The main objective of this study was to replace the traditionally used hydrolytically unstable PF 6 and BF 4 ionic solvents with new, stable ionic liquids (ILs) and to investigate the potential of ILs in formulation of the polymers based on methyl methacrylate and acrylonitrile with narrow polydispersities, high yields and molecular weights. Various ILs with four anions, namely, tris(pentafluoroethyl)trifluorophosphate, trifluoromethanesulfonate, trifluoroacetate and tetracyanoborate, were tested. The influence of the IL's characteristics on the free radical polymerization process was found to be significant. Trifluoromethanesulfonate-and trifluoroacetate-based ionic solvents provide the formation of polymers with the highest molecular weight (M r E8.8Â10 5 for polyacrylonitrile (PAN) and M w E18.9Â10 5 for polymethylmethacrylate (PMMA)) in quantitative yield (PAN, 96%; PMMA, 92%). Taking into account, the high ionic conductivity and satisfactory electrochemical stability of the tetracyanoborate-based ILs, composite films derived from PAN and B(CN) 4 ILs were prepared and their physico-chemical properties were investigated. The nature of the cation strongly influences the properties of the resulting composite films, namely, their flexibility, transparency, surface morphology and ionic conductivity (the maximum conductivity was found to be 1.0Â10 À2 S cm À1 at 25 1C).
We carried out an experimental study of the use of nonlinear crystals ZnTe, GaP, GaSe, DAST, and LiNbO 3 and semiconductors GaAs and InAs for the rectification of femtosecond optical pulses. This conversion produces broadband terahertz pulses consisting of a single period of the field oscillation. Here, we discuss features of different types of the terahertz converters, their efficiency, and spectral range.
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