@article{park_rahmani_treasure_lee_tiller_pasquinelli_kelley_park_2024, title={Understanding the formation of insoluble gel particles during cellulose diacetate production}, volume={2}, ISSN={["1572-882X"]}, url={http://dx.doi.org/10.1007/s10570-024-05769-0}, DOI={10.1007/s10570-024-05769-0}, journal={CELLULOSE}, author={Park, Seonghyun and Rahmani, Farzin and Treasure, Trevor and Lee, Joo and Tiller, Phoenix and Pasquinelli, Melissa A. and Kelley, Stephen S. and Park, Sunkyu}, year={2024}, month={Feb} }
 @article{rahmani_pasquinelli_2022, title={Molecular Insights into the Interfacial Properties of Cellulose Surfaces with Varying Types of Ionic Liquid Epoxies}, volume={4}, ISSN={["2637-6105"]}, url={https://doi.org/10.1021/acsapm.2c00243}, DOI={10.1021/acsapm.2c00243}, abstractNote={Due to the excellent physio-chemical and mechanical properties, ionic liquid epoxies (ILE) can serve as a perfect material for various technologies along with many other materials as a substrate. In this study, we employed molecular dynamics simulations to gain fundamental molecular insights about a conventional epoxy and an imidazolium-based ILE and how adhesion on crystalline cellulose surfaces is affected by cross-linking and the type of ionic liquid (IL) counter anions (e.g. [OAc], [Cl], and [TF2N]) on thermo-mechanical and moisture absorption of bulk ILE were further investigated. When comparing the ILE/cellulose systems versus bulk ILE systems, the results indicate that the presence of a cellulose surface lowers the degree of cross-linking due to the adsorption of the hardener on its surface. Overall, the ILEs/cellulose exhibit a higher interfacial bonding energy than conventional epoxy/cellulose. Improved adhesion is significant for hydrophilic ILEs, which is likely attributed to hydrogen bonds formed between the cellulose and anion molecules. This computational study provides molecular-level insights into the adsorption mechanism of ILE onto a crystalline cellulose surface, leading to the design of smart and multifunctional thermoset adhesives.}, number={5}, journal={ACS APPLIED POLYMER MATERIALS}, publisher={American Chemical Society (ACS)}, author={Rahmani, Farzin and Pasquinelli, Melissa A.}, year={2022}, month={May}, pages={3734–3742} }
 @article{guha_rahmani_berkowitz_pasquinelli_grace_2022, title={Temporal evolution of the behavior of absorbed moisture in a damaged polymer-quartz composite: A molecular dynamics study}, volume={214}, ISSN={["1879-0801"]}, DOI={10.1016/j.commatsci.2022.111690}, abstractNote={• Interfacial Debonding was simulated on a nanoscale using an atomistic model of a quartz-fiber composite. • The temporal behavior of absorbed moisture was analyzed near the damage site. • Irrespective of the initial state of moisture in the composite, they eventually agglomerate near the damage location. • Spatial confinement near the interface bolsters previous experiments which hypothesize that absorbed moisture behaves like bulk water when clustered at microcracks. Exposure of a composite structure to mechanical or environmental stressors often leads to the formation of damage sites which contain rupture mechanisms such as matrix cracking and interfacial debonding. Continued accumulation of this type of small-scale damage can cause sudden and catastrophic large-scale failure. A novel damage characterization technique which leverages the altered physical and chemical states of naturally absorbed moisture in response to sub-micron scale damage has recently shown promise for early detection of damage. In this work, molecular dynamics simulations are used to better understand the differences in the behavior of absorbed water molecules near a damage site. The results show that, irrespective of the initial distribution of molecular water throughout the composite, or the presence of polar atoms in the polymer matrix, water tends to preferentially cluster near the damage location. It was also found that spatial confinement near the polymer-fiber interface hinders diffusion of the water molecules into the polymer matrix. These molecular level insights bolster the hypothesis formulated in previous experimental studies that absorbed moisture behaves like free water in terms of its dielectric activity when the water molecules agglomerate at the damage location. Consequently, this locally distinct permittivity can be leveraged for damage detection and quantification.}, journal={COMPUTATIONAL MATERIALS SCIENCE}, author={Guha, Rishabh D. and Rahmani, Farzin and Berkowitz, Katherine and Pasquinelli, Melissa and Grace, Landon R.}, year={2022}, month={Nov} }
 @article{banerjee_dedmon_rahmani_pasquinelli_ford_2021, title={Cyclization kinetics of gel-spun polyacrylonitrile/aldaric-acid sugars using the isoconversional approach}, volume={10}, ISSN={["1097-4628"]}, url={https://doi.org/10.1002/app.51781}, DOI={10.1002/app.51781}, abstractNote={AbstractComonomers, such as methacrylic acid, itaconic acid, and acrylic acid, can minimize the activation energy of polyacrylonitrile (PAN) cyclization through their nucleophilic reaction with pendant nitrile groups. An understanding of how these comonomers affect the kinetics of PAN cyclization inspired this study on how the isomeric sugars (glucaric acid(cis) and mucic acid(trans)) would influence PAN cyclization. Until now, researchers have characterized the cyclization of PAN by single activation energy; however, this approach using differential scanning calorimetry does not represent the conversion dependent kinetics of cyclization. The isoconversional method was used to evaluate exotherms for cyclization at three different heating rates while allowing the calculation of activation energy at incremental increases in conversion (α). The aldaric acid sugars reduced the activation energy of initiation by ~five times in comparison to values observed for neat PAN fiber and the ratio of (k1/k2) (where k1 is the rate constant for initiation and k2 is the rate constant for propagation) improved by ~2 orders of magnitude. Based on molecular dynamic simulations, hydrogen bonding between the aldaric acids sugars and PAN lowered the activation energy at the onset of cyclization.}, number={11}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, publisher={Wiley}, author={Banerjee, Debjyoti and Dedmon, Hannah and Rahmani, Farzin and Pasquinelli, Melissa and Ford, Ericka}, year={2021}, month={Oct} }
 @article{rahmani_scovazzo_pasquinelli_nouranian_2021, title={Effects of Ionic Liquid Nanoconfinement on the CO2/CH4 Separation in Poly(vinylidene fluoride)/1-Ethyl-3-methylimidazolium Thiocyanate Membranes}, volume={13}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.1c13169}, DOI={10.1021/acsami.1c13169}, abstractNote={A combined experimental and molecular dynamics (MD) simulation approach was used to investigate the effects of the nanoconfinement of a highly CO2/CH4-selective ionic liquid (IL), 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), in porous poly(vinylidene fluoride) (PVDF) matrices on the gas separation performance of the resulting membranes. The observed experimental CO2/CH4 permselectivity increased by about 46% when the nominal pore diameter in PVDF, which is a measure of nanoconfinement, decreased from 450 to 100 nm, thus demonstrating nanoconfinement improvements of gas separation. MD simulations corroborated these experimental observations and indicated a suppression in the sorption of CH4 by [EMIM][SCN] when the IL nanoconfinement length decreased within the nonpolar PVDF surfaces. This is consistent with the experimental observation that the CH4 permeance through the IL confined in nonpolar PVDF is significantly less than the CH4 permeance through the IL confined in a water-wetting polar formulation of PVDF. The potential of mean force calculations further indicated that CO2 has more affinity to the nonpolar PVDF surface than CH4. Also, a charge/density distribution analysis of the IL in the PVDF-confined region revealed a layering of the IL into [EMIM]- and [SCN]-rich regions, where CH4 was preferentially distributed in the former and CO2 in the latter. These molecular insights into the nanoconfinement-driven mechanisms in polymer/IL membranes provide a framework for a better molecular design of such membranes for critical gas separation and CO2 capture applications.}, number={37}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Rahmani, Farzin and Scovazzo, Paul and Pasquinelli, Melissa A. and Nouranian, Sasan}, year={2021}, month={Sep}, pages={44460–44469} }
 @article{zhang_jeon_rahmani_nouranian_jiang_2022, title={Sintered Ti/Al core/shell nanoparticles: computational investigation of the effects of core volume fraction, heating rate, and room-temperature relaxation on tensile properties}, volume={55}, ISSN={["1361-6463"]}, DOI={10.1088/1361-6463/ac2ad7}, abstractNote={Molecular dynamics simulations were performed to roughly imitate the conditions of selective laser sintering during additive manufacturing. The role of core volume fraction on the resultant uniaxial tensile properties of sintered Ti/Al bimetallic core/shell nanoparticles (NPs) was investigated during various sintering states. A chain model was created from five single thermally equilibrated Ti/Al NPs with weak neck connections by a solid-state sintering process at room temperature (298 K). The chains were heated to 800 K with two heating rates (0.04 and 0.2 K ps−1), underwent high-temperature relaxation, and were cooled to 298 K with a cooling rate of 0.08 K ps−1. They were then relaxed at 298 K for different periods (i.e. 1, 4, and 10 ns). In a follow-up procedure, those sintered NPs were subjected to uniaxial tension at different strain rates (i.e. 0.001, 0.01, and 0.1% ps−1). The thermodynamic properties and the structural evolutions of atomic configurations were investigated during the sintering process. The tensile responses were also obtained to examine the final product quality. The results indicate a strong correlation between the tensile strength of the final sintered chain product and the Ti core volume fraction. A larger Ti core volume fraction yields a stronger chain structure, resulting in higher tensile strength. The effect of heating rate on the tensile strength of final products with larger core volume fraction is more pronounced. The effect of room-temperature relaxation is not obvious on the tensile strength except for two products, which were sintered with the fast heating rate and tested under the lowest/highest strain rate. Also, high strain rates improve the tensile strength, and low strain rates will lead to enhanced ductility of the final products, especially with residual single atomic chain.}, number={2}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Zhang, Huadian and Jeon, Jungmin and Rahmani, Farzin and Nouranian, Sasan and Jiang, Shan}, year={2022}, month={Jan} }
 @article{kareem_rahmani_hyman_keller_pasquinelli_savin_grayson_2021, title={Solution size variation of linear and dendritic bis-MPA analogs using DOSY-H-1 NMR}, volume={12}, ISSN={["1759-9962"]}, url={https://doi.org/10.1039/D0PY01070G}, DOI={10.1039/d0py01070g}, abstractNote={The size and size variability of bis-MPA dendrimers is shown to be smaller by DOSY-1H NMR than their linear analog, PBBM. This was accomplished using five different solvents and for the first time confirms, experimentally, what has been theorized.}, number={10}, journal={POLYMER CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Kareem, Oluwapelumi O. and Rahmani, Farzin and Hyman, Jason A. and Keller, Christopher B. and Pasquinelli, Melissa A. and Savin, Daniel A. and Grayson, Scott M.}, year={2021}, month={Mar}, pages={1507–1517} }
 @article{nouranian_asiaee_rahmani_jiang_lopez_fiske_edmunson_fox_kaukler_alkhateb_2021, title={Solvation of potential stable cations and anions originating from the Martian regolith in select ionic liquids}, volume={324}, ISSN={["1873-3166"]}, DOI={10.1016/j.molliq.2020.114691}, abstractNote={Element recovery from the Martian regolith using ionic liquids (ILs) is an active area of research within the field of in-situ resource utilization. In this work, we performed a classical molecular dynamics (MD) simulation study to better understand the solvation thermodynamics and structures of potential cationic and anionic species originating from the Martian regolith in two select ILs, i.e., 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) and 1-ethyl-3-methylimidazolium hydrogen sulfate ([emim][HSO4]), at two temperatures of 298.15 and 473.15 K. The studied cationic and anionic species represent the stable ions, i.e., a series of tetra-, tri-, di-, and monovalent cations, as well as several silicate, phosphate, chromate, titanate, and select halide anions, based on the mineral composition of the Martian regolith. We calculated the solvation free energies (SFEs) of these ionic species in the ILs using the free energy perturbation method. Moreover, we investigated the solvation environment of these ionic solutes by generating the relevant radial distribution functions and calculating the running coordination numbers of ILs' anions and cations surrounding the solutes. Overall, the average absolute values of the SFEs for cationic solutes increase with increasing ion valency (charge) and size of the solute at both temperatures. For anionic solutes, a more complex effect of anion molecular size and charge is responsible for the trends observed in the absolute values of the SFEs. For example, we found orthosilicate to be the most soluble anionic species in both ILs. On the other hand, the dichromate anion was found to be essentially insoluble in both ILs. Comparing between the solvation efficiencies of the ILs, [emim][Ac] shows larger negative SFE values than [emim][HSO4] for all cationic solutes at both temperatures. While the temperature effect on the solvation of cationic solutes is mixed, higher temperatures generally favor the dissolution of the anionic solutes in both ILs. Our results provide molecular insights into the solvation thermodynamics of various potential ionic species that may be extracted from the Martian regolith using suitable ILs.}, journal={JOURNAL OF MOLECULAR LIQUIDS}, author={Nouranian, Sasan and Asiaee, Alireza and Rahmani, Farzin and Jiang, Shan and Lopez, Alexander M. and Fiske, Michael R. and Edmunson, Jennifer E. and Fox, Eric T. and Kaukler, William F. and Alkhateb, Hunain}, year={2021}, month={Feb} }