Controlling Nanoparticle Location In Block Copolymers Using External Fields: Experiments And Simulations

Advances in materials synthesis and fabrication techniques allow an unprecedented control over the creation of novel building blocks such as polymers and particles. The first principle for effective utilization of these building blocks is to create techniques to control their assembly at length scales ranging from nanoscale to macroscopic scale. Hierarchically structured materials have been fabricated by combining the functionalities of block copolymer nanocomposites with the advantages of nanofibers. First, a novel methodology to synthesize block copolymer nanofibers with ordered self assembly has been developed, followed by a systematic study on how this self assembly is altered due to the cylindrical confinement of nanofibers. Then, this self assembly in nanofibers is used as a template to control the spatial distribution of functional nanoparticles. One of the key findings of this work is that a much larger fraction of nanoparticles can be placed (without agglomeration) within nanofibers compared to films of the same materials. To zero in on the mechanism and to understand the thermodynamic and kinetic processes that drive nanoparticle placement in block copolymers during deformation (an important constituent of electrospinning nanofiber fabrication process), coarse grained molecular dynamics simulations have been conducted. Here, the effect of shear flow on different types of block copolymer/nanoparticle systems has been first studied, followed by a study on effect of elongational flow on various block copolymer nanocomposite systems

Dielectric constants and refractive indices of 1-propanol or 2-propanol + cyclohexane, benzene, toluene, <i>o-, m- </i>and <i>p</i>-xylene at 308.15 K

974-978Dielectric constants and refractive indices data at 308.15 K for 1-propanol or 2-propanol with cyclohexane, benzene, toluene, o-, m- and p-xylene have been reported. The analysis of data shows the presence of strong specific interactions between propanol and aromatic hydrocarbon. Frohlich equation is used to calculate the apparent dipole moment of these binary mixtures

Molar excess volumes of 1-propanol or 2-propanol + cyclohexane or aromatic hydrocarbons at 303.15 K

508-512Molar excess volume data for 1-propanol or 2-propanol + cyclohexane or benzene or toluene or o- or m-or p-xylen at 303.15 K have been reported. VE data for these binary systems are also interpreted in terms of Mecke-Kempter type association model with a Flory contribution term. The predicted VEvalues, to some extent, are in good agreement with the experimental data

Molar excess free energy of mixing of 1-propanol or 2-propanol + aromatic hydrocarbons at 308.15 K in terms of an association model with a Flory contribution term

219-229<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">Excess molar Gibbs free energy of mixing for 1-propanol or 2-propanol + benzene, + toluene, + o-, m-and pxylenes at 308.15 K are calculated by Barker's method from vapour pressure data measured by a static method. The free energy of mixing for these binary systems are also predicted in terms of Mecke-Kempter type of association model with Flory contribution term using two interaction parameters. The predicted value agrees reasonably well with the experimental values.</span

Polysulfide Speciation and Electrolyte Interactions in Lithium–Sulfur Batteries with <i>in Situ</i> Infrared Spectroelectrochemistry

Understanding redox mechanisms as well as interactions between redox species and electrolyte is critical for rational design of electrolyte/cathode systems for Li–S batteries. Here, we demonstrate <i>in situ</i> FT-IR with attenuated total reflection (ATR) to monitor both polysulfide (PS) speciation (S_<i>x</i>^2–, 2 ≤ <i>x</i> ≤ 8) and triflate anion (electrolyte) coordination state while simultaneously discharging/charging a full battery coin cell. We report the concentration of various PS species as a function of voltage during cell discharge. In addition, we found that molecular-level changes occurred in the electrolyte salt anion in response to PS speciation. During discharge, PS dissolution increases total solute concentration, inducing anion interactions between low coordination state complexesion pairs and free ionsto form aggregate complexes. Under fast cyclic voltammetry sweep, less progressive formation of all PSs, due to diffusion limitations, resulted in a higher concentration of aggregates and PSs even upon completion of discharge. This new application of <i>in situ</i> FT-IR offers direct insight into dynamic interactions between electrolyte salt and polysulfides fundamental in developing Li–S systems