Analyzing the surface properties of acrylic-based water-soluble polymers

The surface properties of newly synthesized N-methoxy isopropyl acrylamide, N-methoxy isopropyl methacrylamide, cyclo propyl acrylamide, and cyclo propyl methacrylamide polymers were investigated using inverse gas chromatography. The highest dispersive component of the surface energy value was obtained for cyclo propyl methacrylamide at 30°C. The values obtained for all polymers were decreasing with the increasing temperature. The values obtained for the acidic and the basic parameters revealed strong basic characters for the surface of N-methoxy isopropyl methacrylamide and cyclo propyl methacrylamide polymers and weak basic characters for the surface of N-methoxy isopropyl acrylamide and cyclo propyl acrylamide polymers.     

Surface Composition and Surface Energetics of Various Eucalypt Pulps

In this paper we report on our study of the surface chemical composition, surface energy and acid-base characteristics of plantation eucalypt pulps obtained using the kraft, neutral sulphite semichemical (NSSC) and cold soda processes. X-ray photoelectron spectroscopy (XPS) was used to quantify the surface coverages of extractives and lignin. Inverse gas chromatography (IGC) was used to analyse the dispersive component and the acid-base characteristics of the pulp samples. The pulp yield and the total lignin and extractives in the pulp increased in the sequences of kraft, NSSC and cold soda. The relative surface concentrations of extractives and lignin on the pulps (expressed in terms of the ratios of the pulp surface coverage to the total content of these materials in the pulp) did not increase in the same sequence. The relative surface concentrations of lignin and extractives on the kraft pulps were found to be distinctively higher than those of the NSSC and cold soda pulps. The dispersive components of the surface energy of all pulps were similar before extraction, but increased by different degrees after extraction, with that of the cold soda pulp showing the lowest degree of increase. The acid-base characteristics of the pulps were evaluated using the method of acceptor and donor constants described by Schultz and Lavielle and the method of work of adhesion described by Lundqvist and Ödberg. A comparison of these methods has been made. The acidity of all pulps was found to increase after extraction. The degree of increase in pulp acidity is negatively correlated with the surface lignin concentration on the pulps. The low relative acidity of the cold soda pulp is probably associated with its high surface lignin coverage. An experimental model was established to test this hypothesis.     

Acidity function of methanesulfonic acid solutions in DMF

The acidity function of solutions of methanesulfonic acids (MSA) in DMF and H₂O were measured by the indicator method at 25 °C in the 0–100% concentration range. A higher ionizing activity of HCl complexes with DMF as compared to that of similar MSA complexes was established. The relative ionizing activity of MSA molecules, H₅O₂ ⁺ ions, and ion pairs between MSA and DMF was determined. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 1940–1943, October, 1999.     

佛罗里达国际大学探究性酸碱滴定实验的研究与启示

化学实验课对培养和提升大学生的科研素养和综合能力至关重要。以美国佛罗里达国际大学的酸碱滴定实验为例,探讨美国化学实验课程设计理念和教学模式等方面的特点。同时针对我国高校化学实验教学现状,批判性地借鉴美国化学实验课的经验,在学术规范、实验设计、教学模式、评价机制等方面提出了改革建议。     

The reaction of 2-aminomethylphenols and their copper(II) complexes with esters of phosphorus acids

2-Alkyl- and 2-dialkylaminomethylphenols (AMP) with different hydrophobic substituents at the nitrogen atom and their copper(II) complexes (CAMP) react with the esters of phosphorus acids in aqueous solutions of ethanol in two stages: phosphorylated AMP (PAMP) are formed at the first stage and then hydrolyzed to the corresponding acids. The reactivity of AMP and PAMP significantly decreases when the hydrophobicity and steric hindrances of substituents at the nitrogen atom increase. An inverse dependence was found for CAMP. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1355–1360, August, 2000.     

Oxidative dehydrogenation of ethane over movmnw oxide catalysts

Catalysts based on mixed oxide of MoVMn are active at relatively low temperature for oxidative dehydrogenation of ethane. Incorporation of tungsten into MoVMn oxides enhances the catalytic activity. Enhancement of the activity is explained in the light of acid-base interaction accompanied with a redox mechanism of surface reoxidation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Control of the directions of oxidative transformation of methane over nickel-based catalysts by acid-base properties

Two completely different directions of the oxidative transformation of methane (OTM) were performed on nickel-based catalysts due to the different acid-base properties of those catalysts. The relatively acidic LaNiO_x and LiNiLaO_x/Al₂O₃ catalysts exhibit excellent Partial Oxidation of Methane to Syngas (POM) performance. However, the relatively basic LiNiLaO_x catalyst has a good Oxidative Coupling of Methane to C₂ Hydrocarbons (OCM) activity. The basic properties of the catalyst makes it difficult to reduce nickel and keeps it in the oxidized state. Reduced nickel is necessary for POM and oxidized nickel for the OCM reaction.     

Control of the catalytic effect of cetyltrimethylammonium bromide micelles by the addition of background electrolyte and nonionic surfactant

The variation of the microscopic properties (surface potential, micropolarity, etc.) of the interface of cetyltrimethylammonium bromide micelles upon the addition of a background electrolyte or the nonionic surfactant Triton X-100 decreases the rates of ion-molecular reactions, namely, alkaline hydrolysis of carboxylic acid esters and tetracoordinate phosphorus acid esters, and results in the shift of acid-base equilibria. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1933–1940, October, 2007.     

Solvation of complexes with strong symmetric H bonds in the methanesulfonic acid—2-pyrrolidone system

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions of methanesulfonic acid (MSA) in 2-pyrrolidone (Pyr) (0—100 % MSA) were examined at 30 °C. Depending on the ratio of components, two types of species with strong symmetric H bonds are formed: uncharged quasi-ion pairs of 1 : 1 composition and anions (AHA)^–. The solvation of quasi-ion pairs by base molecules and of the (AHA)^– anions by acid molecules was detected. The data on the influence of the hydrogen bond donor and acceptor on the IR spectra of the quasi-ion pairs and (AHA)^– anions are presented.