Polydimethylsiloxane Elastomers Filled with Rod-Like α-MnO2 Nanoparticles: An Interplay of Structure and Electrorheological Performance

For the first time, electroactive nanocomposite elastomers based on polydimethylsiloxane and filled with rod-like α-MnO2 nanoparticles have been obtained. The curing of the filled elastomer in an electric field, resulting in the ordering of the α-MnO2 particles, had a significant effect on the degree of polymer crosslinking, as well as on the electrorheological characteristics of the nanocomposites obtained through this process, namely the values of the storage and loss moduli. The dielectric spectra of filled elastomers in the frequency range 25–106 Hz were analysed in terms of interfacial relaxation processes. It has been shown, for the first time, that the application of an electric field leads to a decrease in the value of the Payne effect in composite elastomers. Analysis of the rheological effect in the obtained materials has demonstrated the possibility of designing highly efficient electrorheological elastomers that change their elastic properties by 4.3 times in electric fields of up to 2 kV/mm.

The Essential Role of 1-Butyl-3-Methylimidazolium-Based Ionic Liquids in the Development of Transparent Silica-Filled Elastomer Systems

In this paper, we present the design of reinforced silica-filled elastomer composites exhibiting a high transparency, high mechanical performance in static and dynamic conditions, and improved electrical conductivity. Two different imidazolium ionic liquids (ILs) were used with increasing loads: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIMTFSI) and 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIMAlCl4). The composites were prepared in a two-roll mill. The influence of the ILs on the dispersion of the silica in the nitrile rubber (NBR) matrix was assessed by scanning electron microscopy (SEM). The presence of ILs in the NBR/SiO2 systems improved the crosslink density and ionic conductivity of the composites. Their mechanical properties and aging stability remained almost unchanged, at a very satisfactory level. Greater crosslinking was observed for the NBR/SiO2 composites containing BMIMAlCl4, due to its catalytic effect on the efficiency of interface crosslinking reactions. We found the optimal formulation for obtaining transparent reinforced NBR/SiO2 composites. The application of 2.5 phr of BMIMAlCl4 resulted in a high transparency in the case of NBR composites filled with 30 phr of silica.