Interaction of sodium dodecyl sulfate with polyelectrolyte complexes derived from diazoresin and sulfonate-containing polymers

The sulfonate-containing polyelectrolytes (SPE) from sulfonation of polystyrene (PS) and copolymerization of 3-sulfo-propyl methacrylate, potassium salt (SPMS) with styrene (S) were prepared. Photosensitive polyelectrolyte complexes (PEC_DR) derived from SPE and diazoresin (DR), which does not dissolve in water or organic solvent due to its ionic crosslinking structure, dissolves in aqueous solution of sodium dodecyl sulfate (SDS) due to the dissociation of PEC_DR and the hydrophobic interaction between SDS and the polymer chain. The photosensitive behavior and thermostability of the PEC_DR were investigated, and it was found that the thermostability of PEC_DR increases dramatically in SDS aqueous solution. It was proposed that the higher thermostability of PEC_DR in SDS aqueous solution is due to an aggregation of SDS molecules around the diazonium group of the PEC_DR, which protects the  N group of the DR from attack by the nucleophiles. The image-forming behavior of PEC_DR by ultraviolet (UV) light was examined and considered to be different from other PECs. It was concluded that the photoimaging behavior of PEC_DR is based on a reaction in which an ionic bond converts to a covalent bond. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2601–2606, 1999     

Kinetics of redox polymerizations of acrylic acid in inverse dispersion and in aqueous solution

Redox polymerizations of acrylic acid in inverse dispersion and in aqueous solution (with surfactant) were conducted by using sodium metabisulphite/potassium bromate initiators. The monomer conversions were determined by using high‐performance liquid chromatography, and the polymer particles in the final lattices were examined using a scanning electron microscope with freeze‐fracture equipment. Experimental rate expressions implied that complex reactions are involved in the redox polymerizations. A chemical reaction scheme was proposed, and kinetic models were developed for the redox polymerization in aqueous solution. Comparison between the experimental rate expressions and the kinetic models suggested a combination of bimolecular and monomolecular termination modes, a chain transfer function of the surfactant, and an oxidizing role of the oxygen molecules. The differences in the experimental rate expressions between the redox polymerization in inverse dispersion and that in aqueous solution are in good agreement with the kinetic model predictions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 313–324, 1999     

New synthesis of liquid polysulfide polymers in the presence of hydrazine. II. The synthesis of linear polymers from 1,1′-[methylenebis(oxy)]-bis-[2-chloroethane] and Na2S3 or Na2S2.5

Liquid polysulfide polymers with the thiol groups on the end of the chains and of the average molecular weight of 7000–510 g mol⁻¹ have been obtained by the reaction of BClE and Na₂S₃, i.e., Na₂S_2.5 in the presence of hydrazine. The average molecular weight of the obtained polymers depends on the quantity of hydrazine used for the syntheses. With the aim to obtain polymers of the similar average molecular weight it is necessary to use on average 0.5 mol of hydrazine per polymer segment less if Na₂S_2.5 is used instead of Na₂S₃. The sulfur content in the obtained polymers is on average less than 2 sulfur atoms per polymer segment and amounts to 1.90 sulfur atoms when Na₂S₃ is used and is 1.76 sulfur atoms per polymer segment when Na₂S_2.5 is used for the synthesis. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1369–1373, 1997     

Direct carboxylation reaction of methane with CO by a Yb(OAc)3/Mn(OAc)2/NaClO/H2O catalytic system under very mild conditions

A new method of synthesis of acetic acid in water has been developed from the carboxylation of methane with carbon monoxide using lanthanide catalysts. Ytterbium(III) acetate has been found to be the most active catalyst among the compounds of the lanthanide series in the carboxylation reaction of methane with carbon monoxide. Sodium hypochlorite or hydrogen peroxide was used as the oxidant in this reaction. Sodium hypochlorite exhibited more favorable activity than hydrogen peroxide in the reaction. The catalytic activity was improved by the addition of transition-metal salts such as manganese(II) acetate. The best result has been found at a ratio of manganese(II) acetate to ytterbium(III) acetate of 1:10. The optimum reaction conditions (reaction temperature, 40 °C; time, 20 h; methane, 20 atm; carbon monoxide, 5 atm) have been obtained. © 1998 John Wiley & Sons, Ltd.     

SB粉水热分解铝酸钠溶液制取大孔容高比表面拟薄水铝石

 以德国Condea公司用有机醇铝法生产的拟薄水铝石SB粉为晶种,采用水热分解铝酸钠溶液结合乙醇分散洗涤种分产物的方法制得了大孔容高比表面拟薄水铝石. 研究了铝酸钠溶液组成(Al2O3浓度和苛化系数)以及晶种循环使用次数等条件对溶液分解率、 Na2O析出率和种分产物孔体积、孔径分布、比表面积以及钠含量等物化性质的影响. 研究表明, 在晶种比为1.0, 温度为125 ℃的条件下用SB粉分解铝酸钠溶液(Al2O3含量为100～140 g/L, 苛化系数为1.30～1.45), 3 h后溶液分解率可达30%左右,而SB粉连续循环使用3次所得产物的孔容和比表面积分别达到0.84 cm3/g和213.6 m2/g, Na2O含量在0.3%以下,部分性质甚至超过了SB粉的技术指标. 该方法为从廉价的铝酸钠溶液制备高附加值的拟薄水铝石提供了一条新的可供选择的路径.     

Melt intercalation of polystyrene in layered silicates

We have studied the melt intercalation of polystyrene into organically modified sodium bentonite, a layered, mica-type silicate, using a variety of techniques. Wide-angle X-ray scattering experiments on polymer/silicate hybrid samples demonstrate that intercalation of polymer chains leads to an ∼25% increase in the spacing between silicate layers. The magnitude of this increase, compared with the radius of gyration of the melt polymer, implies a flattened conformation of chains in the galleries. Low voltage scanning electron microscopy reveals voids in the intercalated hybrid matrix that correspond to regions where pristine polymer was present in the physical mixture of polymer and silicate before intercalation. Differential scanning calorimetry shows that only unintercalated polymer contributes to the measured glass transition trace, so that the magnitude of the trace is diminished upon intercalation. © 1996 John Wiley & Sons, Inc.     

Organic Reactions Using Sodium Hydrogentelluride: Part 4. The Selective Reduction of Aromatic Aldehydes or Ketones with Electron-Withdrawing Groups on the Benzene Ring by Sodium Hydrogentelluride

Aromatic aldehydes or ketones which have electron-withdrawing groups on the benzene ring were selectively reduced to the corresponding alcohols in good yields by sodium hydrogentelluride; common aldehydes such as benzaldehyde and tolualdehyde were inert.     

2,6-Dimethylphenol polymerization with cuprous chloride and n-butylamine catalyst system: Effect of Nal addition

2,6-Dimethylphenol polymerization with catalyst systems based on CuCl/n-butylamine were studied under 10 kg/cm² pure oxygen pressure. By addition of sodium iodide, the catalyst performance was dramatically improved and an unusual long induction period was observed. Both the polymer intrinsic viscosity obtained and the induction period increased significantly with the increase of NaI concentration. However, the induction period decreased rapidly with the increase of n-butylamine concentration. UV-VIS absorption spectra showed that the CuCl/n-butylamine complex was converted to Cul/n-butylamine complex after the addition of NaI. The hydration rate of copper halide/n-butylamine complex decreased significantly with the increase of NaI and n-butylamine concentrations. Therefore the increase of polymer intrinsic viscosity and induction period by NaI addition suggest that the polymerization catalyst became more hydrolytically stable and less active at the higher NaI concentration. © 1996 John Wiley & Sons, Inc.     

Microparticles vs. Macroparticles as Curcumin Delivery Vehicles: Structural Studies and Cytotoxic Effect in Human Adenocarcinoma Cell Line (LoVo)

This study aimed to characterize the hydrogel micro- and macro-particles designed to deliver curcumin to human colon cancer cells (LoVo). Six series of vehicles based on sodium alginate (micro- and macro-particles, uncoated, coated with chitosan or gelatin) were synthesized. The uncoated microparticles were fabricated using an emulsion-based technique and the uncoated macroparticles with an extrusion technique, with both coupled with ionotropic gelation. The surface morphology of the particles was examined with scanning electron microscopy and the average size was measured. The encapsulation efficiency, moisture content, and swelling index were calculated. The release of curcumin from the particles was studied in an experiment simulating the conditions of the stomach, intestine, and colon. To evaluate the anticancer properties of such targeted drug delivery systems, the cytotoxicity of both curcumin-loaded and unloaded carriers to human colon cancer cells was assessed. The microparticles encapsulated much less of the payload than the macroparticles and released their content in a more prolonged manner. The unloaded carriers were not cytotoxic to LoVo cells, while the curcumin-loaded vehicles impaired their viability—more significantly after incubation with microparticles compared to macroparticles. Gelatin-coated or uncoated microparticles were the most promising carriers but their potential anticancer activity requires further thorough investigation.     

反相悬浮聚合分散剂的合成及性能

聚丙烯酸（钠）的吸水速度快,吸水量大,通常在有机介质环己烷、戊烷、（甲基）环戊烷中进行反相乳液聚合法生产,但一般只能获得颗粒细小的粉末状树脂,在介质中沉降速度慢,工程上易起粉尘危害．吸水树脂颗粒细小也影响树脂性能［１］,采用反相悬浮聚合法合成聚丙烯酸...