We use simulations and experiments to delineate the mechanism by which the addition of a small number of polar −OH groups to a nonpolar polymer increases the static relative permittivity (or dielectric constant) by a factor of 2, but more importantly while keeping the dielectric loss in the frequency regime of interest to power electronics to less than 1%. Dielectric properties obtained from experiments on functionalized polyethylenes and polypropylenes as a function of −OH doping are in quantitative agreement with one another. Molecular dynamics simulations for the static relative permittivity of “dry” −OH functionalized polyethylene (in the absence of water) are apparently in quantitative agreement with experiments. However, these simulation results would further imply that there should be considerable dielectric loss beyond simulation time scales (>0.1 μs). Since there are minimal experimentally observed dielectric losses for times as short as a microsecond, we believe that a small amount of adsorbed water plays a critical role in this attenuated loss. We use simulations to derive the water concentration at saturation, and our results for this quantity are also in good agreement with experiments. Simulations of the static relative permittivity of PE–OH incorporating this quantity of hydration water are found to be in quantitative agreement with experiments when it is assumed that all the dipolar relaxations occur at time scales faster than 0.1 μs. These results suggest that improved polymeric dielectric materials can be designed by including −OH groups on the chain, but the mechanism requires the presence of a stoichiometric quantity of hydration water.

In this work, a joint experimental and computational study on the synthesis, self-assembly, and ionic conduction characteristics of a new conjugated liquid crystal quaterthiophene/poly(ethylene oxide) (PEO4) consisting of terminal tetraethyleneglycol monomethyl ether groups on both ends of a quaterthiophene core is performed. In agreement with molecular dynamic simulations, temperature-dependent grazing-incidence wide angle X-ray scattering and X-ray diffraction indicate that the molecule spontaneously forms a smectic phase at ambient temperature as characterized both in bulk and thin film configurations. Significantly, this smectic phase is maintained upon blending with bis(trifluoro-methanesulfonyl)imide as ion source at a concentration ratio up to r = [Li + ]/[EO] = 0.05. Nanosegregation between oligothiophene and PEO moieties and π-π stacking of thiophene rings lead to the formation of efficient 2D pathways for ion transport, resulting in thin-film in-plane ionic conductivity as high as 5.2 × 10 −4 S cm −1 at 70 °C and r = 0.05 as measured by electrochemical impedance spectroscopy. Upon heating the samples above a transition temperature around 95 °C, an isotropic phase forms associated with a pronounced drop in ionic conductivity. Upon cooling, partial and local reordering of the conducting smectic domains leads to an ionic conductivity decrease compared to the as-cast state.the crystalline phase, but they are easier to align homogeneously and spontaneously over large areas. [3] Ordered self-assembled molecules can induce enhanced properties and functions, [4] thus enabling specific applications in a wide variety of advanced technologies. [5,6] The idea of using LCs for ion [7][8][9][10] and electron [5,6,11,12] transport has attracted much attention in recent decades. The spontaneous phase segregation between immiscible parts [5,6,[13][14][15] enables the use of LCs as anisotropic ion conductors, making them promising candidates for energy devices. Moreover, their properties of fast assembly and easy processability [16] excel those of traditional electrolytes. By tuning the molecular shape and intermolecular interactions, mesogenic molecules can self-assemble into a range of LC nanostructures such as columnar, smectic, or bicontinuous cubic phases, providing 1D, [17][18][19] 2D, [20][21][22][23][24] and 3D [7,[25][26][27][28] ion transport pathways. These molecules have been proposed for potential application as efficient and stable electrolytes for batteries and dye-sensitized solar cells. [10,[29][30][31][32][33] 1D and 2D channels formed by discotic and rod-like LCs, respectively, are mostly studied.In general, ion-conducting LCs consist of polar or ionic groups such as cyclic carbonates, [10,[32][33][34] poly(ethylene oxide) s (PEOs), [20,21,35,36] or cationic and anionic moieties attached to rod-like or wedge-shaped moieties to achieve columnar

T-shaped bolaamphiphiles (TBA) with a swallow-tail lateral chain have been found to provide a fertile platform to produce complex liquid crystalline phases that are accessible through changes of temperature and lateral chain length and design. In this work, we use molecular simulations of a simple coarse-grained model to map out the phase behavior of this type of molecules. This model is based on the premise that the crucial details of the fluid structure stem from close range repulsions and the strong directional forces typical of hydrogen bonds. Our simulations confirm that TBAs exhibit a rich phase behavior upon increasing the length of their lateral chain. The simulations detect a double gyroid phase and an axial-bundle columnar phase which bear some structural resemblance to those found in the experiment. In addition, simulations predict two cocontinuous phases with 3D-periodicity: the "single" diamond and the "single" plumber's nightmare phase. Our analysis of energetic and entropic contributions to the free energy of phases formed by TBA with either swallow-tail or linear side-chains suggest that the 3D-periodic network phases formed by the former are stabilized by the large conformation entropy of the side-chains.