A primary motivation for this study was to compare student perceptions and performance within a virtual learning environment to the traditional in-person learning experience for the General Chemistry II course taught during a 5-week summer session at Xavier University of Louisiana, a minority serving institution. The authors present quantitative and qualitative analyses including the comparison of student performance on exams during the COVID-19 remote learning experience with exam performance over a 3-year period of conventional in-person instruction. In this article, student grades, survey feedback, and learning outcomes are outlined. This study was performed to assist the faculty in improving and enriching the course content and its delivery, as they coped with the transition to a virtual learning environment imposed by the COVID-19 pandemic.

The demand for new ionic liquid (IL)-based systems to selectively sequester carbon dioxide from gas mixtures has prompted the development of individual components involving the tailored design of IL themselves or solid-supported materials that provide excellent gas permeability of the overall material as well as the ability to incorporate large amounts of ionic liquid. In this work, novel IL-encapsulated microparticles comprising a cross-linked copolymer shell of β-myrcene and styrene and a hydrophilic core of the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) are proposed as viable materials for CO₂ capture. Water-in-oil (w/o) emulsion polymerization of different mass ratios of β-myrcene to styrene (i.e. 100/0, 70/30, 50/50, 0/100) yielded IL-encapsulated microparticles, where the encapsulation efficiency of [EMIM][DCA] was dependent on the copolymer shell composition. Thermal analysis using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that both thermal stability and glass transition temperatures depend on the mass ratio of β-myrcene to styrene. Images from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microparticle shell morphology as well as measure the particle size perimeter. Particle sizes were found to be between 5 and 44 μm. CO₂ sorption experiments were conducted gravimetrically using TGA instrumentation. Interestingly, a trade-off between CO₂ absorption capacity and ionic liquid encapsulation was observed. While increasing the β-myrcene content within the microparticle shell increases the amount of encapsulated [EMIM][DCA], the observed CO₂ absorption capacity did not increase as expected due to reduced porosity compared to microparticles with higher styrene content in the microparticle shell. [EMIM][DCA] microcapsules with a 50/50 weight ratio of β-myrcene/styrene showed the best synergistic effect between spherical particle diameter (32.2 μm), pore size (0.75 μm), and high CO₂ sorption capacity of ∼0.5 mmol CO₂/g sample within a short absorption period of 20 min. Therefore, core-shell microcapsules composed of β-myrcene and styrene are envisioned as a promising material for CO₂ sequestration applications.

The structural and transport properties of an organic ionic plastic crystal (OIPC), triisobutyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1444FSI) with the addition of lithium bis(fluorosulfonyl)imide (LiFSI) have been investigated with a combined experimental and computational approach. After establishing the effect of thermal processing on structural and transport properties of P1444FSI, a consistent processing procedure was established to understand how P1444FSI properties change with increasing temperature and LiFSI concentration. Elevated rotational motions of ions on the plastic crystalline lattice coincides with and may facilitate solid-solid phase transitions in P1444FSI, while the transport of lithium cations within LiFSI-doped P1444FSI was found to be dominated by increased translational diffusivity with little change in rotational diffusivity. The trade-off between increased ion conductivity in the solid-state and decreased mechanical robustness with increasing LiFSI concentration presents an important challenge for P1444FSI-based solid-state electrolytes moving forward.

All-solid-state lithium ion batteries replace the traditional liquid electrolyte with a conductive solid polymer electrolyte. Replacing the liquid electrolyte in batteries has the potential to improve safe use of batteries without the need for hermetic sealing, extending the operating temperature range, and extending the lifetime of the battery. However, solid polymer electrolytes often have non-competitive conductivity compared to liquid electrolytes. Improving the conductivity of solid polymer electrolytes based on an understanding of structure-property relationships is not yet well understood, but it is believed to depend heavily on the localized segmental motion of polymer chains. This work attempts to describe the role of polymer segmental motion on lithium ion transport through the synthesis and characterization of phosphonium ionenes that include poly(ethylene oxide) “soft” segments. Synthetically, these segmented polymers offer an opportunity to systematically control the segmental motion of polymer chains (i.e. glass transition temperature) through control of PEO incorporation. Prepared by step-growth polymerization, these segmented phosphonium ionenes achieve molecular weights up to 40,000 g/mol. Also, the degradation and glass transition temperatures are dependent on the percent incorporation of PEO as determined by thermogravimetric analysis and differential scanning calorimetry, respectively. The ability to influence the physical properties of this unique class of polyelectrolyte provides a unique opportunity to systematically probe the impact of glass transition temperature on the ion transport properties of solid polymer electrolytes in lithium ion batteries. Our initial results from electrochemical impedance as well as the charge/discharge performance of these novel solid polymer electrolytes in coin cell battery assemblies will also be presented.

Solid polymer electrolytes offer potential improvements to lithium ion batteries that include extending their operating temperature range and improving the safe use of the batteries by inhibiting lithium dendrite formation. Because solid polymer electrolytes replace traditional liquid electrolytes as the lithium ion transport medium and also act as the electrode separator, these materials must offer good ionic conductivity along with providing good interfacial contact with the electrode material. This work presents the synthesis and characterization of polymer blends comprised poly(ethylene oxide) and phosphonium ionenes. Ionenes are a class of polycation that includes positive charges within the polymer backbone. Because the positive charge is a part of the polymer chain, the spacing and distribution of these charges have a significant impact on the properties of ionenes. This research focuses on determining the role of charge spacing and distribution of charges along the backbone of phosphonium ionenes on their ability to transport lithium ions. To accomplish this, phosphonium ionenes are blended with low molecular weight poly(ethylene oxide) (e.g. less than 3,000 g/mol) at mass ratios of 20:1, 10:1, and 5:1. The resulting blended solid polymer electrolyte membranes are evaluated for their thermal, mechanical and electrochemical properties along with their charge/discharge performance in coin cell batteries. The dependence of phosphonium ionene structure as well as the composition of SPE blends will be presented.