The copolymerization of vinyl chloride with 1-olefins. I. A new method of investigation of the kinetics of homopolymerization and copolymerization of vinyl chloride

The indirect volumetric method following the amount of monomers in the heterogeneous liquid reaction mixture in a constant volume of samples periodically withdrawn by means of gas chromatography. This new method utilizes periodic sampling of the heterogeneous reaction mixture from the reactor during the reaction and gas chromatographic determination of the unreacted monomers contained in the sample. Its suitability and reliability were verified for the suspension homopolymerization of vinyl chloride. The reproducibility of sampling and the accuracy of determination of the degree of conversion and of the initial reaction rate were investigated. The conversion curves obtained by this method are compared with those obtained by the classical gravimetric method.     

Polymer composites with radical salts of 1-methyl-3-alkylimidazolium-7,7,8,8-tetracyano-p-quinodimethane and their electric conductivity

The polymer composites were prepared by reticulate doping of polystyrene and poly(γ-methyl-L-glutamate)(PMGA) with 1-methyl-3-alkylimidazolium-7,7,8,8-tetracyano-p-quinodimethane simple salts I and complex salts II. The electric conductivity strongly depends on the chemical structure of the donor, on the stoichiometry and concentration of the radical salts, on the type of the polymer, and on the preparation conditions of the films. A high conductivity, even higher than that of pure radical salts measured in pressed pellets, was obtained in the PMGA doped films, and is most probably due to the α-helical conformation. This high order conformation of molecules forces microcrystals of charge transfer salts to grow in long hair-like shapes distributed regularly in the bulk of the polymer film.     

Targeted methods for quantitative analysis of protein glycosylation

Quantification of proteins by LC-MS/MS-MRM has become a standard method with broad projected clinical applicability. MRM quantification of protein modifications is, however, far less utilized, especially in the case of glycoproteins. This review summarizes current methods for quantitative analysis of protein glycosylation with a focus on MRM methods. We describe advantages of this quantitative approach, analytical parameters that need to be optimized to achieve reliable measurements, and point out the limitations. Differences between major classes of N- and O-glycopeptides are described and class-specific glycopeptide assays are demonstrated.     

Optical characterisation of SiOxCyHz thin films non-uniform in thickness using spectroscopic ellipsometry, spectroscopic reflectometry and spectroscopic imaging reflectometry

The combined optical method enabling us to perform the complete optical characterisation of weakly absorbing non-uniform thin films is described. This method is based on the combination of standard variable angle spectroscopic ellipsometry, standard spectroscopic reflectometry at near normal incidence and spectroscopic imaging reflectometry applied at normal incidence. The spectral dependences of the optical constants are determined using the non-imaging methods by using the dispersion model based on parametrisation of the density of electronic states. The local thickness distribution is then determined by imaging reflectometry. The method is illustrated by means of the complete optical characterisation of SiO_xC_yH_z thin films.     

Comparison of the Two-dimensional Fraunhofer and the Two-dimensional Fresnel Approximations in the Analysis of Surface Roughness by Angle Speckle Correlation

Abstract

In this paper we discuss some new theoretical results which we reached in the analysis of a random surface roughness in the framework of the two-dimensional (2D) Fresnel approximation. A comparison with 2D Fraunhofer approximation results is made. It is shown for experimentally reasonable values of the geometrical arrangement parameters of the method that the surface roughness measurement can be interpreted in the 2D Fraunhofer approximation only for surfaces with high slopes of surface irregularities. Surfaces with small slopes of irregularities require interpretation of the surface roughness measurement in the 2D Fresnel approximation. In this case, not only the standard deviation of surface height fluctuations but also the correlation length of the surface can be determined.     

New potentialities of the UNEX process using polyheterocyclic diamides

The possibilities of using 2,2′-bipyridine-6,6′-dicarboxamides in modified versions of the UNEX process were examined. The stability constants of complexes of Eu(III), Am(III), Th(IV), U(VI), and Np(V) ions with certain diamides substituted in the amide moiety or pyridine ring in acetonitrile were determined. The logarithms of the stability constants exceeded 7 for Eu(III) and reached 9 for 5f elements. The ability of the selected diamides in nitrobenzene and trifluoromethyl phenyl sulfone (FS-13) diluents to extract Am(III), Th(IV), U(VI), and Eu(III) was studied.     

On the miscibility of liquid polybutadienes

The miscibility of a new type of liquid polybutadiene and dihydroxypolybutadiene with various organic compounds was examined. The aim was to collect data which could be used in the evaluation of the role of miscibility in polyurethanes prepared from this new polymer. Qualitative tests using the cloud‐point method were made in the temperature range from laboratory conditions up to 140°C. Results were put on a common basis by the solvation equation and some characteristics derived from the electrostatic potential. Marked differences in the miscibility behavior between pure and hydroxyl‐terminated polybutadiene with hydroxyl compounds were revealed. The presence of only two hydroxyl groups in a relatively long hydrocarbon chain may thus affect properties of the molecule. Polar molecules are not, in general, miscible with polybutadienes. Polarity may be balanced and miscibility enhanced by supporting π‐electron‐interaction capabilities, H‐bond basicity, or a sufficiently long low‐polar part of a partner molecule. Other ways of improving miscibility is the nonsymmetrical placement of polar groups in the molecule structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1628–1635, 2000