Publications by authors named "Z Wojnarowska"

A group of new zwitterion based ionic liquid crystals (ILCs) have been synthesized. Depending on the counter anion (mesylate or hydrogen sulfate) the phase behavior of the resulting ILCs is quite different. Mesylate based ILCs show complex phase behavior with multiple phases depending on the alkyl chain length.

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Article Synopsis
  • This study investigates how the length of alkyl chains in alkyltriethylammonium-based ionic liquids affects both dynamic heterogeneity and dynamic behavior during transitions.
  • The researchers used techniques like differential scanning calorimetry and broadband dielectric spectroscopy to show that these ionic liquids are great at forming glass and have good ionic conductivity at room temperature.
  • Results indicate that as the alkyl chain length increases, the number of correlated molecules at the glass transition decreases and the temperature where complex dynamics begin also rises.
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The fundamental Debye-Stokes-Einstein (DSE) relation between rotational relaxation times and shear viscosity attracts longstanding research interest as one of the most important characteristics of many glass-forming liquids. Here, we provide strong evidence, missing so far, for the relevance of anisotropy for DSE-related behavior. Dielectric spectroscopy and shear viscosity measurements were employed to get insight into the decoupling between reorientation relaxation times and viscosity for anisotropic glass-formers with dipole moments oriented parallel or perpendicular to the long molecular axis.

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A range of protic ionic liquids (PILs) based on tri-n-alkylammonium cations and mesylate/triflate anions were incorporated into a polymer matrix to form ionogels (IGs). These systems were investigated for their thermal and electrochemical behaviour, as well as under the aspect of ion motion via PFG-NMR. The ionic conductivities of the ILs/IGs are in the range of 10-10 S/cm at elevated temperatures and the diffusion coefficients are around 10 m s.

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The effects of alkyl chain length on the crystallization kinetics and ion mobility of tetraalkylphosphonium, [P][TFSI], ( = 2, 6, 8, and 12) ionic liquids were studied by differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) over a wide temperature range. The liquid-glass transition temperature () and ion dynamics examined over a broad range were almost insensitive to structural modifications of the phosphonium cation. In contrast, the crystallization kinetics were strongly affected by the length of the fourth alkyl chain.

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