Dynamic Mixing Behaviors of Ionically Tethered Polymer Canopy of Nanoscale Hybrid Materials in Fluids of Varying Physical and Chemical Properties

Abstract

An emerging area of sustainable energy and environmental research is focused on the development of novel electrolytes that can increase the solubility of target species and improve subsequent reaction performance. Electrolytes with chemical and structural tunability have allowed for significant advancements in flow batteries and CO2 conversion integrated with CO2 capture. Liquid-like nanoparticle organic hybrid materials (NOHMs) are nanoscale fluids that are composed of inorganic nanocores and an ionically tethered polymeric canopy. NOHMs have been shown to exhibit enhanced conductivity making them promising for electrolyte applications, though they are often challenged by high viscosity in the neat state. In this study, a series of binary mixtures of NOHM-I-HPE with five different secondary fluids, water, chloroform, toluene, acetonitrile, and ethyl acetate, were prepared to reduce the fluid viscosity and investigate the effects of secondary fluid properties (e.g., hydrogen bonding ability, polarity, and molar volume) on their transport behaviors, including viscosity and diffusivity. Our results revealed that the molecular ratio of secondary fluid to the ether groups of Jeffamine M2070 (λSF) was able to describe the effect that secondary fluid has on transport properties. Our findings also suggest that in solution, the Jeffamine M2070 molecules exist in different nanoscale environments, where some are more strongly associated with the nanoparticle surface than others, and the conformation of the polymer canopy was dependent on the secondary fluid. This understanding of the polymer conformation in NOHMs can allow for the better design of an electrolyte capable of capturing and releasing small gaseous or ionic species.

Insights into the Enhanced Oxidative Thermal Stability of Nanoparticle Organic Hybrid Materials Developed for Carbon Capture and Energy Storage

“…Because the stability of NOHM-I-HPE remained relatively unchanged in the presence or absence of oxygen (see Figure and Table ), the enhanced oxidative thermal stability of the ionically tethered polymer compared to untethered HPE is proposed to result from a mass transfer resistance to oxygen. Overall, these results are in good agreement with previously reported data, which show that the thermal stability of NOHM-I-HPE was significantly higher than that of HPE, in the presence of an oxygen-containing atmosphere. ,, …”

“…The NMR T 1 relaxation time measures the longitudinal relaxation of an excited nucleus and depends upon the local and global surroundings. Throughout the literature, the T 1 relaxation time has been used to assess polymer mobility in various environments, where grafted polymers have been shown to possess shorter relaxation times than untethered polymers as a result of steric confinement. ,− …”

“…Our previous studies have shown that the introduction of the nanoparticle in ionic NOHMs leads to an increase in the viscosity of NOHM-based fluids compared to the corresponding HPE-based fluids ,, and empirical correlations have been developed to model the viscosity of HPE- and NOHM-based fluids . These previously determined empirical relationships were used to estimate the viscosity and self-diffusion coefficients of neat HPE and NOHM-I-HPE in the range of 25–600 °C, and the results are displayed in Figure S1 of the Supporting Information.…”

“…NOHM-I-HPE was synthesized using previously described methods, and a representative structure is shown in Figure . ,,,,,, A total of 18.3 g of a 30 wt % colloidal suspension of 7 nm diameter SiO 2 nanoparticles (LUDOX SM-30 obtained from Sigma-Aldrich) was diluted to a concentration of 4 wt % in deionized water. A total of 30 g of a 35 wt % 3-(trihydroxysilyl)-1-propane-sulfonic acid solution (Gelest, Inc.) was further diluted to a final concentration of 7 wt %.…”

“…The grafting density of polymer chains in NOHM-I-HPE was estimated to be around 2.5 chains/nm 2 based on the results from the thermogravimetric decomposition curves (see Figure ) and the range of SiO 2 surface area provided by the manufacturer. The maximum grafting density for polymers of similar molecular weight (i.e., 2000 g/mol) is generally limited to less than 1.5 chains/nm 2 . ,, Our recent studies have shown that there are different types of polymers, including tethered and interacting polymers, that are strongly associated with the nanoparticle cores. , Thus, the estimated polymer grafting density includes both types of polymers.…”