@article{kwansa_pani_deloach_tieppo_moskala_perri_yingling_2023, title={Molecular Mechanism of Plasticizer Exudation from Polyvinyl Chloride}, volume={6}, ISSN={["1520-5835"]}, url={https://doi.org/10.1021/acs.macromol.2c01735}, DOI={10.1021/acs.macromol.2c01735}, abstractNote={Plasticizers improve polymer material flexibility and durability by lowering glass transition and cold flex temperatures. While many different classes of plasticizers have been synthesized and used in various applications, several classes have been phased out due to concerns over their safety. One of the main problems that hinder the development of a new generation of efficient and safe plasticizers is the plasticizers’ migration and exudation from polymer materials, which leads to a reduction of mechanical properties and premature degradation. Here, we employed multiscale molecular dynamics, validated by experiment, to investigate the molecular mechanism of exudation of an orthophthalate plasticizer (di-2-ethylhexyl phthalate (DEHP)), non-orthophthalate plasticizers (di-n-butyl terephthalate (DnBT) and di-2-ethylhexyl terephthalate (DEHT)), and their blends from polyvinyl chloride (PVC). The results suggest that DnBT acted as an intermediary between PVC and DEHT, improving the compatibility of the plasticizer blend and reducing the degree of exudation. Specifically, it was predicted that the 70:30 wt % DnBT–DEHT blend was on par with the DEHP control system. These results also suggest that plasticizer-PVC compatibility is a stronger determinant of plasticizer exudation than the plasticizer size, diffusivity, and viscosity, given that DnBT is a smaller, more mobile, faster-diffusing, and lower-viscosity plasticizer than DEHT. Overall, our results indicate that the most important parameters that control exudation were Hansen solubility and consequently Flory–Huggins interaction parameters.}, journal={MACROMOLECULES}, author={Kwansa, Albert L. L. and Pani, Rakhee C. C. and DeLoach, Joseph A. A. and Tieppo, Arianna and Moskala, Eric J. J. and Perri, Steven T. T. and Yingling, Yaroslava G. G.}, year={2023}, month={Jun} }
 @article{pani_bond_krishnan_yingling_2013, title={Correlating fullerene diffusion with the polythiophene morphology: molecular dynamics simulations}, volume={9}, ISSN={["1744-6848"]}, url={https://publons.com/publon/11561895/}, DOI={10.1039/c3sm51906f}, abstractNote={Polymer film morphology is known to correlate with the efficient charge transport and device efficiency of the bulk heterojunction solar cell. Further improvements of the performance of organic solar cells require a better understanding of the mechanisms of diffusion and molecular rearrangement. In this paper, we used atomistic molecular dynamics simulations to provide insights into the factors affecting diffusion of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and fullerene (C60) into poly(3-hexylthiophene) (P3HT). We examined the diffusion and interactions of PCBMs in amorphous and around crystalline P3HTs at different temperatures. Simulations showed that fullerene particles tend to aggregate in amorphous P3HTs and on (100) surfaces. However, the diffusion of fullerenes on the (010) surface was mainly attributed to the preferential binding between fullerene cages and aromatic P3HT backbone which led to their directional diffusion on the thiophene backbone. The presence of the functional group in PCBM can be attributed to an increase in the diffusion coefficient by a factor of 1.5 to 2 as compared to C60. Interestingly low regioregularity of P3HTs reduced the diffusion and aggregation of PCBMs.}, number={42}, journal={SOFT MATTER}, publisher={Royal Society of Chemistry (RSC)}, author={Pani, Rakhee C. and Bond, Benjamin D. and Krishnan, Ganesh and Yingling, Yaroslava G.}, year={2013}, pages={10048–10055} }
 @article{pani_yingling_2012, title={Role of Solvent and Dendritic Architecture on the Redox Core Encapsulation}, volume={116}, ISSN={["1520-5215"]}, url={https://publons.com/publon/11561889/}, DOI={10.1021/jp304253g}, abstractNote={Dendrimers with redox cores can accept, donate, and/or store electrons and are used in nanoscale devices like artificial receptors, magnetic resonance imaging, sensors, light harvesting antennae, and electrical switches. However, the dendrimer molecular architectures can significantly alter the encapsulation of the redox core and charge transfer pathways, thereby changing the electron transfer rates. In this study, we used molecular dynamics simulations to investigate the role of solvent and peripheral groups on molecular structure and core encapsulation of iron-sulfur G2-benzyl ether dendrimers in polar and nonpolar solvent. We found that the dendrimer branches collapse in water and swell in chloroform. The presence of the long hydrophobic alkyl groups at the periphery deters the encapsulation of the core in water which may cause an increase in electron transfer rate. However, in chloroform, the dendrimer branches remain in the extended form, which leads to an increased radius of gyration. Our results suggest that peripheral alkyl chains in dendrimers cause steric hindrance, which prevents branches from back folding in chloroform solvent, but in water it reverses the trend. Overall, the presence of a hydrophobic interior and hydrophilic periphery in a dendrimer improves core encapsulation in water while hindering encapsulation in chloroform.}, number={28}, journal={JOURNAL OF PHYSICAL CHEMISTRY A}, publisher={American Chemical Society (ACS)}, author={Pani, Rakhee C. and Yingling, Yaroslava G.}, year={2012}, month={Jul}, pages={7593–7599} }
 @article{kim_pani_ha_koo_yingling_2012, title={The role of hydrogen bonding in water-mediated glucose solubility in ionic liquids}, volume={166}, ISSN={["1873-3166"]}, url={https://publons.com/wos-op/publon/11561884/}, DOI={10.1016/j.molliq.2011.11.008}, abstractNote={The restriction of low solubility of glucose in ionic liquids (IL) can be overcome by mixing an aqueous glucose solution into ILs. In this paper, the change in molecular interactions between glucoses in [Emim][TfO] system as a result of the presence of water molecules was explored using all-atoms molecular dynamics simulations. The water molecules initially located around glucose molecule are rapidly uptaken by anions and most of the water shell around glucose is replaced by anions. The presence of monodispersed water at low concentration leads to the increased mobility of the system components and higher solubility of glucose in water-mediated [Emim][TfO] than that in [Emim][TfO]. Our simulations show that water acts as a solubility enhancer which disrupts glucose–glucose interaction and enhances glucose–solvent (water and [TfO]−) interaction, resulting in higher glucose solubility. Hydrogen bonding network between glucose, water and [TfO]− molecules is a key driving force in the dissolution process of glucose in water-mediated ILs.}, journal={JOURNAL OF MOLECULAR LIQUIDS}, publisher={Elsevier BV}, author={Kim, Ho Shin and Pani, Rakhee and Ha, Sung Ho and Koo, Yoon-Mo and Yingling, Yaroslava G.}, year={2012}, month={Feb}, pages={25–30} }