Charged Polymer Research Articles

Molecular Dynamics Study of Polyacrylamide and Polysaccharide-Derived Flocculants Adsorption on Mg(OH)2 Surfaces at pH 11

Brucite (Mg(OH)2) is a typical precipitate in the mining industry that adversely affects processes such as flotation and thickening. Gaining insights into the physicochemical properties of this mineral is critical for developing strategies to mitigate these challenges and improve operational efficiency. Additionally, incorporating natural-origin polymers aligns with the shift toward more sustainable mining practices. In this study, molecular dynamics simulations were employed to investigate the interaction of brucite with polysaccharides such as cellulose, guar gum, and alginate and to compare these with conventional polymers, including polyacrylamide, hydrolyzed polyacrylamide, and polyacrylic acid, under conditions of pH 11 in low-salinity water. The methodology enhanced adsorption sampling by incorporating additional temporary interactions between the polymer and the brucite surface. The results reveal that neutral polymers exhibit stronger and more stable interactions with brucite compared to charged polymers, which is consistent with the neutral nature of brucite under the studied conditions. Van der Waals forces predominantly govern the adsorption of polysaccharides, while Coulombic forces primarily drive interactions involving polyacrylamides. These findings provide valuable insights into the molecular mechanisms of polymer-brucite interactions, facilitating the development of more effective and sustainable mining additives.

Ultramicroporous Tröger's Base Framework Membranes With Ionized Sub-nanochannels for Efficient Acid/Alkali Recovery.

Membrane technology holds significant potential for the recovery of acids and alkalis from industrial wastewater systems, with ion exchange membranes (IEMs) playing a crucial role in these applications. However, conventional IEMs are limited to separating only monovalent cations or anions, presenting a significant challenge in achieving concomitant H⁺/OH⁻ permselectivity for simultaneous acid and alkali recovery. To address this issue, the charged microporous polymer framework membranes are developed, featuring rigid Tröger's Base network chains constructed through a facile sol-gel process. The intrinsic ultramicropore confinement and quaternary ammonium-charged functional groups provide ultrahigh size-sieving capability and enhanced Donnan exclusion for H⁺/OH⁻ selectivity; meanwhile, the internal protoplasmic channels of the polymer frameworks serve as highways for rapid ion transfer. The resulting membrane achieves high H⁺/Fe2⁺ and OH⁻/WO₄2⁻ selectivities of 694.4 and 181.0, respectively, for concurrent acid and alkali separation in diffusion dialysis and electrodialysis processes over extended operational periods (exceeding 1600 and 600 h, respectively), while maintaining remarkable transport rates. These results outperform most literature-reported and nearly all commercially available membranes. This study validates the novel applicability of polymer framework materials with ionized angstrom-scale channels and versatile functionalities in high-performance IEMs for acid/alkali resource recovery.

Parametric Studies of Polyacrylamide Adsorption on Calcite Using Molecular Dynamics Simulation

This study investigates the efficacy of polyacrylamide-based polymers, specifically hydrolysed polyacrylamide (HPAM), in reducing solids production within carbonate reservoirs. Building on our earlier simulation approach, molecular simulations were conducted to examine how these polymers adsorb onto calcite, the main mineral found in carbonate formations. The adsorption process was affected by several factors, including polymer molecular weight, charge density, temperature, and salinity. Generally, increased molecular weight, charge density, and temperature resulted in higher adsorption rates. The effect of salinity was more nuanced, as salt-bridging and charge-screening effects created competing influences. The simulation outcomes correspond closely with experimental results, offering valuable insights for designing and optimizing polymer-based strategies aimed at controlling solids production in carbonate reservoirs.

Mesoscale Filamentous Polyelectrolytes: Chemical Functionalization and Fluidic Structure.

The preparation and study of synthetic mesoscale structures opens opportunities to understand soft materials properties at length scales that are intermediate between that of the molecular and bulk, often referred to as the mesoscale. This paper details the preparation of mesoscale polymer filaments, prepared by flow coating and evaporative deposition from solution to yield filamentous versions of charged polymers. Using thiol-ene reactions on olefin-containing mesoscale polymer ribbons, anionic character in the form of carboxylates is introduced to the filamentous structures. The resultant mesoscale ribbons exhibit morphological changes as a function of their aqueous solution environment, based on their neutral versus anionic character, offering insights into the structure and morphology of small, multi-length scale, soft structures comprised of macromolecular materials.

On Diffusiophoresis of a Soft Particle with a Hydrophobic Inner Core: A Semianalytical Study.

The current study deals with a theoretical analysis of diffusiophoresis of a soft particle, consisting of a hydrophobic charged rigid core coated with an ion- and fluid-penetrable charged polymer layer suspending in an electrolyte medium in reaction to an applied concentration gradient. The inner core's hydrophobicity is assumed to be characterized by a surface-charge-dependent slip length parameter. Based on a weak particle charge consideration, the governing equations describing the flow phenomena are solved theoretically to deduce a semianalytic general diffusiophoretic mobility expression applied to an arbitrary Debye layer thickness. A closed-form analytic solution is also obtained, which applies to a thin Debye length and low permeable porous layer. The impact of the charge-dependent wettability of the rigid core on the particle's diffusiophoretic motion is analyzed. We found that the inner core's hydrophobicity profoundly influences the particle mobility at a thicker Debye layer with a constant surface charge density when the chemiphoresis and electrophoresis components assist each other. At a fixed ζ-potential, the effect of the hydrophobic core is substantial for a thinner Debye length. In addition, with a critical selection of core and polymer layer charges, mobility reversal is demonstrated by modulating the salt concentration and slip length parameters.

Bioinspired programmable coacervate droplets and self-assembled fibers through pH regulation of monomers.

Phase separation and phase transitions pervade the biological domain, where proteins and RNA engage in liquid-liquid phase separation (LLPS), forming liquid-like membraneless organelles. The misregulation or dysfunction of these proteins culminates in the formation of solid aggregates via a liquid-to-solid transition, leading to pathogenic conditions. To decipher the underlying mechanisms, synthetic LLPS has been examined through complex coacervate formation from charged polymers. Nonetheless, temporal control over phase transitions from prebiotically relevant small organic synthons remains largely unexplored. Herein, we propose utilizing pH modulation to regulate the charge of small molecular building blocks, thereby controlling the LLPS process. Through a bio-inspired, enzyme-mediated pH-regulated reaction, we introduce temporal control over both LLPS and the transition from coacervates to supramolecular polymers. Additionally, by incorporating antagonistic pH modulators, we achieve transient LLPS and further temporal regulation of supramolecular polymer disassembly. Our investigation into pH-regulated LLPS provides a new avenue for exploring the stimuli-responsive, dynamic, and transient nature of LLPS.

Review on molecular designing of polymeric carriers use in gene therapy for diabetes

Gene therapy holds promise for treating diabetes by addressing its root causes at the molecular level. A key factor in its success is the development of effective delivery systems, with polymeric carriers emerging as versatile vehicles. This review highlights the molecular design of polymeric carriers for diabetes gene therapy, focusing on critical parameters like polymer structure, size, charge, and surface modification that influence gene encapsulation and release. Biodegradable polymers such as PLGA, chitosan, and PEI are emphasized for their ability to protect therapeutic genes and enable controlled release. In diabetes, these carriers aim to deliver genes that modulate insulin production, enhance β-cell regeneration, or prevent immune-mediated destruction. The review also explores stimulus-responsive polymers that offer on-demand release based on glucose levels. Recent preclinical and clinical studies are discussed, addressing challenges and strategies for optimizing polymeric carriers. These molecular design insights could pave the way for safer, more efficient gene delivery systems in diabetes treatment. This abstract emphasizes the design principles, challenges, and emerging strategies in polymeric carrier systems for gene therapy in diabetes.

Hour-Long Afterglow in Flexible Polymeric Materials through the Introduction of Electron Donor/Acceptor Exciplexes.

The development of organic afterglow materials has garnered significant attention due to their diverse applications in smart devices, optoelectronics, and bioimaging. However, polymeric afterglow materials often suffer from short emission lifetimes, typically ranging from milliseconds to seconds, posing a significant challenge for achieving hour-long afterglow (HLA) polymers. This study presents the successful fabrication of transparent HLA polymers by introducing electron donor/acceptor exciplexes. Employing aromatic polyesters as the polymer electron acceptor and charge reservoirs, the resulting HLA polymers exhibited a remarkable green afterglow that persisted for 12 hours under ambient conditions, representing the longest duration achieved for polymeric afterglow materials to date. Intriguingly, these HLA polymers could be activated solely by sunlight, maintaining a green afterglow for over 6 hours at room temperature in air, which outperformed all previously reported afterglow polymers. The doped polymers exhibited superior flexibility and transparency, making them ideal candidates for flexible display applications. Furthermore, successfully spinning these doped polymers into fibers while retaining their HLA properties opens up exciting possibilities for their use in wearable smart devices.

Mechanisms for removing phosphorus species through sequential coagulation using inorganic coagulants and organic polymers

ABSTRACT The need for stringent phosphorus removal from domestic wastewater is increasing to mitigate eutrophication, while efficient phosphate reuse is critical due to the global phosphate crisis. Combining aluminum sulfate (ALS) with high molecular weight organic polymers achieved 95–99% removal of particles, turbidity, and phosphates, reducing ALS usage by 40%. We propose mechanisms to explain the enhanced treatment efficiency. Particle and turbidity removal is more influenced by polymer charge density than molecular weight, while orthophosphate (OP) removal is linked to a change in zeta potential from negative to positive, allowing additional OP binding through complex formation with hydrolysis products and polymers. Enhanced phospholipid (PL) removal likely results from adsorption and neutralization of micelle PL charges by intermediate positively charged aluminum hydroxyphosphate ions. Higher PL removal with low ALS doses is attributed to a two-stage dosing process that optimizes coagulant and polymer dosages. The combined removal of OP and PL improves phosphorus bioavailability, increasing the sludge's fertilizer value.

Solvation-free energy of uncharged and charged water-soluble synthetic polymer using adaptive Poisson-Boltzmann solver: poly(acrylic acid)

ABSTRACT Implicit solvent based on the Poisson-Boltzmann model of electrostatics provides a faster approach to the calculation of solvation and conformations of polymers compared to explicit solvents in molecular dynamics simulations. While PB-based methods have been used extensively for biological macromolecules, here we present the use of the Adaptive Poisson-Boltzmann Solver (APBS) approach for the solvation of synthetic polymer in water. Stereo-specific (isotactic) poly(acrylic acid) of different chain lengths (20–55 for uncharged and 15–50 for charged) are sampled from atomistic molecular dynamic simulations in explicit water followed by APBS in implicit water. The hydration energy of uncharged and charged polymers varies linearly with the number of units (N). The variation of total solvation energy for SASA (Solvent Accessible Surface Area) and SAV (Solvent Accessible Volume) shows a crossover from one scaling to the other. While such a transition is known for small hydrophobic solutes, we report this for a dilute solution of polymer at uncharged and fully charged conditions and in implicit solvent.

Influence of Solvent Dielectric Constant on the Complex Coacervation Phase Behavior of Polymerized Ionic Liquids.

Complex coacervation is an associative phase separation process of oppositely charged polyelectrolyte solutions, resulting in a coacervate phase enriched with charged polymers and a polymer-lean phase. To date, studies on the phase behavior of complex coacervation have been largely restricted to aqueous systems with relatively high dielectric constants due to the limited solubility of most polyelectrolytes, hindering the exploration of the effects of electrostatic interactions from differences in solvent permittivity. Herein, we prepare two symmetric but oppositely charged polymerized ionic liquids (PILs), consisting of poly[1-[2-acryloyloxyethyl]-3-butylimidazolium bis(trifluoromethane)sulfonimide] (PAT) and poly[1-ethyl-3-methylimidazolium 3-[[[(trifluoromethyl)sulfonyl]amino]sulfonyl]propyl acrylate] (PEA). Due to the delocalized ionic charges and their chemical structure similarity, both PAT and PEA are soluble in various organic solvents with a wide range of dielectric constants, ranging from 16.7 (hexafluoro-2-propanol (HFIP)) to 66.1 (propylene carbonate (PC)). Notably, no significant correlation is observed between the solvent dielectric constant and the phase diagram of the complex coacervation of PILs. Most organic solvents lead to similar phase diagrams and salt resistances regardless of their dielectric constants, except two protic solvents (HFIP and 2,2,2-trifluoroethanol (TFE)) showing significantly low salt resistances compared to the others. The low salt resistance in these protic solvents primarily arises from strong hydrogen bonding between PILs and solvents as evidenced by 1H NMR and small-angle neutron scattering (SANS) experiments. Our finding suggests that for the coacervation of PILs, particularly those with delocalized and weak charge interactions, entropy from the counterion release and polymer-solvent interaction χ parameter play a more important role than the electrostatic interactions of charged molecules, rendered by the dielectric constant of the solvent medium.

Injectable Self-Healing and Anti-Dissolving Low-Molecular-Weight Hydrogels Enabled by Ionic Cross-Linking for Cell Encapsulation.

Injectable behavior is often observed in polymer-based hydrogels yet is rarely achieved in low-molecular-weight hydrogels (LMWHs), the realization of which may boost the development of new soft materials for biomedical applications. Here, we report on injectable self-healing and antidissolving LMWHs that are formed through a simple ionic cross-linking strategy, showing a fundamental application for the encapsulation of living cells. The LMWHs are formed by simply mixing Ca2+ with negatively charged supramolecular polymers. Surprisingly, the resultant hydrogels are capable of rapidly self-healing within seconds after damage, showing an unexpected injectable function. When the hydrogel is injected into an aqueous medium, continuous macroscopic hydrogel fibers can be produced. Interestingly, the hydrogel can remain intact in the aqueous medium, showing impressive antidissolving behavior which is less observed in other LMWHs. Furthermore, the hydrogel is demonstrated to be nontoxic and can be used as a cytocompatible scaffold for living cells. This work may open an avenue toward injectable and antidissolving LMWHs for the ever-expanding list of applications in biotherapy and bioprinting.

Versican controlled by Lmx1b regulates hyaluronate density and hydration for semicircular canal morphogenesis.

During inner ear semicircular canal morphogenesis in zebrafish, patterned canal-genesis zones express genes for extracellular matrix component synthesis. These include hyaluronan and the hyaluronan-binding chondroitin sulfate proteoglycan Versican, which are abundant in the matrices of many developing organs. Charged hyaluronate polymers play a key role in canal morphogenesis through osmotic swelling. However, the developmental factor(s) that pattern the synthesis of the matrix components and regulation of hyaluronate density and swelling are unknown. Here, we identify the transcription factor, Lmx1b, as a positive transcriptional regulator of hyaluronan, Versican, and chondroitin synthesis genes crucial for canal morphogenesis. We show that Versican regulates hyaluronan density through its protein core, whereas the charged chondroitin side chains contribute to the hydration of hyaluronate-ECM. Versican-tuned properties of hyaluronate matrices may be a broadly used mechanism in morphogenesis with important implications for understanding diseases where these matrices are impaired, and for hydrogel engineering for tissue regeneration.

Insights into the Synthesis of a Semiconducting Nickel Bis(dithiolene) Coordination Polymer.

Nickel bis(dithiolene) complexes are promising candidates for novel n-type semiconductors, which are air-stable and highly conductive. A key issue for further development is that their synthesis often yields undesired products, greatly limiting the degree of polymerization as well as purity and adversely affecting their electronic properties. Crucially, there is a lack of in-depth identification of these species and understanding of the reaction mechanism. This study explores the mechanism of a reaction forming the coordination polymer nickel-thieno[3,2-b]thiophenetetrathiolate (Ni-TT). We find that the Unoxidized Ni-TT intermediate contains negatively charged polymer chains with Ni2+ counter cations. Oxidation in the final synthetic step occurs primarily at the ligand, resulting in a more neutral Ni-TT. Our investigation also reveals that the ligand can form dimeric and trimeric species via disulfide bonds as byproducts. These insights are pivotal knowledge to develop metal bis(dithiolene)-based coordination polymers to achieve purity and quality required for electronic applications.

Characteristics of Ketapang Leaf Extract and PVA Nano Fibers Using the Electrospinning Method

The electrospinning method is a method of making nanofibers using the influence of an electric field to produce a jet of electrically charged polymer solution. In this experiment, polyvinyl alcohol (PVA) nanofibers and ketapang leaf extract with various viscosities were made using electrospinning equipment with a static collector. Scanning using an electron microscope (SEM) shows that the morphology of the nanofibers formed looks homogeneous, continuous, and without beads (beads free). The SEM results were analyzed using ImageJ software, which was then carried out using Origin software to determine the fiber diameter. Diameter size distribution with fiber diameter size distribution ranging from 2000 to 8000 nm.

Translation as a Biosignature.

Life on Earth relies on mechanisms to store heritable information and translate this information into cellular machinery required for biological activity. In all known life, storage, regulation, and translation are provided by DNA, RNA, and ribosomes. Life beyond Earth, even if ancestrally or chemically distinct from life as we know it, may utilize similar structures: it has been proposed that charged linear polymers analogous to nucleic acids may be responsible for storage and regulation of genetic information in nonterran biochemical systems. We further propose that a ribosome-like structure may also exist in such a system, due to the evolutionary advantages of separating heritability from cellular machinery. In this study, we use a solid-state nanopore to detect DNA, RNA, and ribosomes, and we demonstrate that machine learning can distinguish between biomolecule samples and accurately classify new data. This work is intended to serve as a proof of principal that such biosignatures (i.e., informational polymers or translation apparatuses) could be detected, for example, as part of future missions targeting extant life on Ocean Worlds. A negative detection does not imply the absence of life; however, the detection of ribosome-like structures could provide a robust and sensitive method to seek extant life in combination with other methods. Key Words: RNA world-Darwinian evolution-Nucleic acids-Agnostic life detection. Astrobiology xx, xxx-xxx.

Custom-built charged covalent-organic polymer for elevated-temperature boosted separation cum selective and benign fixation of CO2 with bi-phasic iodine scavenging

Custom-built charged covalent-organic polymer for elevated-temperature boosted separation cum selective and benign fixation of CO2 with bi-phasic iodine scavenging

Numerical simulation of shock initiation characteristics of fusion detonators

Abstract To provide an economic and safe destruction program, this paper is based on the jet detonation method of poly energy charge structure design. The use of simulation software is to establish the diameter of the 40 mm polymer charge physical model, and the combat structure model is used for the invasion and detonation simulation calculations. The results show that the theoretical calculations and simulations are in good agreement and the structure can penetrate the 40 mm thick 50SiMnVB shell, to observe the shock wave in the shielding cover and shielding explosives between the transmission process, finding that the thickness of the shell affects the impact detonation mechanism.

Novel cationic and amphoteric starch-modified coagulants for efficient treatment of relatively high turbidity and large organic matter source waters: Performance, predictive modeling and mechanism analysis

Finding alternative solutions of water source containing short-term relative high turbidity and large organic content is a pressing need in view of the inherent limitations of traditional inorganic coagulants. Requirement of significant dosage increase for conventional iron and aluminum salt coagulants can create several challenges including dose adjustment, suboptimal performance and high concentration of residual metal ions. In this study, acrylamide monomer (AM) and methacryloyloxyethyltrimethylammonium chloride (DMC) were grafted onto starch and carboxymethyl starch to obtain novel cationic and amphoteric starch-modified coagulants. Concurrently, the obtained coagulants were comprehensively evaluated under varying simulated water quality conditions to analyze their turbidity and organic matter removal efficiencies. Polymerized aluminium chloride (PACl) was used as the reference coagulant to evaluate the roles of polymer charge density, total charge, and molecular chain length in the coagulation mechanism for further illustration of their efficacy. In comparison to the traditional coagulant PACl, the modified coagulant was found to be more effective in enhancing flocculation and aggregation behavior, lowering of energy barriers, and enhancing adsorption energy by using the Density Functional Theory (DFT) calculations and Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory based investigation of the mechanism. Moreover, these behaviors were mainly attributed to significant exchange of charge density between coagulant and the pollutants. Additionally, in order to facilitate accurate and efficient treatment of water having diverse qualities, quadratic polynomial equation based mathematical model was constructed for quantitative analysis and model prediction. Findings of this study point towards an effective and precise approach to coagulation technology and thereby enabling sustainable and efficient purification of turbid source water containing large organic matter.

Half-integer topological defects paired via string micelles in polar liquids.

Ferroelectric nematic (NF) liquid crystals present a compelling platform for exploring topological defects in polar fields, while their structural properties can be significantly altered by ionic doping. In this study, we demonstrate that doping the ferroelectric nematic material RM734 with cationic polymers enables the formation of polymeric micelles that connect pairs of half-integer topological defects. Polarizing optical microscopy reveals that these string defects exhibit butterfly textures, featured with a 2D polarization field divided by Néel-type kink walls into domains exhibiting either uniform polarization or negative splay and bend deformations. Through analysis of electrophoretic motion and direct measurements of polarization divergences, we show that the string micelles are positively charged, and their side regions exhibit positive bound charges. To elucidate these observations, we propose a charge double-layer model for the string defects: the positively charged cationic polymer chains and densely packed RM734 molecules form a Stern charge layer, while small anionic ions and positive bound charges constitute the charge diffusion layer. Notably, our experiments indicate that only cationic polymer doping effectively induces the formation of these unique string defects. These findings enhance our understanding of ionic doping effects and provide valuable insights for engineering polar topologies in liquid crystal systems.