Small-angle X-ray scattering as a useful supplementary technique to determine molecular masses of polyelectrolytes in solution.

Determination of molecular masses of charged polymers is often nontrivial and most methods have their drawbacks. For polyelectrolytes, a new possibility for the determination of number-average molecular masses is represented by small-angle X-ray scattering (SAXS) which allows fast determinations with a 10% accuracy. This is done by relating the mass to the position of a characteristic peak feature which arises in SAXS due to the local ordering caused by charge-repulsions between polyelectrolytes. Advantages of the technique are the simplicity of data analysis, the independency from polymer architecture, and the low sample and time consumption. The method was tested on polyelectrolytes of various structures and chemical compositions, and the results were compared with those obtained from more conventional techniques, such as asymmetric flow field-flow fractionation, gel permeation chromatography, and classical SAXS data analysis, showing that the accuracy of the suggested method is similar to that of the other techniques. © 2016 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1913-1917.

Synthesis of ß-cyclodextrin diazonium salts and electrochemical immobilization onto glassy carbon and gold surfaces.

This study shows that diazotized ß-cyclodextrin (ß-CD) can be produced, isolated, and immobilized onto glassy carbon and gold surfaces. 4-(1,2,3-Triazol-4-yl)benzenediazonium-ß-CD tetrafluoroborate (pDz-ß-CD) and 3-(1,2,3-triazol-4-yl)benzenediazonium-ß-CD tetrafluoroborate (mDz-ß-CD) were successfully prepared by Cu((I))-catalyzed azide alkyne coupling (CuAAC) of 6-monodeoxy-6-monoazido-ß-cyclodextrin (N(3)-ß-CD) and 4-ethynylaniline and 3-ethynylaniline, respectively, followed by diazotization. The products were isolated and stored successfully for several months at -18 °C. The intermediates and products were verified by Attenuated Total Reflectance Fourier Transform Infrared, Nuclear Magnetic Resonance, and Heteronuclear Single Quantum Coherence. pDz-ß-CD and mDz-ß-CD were immobilized onto glassy carbon and gold surfaces facilitated by electrochemical reduction of the diazonium group. The thus generated aryl radical reacted with the surface. The modified gold surfaces were investigated by Polarization Modulation Infrared Reflection Absorption Spectroscopy and cyclic voltammetry employing the redox probe K(3)Fe(CN)(6) to analyze the extent of blocking of the surfaces. Finally, the availability of the cavity of surface-immobilized ß-CD was shown by complexation of ferrocene followed by cyclic voltametric analysis.