We perform extensive molecular dynamics simulations of a highly charged, collapsed, flexible polyelectrolyte chain in a poor solvent for the case when the electrostatic interactions, characterized by the reduced Bjerrum length l, are strong. We find the existence of several sub-regimes in the dependence of the gyration radius of the chain R on l characterized by R ∼ l. In contrast to a good solvent, the exponent γ for a poor solvent crucially depends on the size and valency of the counterions. To explain the different sub-regimes, we generalize the existing counterion fluctuation theory by including a more complete account of all possible volume interactions in the free energy of the polyelectrolyte chain. We also show that the presence of condensed counterions modifies the effective attraction among the chain monomers and modulates the sign of the second virial coefficient under poor solvent conditions.
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http://dx.doi.org/10.1039/c6sm02152b | DOI Listing |
Angew Chem Int Ed Engl
January 2025
South China Normal University, Chemistry, 55 W Zhongshan Rd, 510006, Guangzhou, CHINA.
Lithium-sulfur (Li-S) batteries has been regarded as one of the most promising next-generation energy storage systems due to their high theoretical energy density. However, the practical application of Li-S batteries is still hindered by the unstable cathode-electrolyte interphase and the early passivation of charge product (Li2S), leading to poor cycling stability and low S utilization. Herein, we propose an electrolyte engineering strategy using highly solvating hexamethylphosphoramide (HMPA) as a co-solvent to elucidate the dissociation-precipitation chemistry of lithium polysulfides (LiPSs).
View Article and Find Full Text PDFChem Sci
January 2025
School of Materials and Energy, University of Electronic Science and Technology of China Chengdu 611731 China
Silicon (Si) is considered a promising anode material for next-generation lithium-ion batteries due to its high theoretical specific capacity and earth-abundancy. However, challenges such as significant volume expansion, unstable solid electrolyte interphase (SEI) formation in incompatible electrolytes, and slow lithium-ion transport lead to its poor cycling and rate performance. In this work, it is demonstrated that superior cyclability and rate capability of Si anodes can be achieved using ethyl fluoroacetate (EFA) and fluoroethylene carbonate (FEC) solvents with low binding energy with Li but with sufficiently high relative dielectric constants.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK.
CO capture is an important process for mitigating CO emissions in the atmosphere. Recently, ionic liquids have been identified as possible systems for CO capture processes. Major drawbacks of such systems are mostly in the high cost of synthesis of such liquids and poor biodegradability.
View Article and Find Full Text PDFCurr Org Synth
January 2025
Laboratoire de Chimie Organique (LR17ES08), Faculté des Sciences de Sfax, University of Sfax, Route de Soukra Km 3.5, BP 1171, 3000, Sfax, Tunisia.
Aim And Objective: It is well established that 4H-pyran derivatives hold a significant position in synthetic organic chemistry due to their diverse biological and pharmacological properties. This work aims to introduce a novel synthetic pathway for highly functionalized 4H-pyran derivatives, achieved through a 1,4-Michael addition followed by a cascade cyclization. This reaction is catalyzed by LiOH·H2O under ultrasonic irradiation in water, offering an efficient and environmentally friendly approach.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Block copolymers (BCPs) can form nanoparticles having different morphologies that can be used as photonic nanocrystals and are a platform for drug delivery, sensors, and catalysis. In particular, BCP nanoparticles having disk-like shape have been recently discovered. Such nanodisks can be used as the next-generation antitumor drug delivery carriers; however, the applicability of the existing nanodisks is limited due to their poor or unknown ability to respond to external stimuli.
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