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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.

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.