body temperature by varying the concentration of the solution or the molecular weight of the PEG block and the PLLA blocks, which implies that these polymers may be used as injectable systems for in-situ gel formation.     

Determination of Iodide and Thiocyanate in Seawater by Liquid Chromatography with Poly(ethylene glycol) Stationary Phase

Novel, simple, rapid, highly sensitive, and direct determination of iodide and thiocyanate ions in seawater has been performed by liquid chromatography (LC) with UV detection at 220 nm. The separation was achieved on a C₃₀ column of conventional size (150 mm × 4.6 mm i.d.) modified with poly(ethylene glycol); an aqueous solution of 300 mM sodium sulfate and 50 mM sodium chloride was used as mobile phase. Detection limits (S/N=3) obtained by injecting a 20-L sample were 0.5 and 6 ng mL^–1 for iodide and thiocyanate, respectively. The method was successfully used for rapid and direct determination of iodide and thiocyanate in seawater samples, collected from the coasts of Japan, without any extra pretreatment.Dedicated to Professor K. Jinno on the occasion of his 60^th birthday     

Adsorption-desorption of Silica Nanoparticles on Poly(ethylene glycol) Brushes Grafted onto Au Substrate Studied by Quartz Crystal Microbalance

The adsorption-desorption of silica nanoparticles(NPs) on poly(ethylene glycol)(PEG) grafted onto gold(Au) substrate was studied by quartz crystal microbalance with dissipation monitoring(QCM-D) technique. The results of frequency and dissipation show that SiO₂ NPs can be adsorbed strongly on PEG-SH brushes at pH of 9.6, and a new dense and rigid construction is formed. Adjusting the pH from 9.6 to 12.3 resulted in the desorption of silica NPs from the PEG brushes because of a significant weakening of the hydrogen bond between the silica NPs and PEG chains. In addition, the viscoelastic properties of the system during the adsorption-desorption process were also analyzed via the relationship between the normalized frequency(Δf/n) and mass. And the corresponding atomic force microscopy(AFM) images also exhibit morphological changes during the above process, consistent with the changes in viscoelasticity.     

新型结合阿霉素的聚乙二醇嵌段共聚树枝状聚赖氨酸的合成及其药物缓释行为的研究

采用液相多肽合成方法, 成功制备得到窄分子量分布、结构确定的聚乙二醇嵌段共聚四代树枝状聚赖氨酸 (MPEG-block-DPL4). 在此基础上, 进一步将其DPL4的端氨基转化为端肼基, 并通过其与抗肿瘤药物阿霉素(DOX) C＝O的反应形成C＝N键, 实现在DPL4表面的阿霉素药物分子化学结合, 最终得到新型pH敏感性的高分子药物MPEG-block-DPL4-CONHN＝DOX. 运用紫外分光光度(UV-Vis)法, 对MPEG-block-DPL4-CONHNH₂与阿霉素的负载效率进行了定量分析. 高分子药物MPEG-block-DPL4-CONHN＝DOX在生理条件(pH＝7.4)下相对稳定, 而弱酸性条件(pH＝4.5, 5.5)下, C＝N键能较快水解, 释放阿霉素药物分子. 体外细胞毒性评价结果表明(细胞株SMMC-7721和SPCA-1), 所得新型高分子药物MPEG-block-DPL4-CONHN＝DOX的细胞毒性显著地低于游离阿霉素药物分子, 因此, 可进一步研究发展成为新型pH敏感性可控缓释高分子抗肿瘤药物载体体系.     

PEG／PED-g-CB化学敏电阻材料的制备及其气敏性能的研究

以不同分子量聚乙二醇(PEG)为基体，PEG接枝改性的炉法炭黑(PEG-g-CB)为导电裁流子，采用溶液分散工艺制得一种新鞭的气敏传感器材料。研究了PEG分子量对接枝率及对各种溶剂蒸气的响应性、响应灵敏度的影响；用透射电子显微镜(TEM)和紫外—可见分光光度计考察了两种炭黑粒子分散行为、袁面特性差异及其对响应重复性、稳定性的影响。结果表明，PEG／PEG-g-CB复合材料化学敏电阻体对其良溶剂蒸气如THF、氯仿、丙酮具有很强的响应性，其电阻值可提高到初始电阻的10^4～10^6倍。将这种材料再放入干燥空气中时，电阻又恢复到初始值；而对其不良溶剂如正己烷、甲苯几乎不响应。随PEG分子量的提高，响应灵敏度下降；响应的重复稳定性受炭黑粒子分散行为的影响，从聚合物溶胀行为及逾渗导电理论解释了实验结果。