Dimethyl sulfoxide (DMSO) has been known for almost 150 years, but its properties as a solvent and reaction medium are far from being understood. In particular, association equilibriums in liquid DMSO have been characterized in just four papers, and the enthalpy of its self-association is unknown. The aims of this paper are to study self-association equilibriums in neat liquid DMSO at various temperatures by means of Raman spectroscopy, to find the enthalpy of self-association, and to solve the problem of hydrogen bonding in this liquid. Time correlation functions of vibrational dephasing and reorientation of coexisting monomers and dimers studied by the C-S-C and C-H symmetric vibrations indicate that external perturbations and vibrational and reorientational dynamics of these particles occur on different time scales. No signatures of H-bonding in DMSO are found. The association constants vary from 0.20 L mol(-1) (23 °C) to 0.081 L mol(-1) (100 °C). Their temperature dependence gives the enthalpy of association of DMSO as -11.7 ± 0.9 kJ mol(-1).
This work reports phase diagrams, conductivity isotherms, and data regarding the structure and dynamics of systems formed by lithium perchlorate and nitrate as solutes and sulfones as solvents. The LiClO 4 + (CH 3 ) 2 SO 2 system behaves like typical electrolytic systems containing a lithium salt and a solvent and forms a 1:1 solvate; its conductivity isotherm demonstrates a maximum. Unlike typical systems, the phase diagrams of the LiNO 3 + (CH 3 ) 2 SO 2 and LiNO 3 + (C 2 H 5 ) 2 SO 2 systems appear to be simple eutectic. The dependences of specific conductivity on the concentration of LiNO 3 are also uncommon showing no maximum characteristic to electrolyte solutions. Raman studies and analysis of dynamics performed using Raman data signify that, in the LiClO 4 + (CH 3 ) 2 SO 2 system, solvated cations and contact ion pairs exist. In the LiNO 3 + (CH 3 ) 2 SO 2 system, contact ion pairs are present as well, but signatures of cation solvation cannot be found. † Part of the "Josef M. G. Barthel Festschrift".
The creation of multi-stimuli-sensitive composite polymer–inorganic materials is a practical scientific task. The combination of photoactive magneto-piezoelectric nanomaterials and ferroelectric polymers offers new properties that can help solve environmental and energy problems. Using the doctor blade casting method with the thermally induced phase separation (TIPS) technique, we synthesized a hybrid polymer–inorganic nanocomposite porous membrane based on polyvinylidene fluoride (PVDF) and bismuth ferrite (BiFeO3/BFO). We studied the samples using transmission and scanning electron microscopy (TEM/SEM), infrared Fourier spectroscopy (FTIR), total transmission and diffuse reflection, fluorescence microscopy, photoluminescence (PL), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vibrating-sample magnetometer (VSM), and piezopotential measurements. Our results demonstrate that the addition of BFO increases the proportion of the polar phase from 76.2% to 93.8% due to surface ion–dipole interaction. We also found that the sample exhibits laser-induced fluorescence, with maxima at 475 and 665 nm depending on the presence of nanoparticles in the polymer matrix. Furthermore, our piezo-photocatalytic experiments showed that under the combined actions of ultrasonic treatment and UV–visible light irradiation, the reaction rate increased by factors of 68, 13, 4.2, and 1.6 compared to sonolysis, photolysis, piezocatalysis, and photocatalysis, respectively. This behavior is explained by the piezoelectric potential and the narrowing of the band gap of the composite due to the mechanical stress caused by ultrasound.
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