Hydrophobic Association Research Articles

Tailoring Waterborne Coating Rheology with Hydrophobically Modified Ethoxylated Urethanes (HEURs): Molecular Architecture Insights Supported by CG-MD Simulations.

A novel investigation of the effects of the hydrophilic and hydrophobic segments of hydrophobically modified ethoxylated urethanes (HEURs) on the rheological properties of their aqueous solutions, latex-based emulsions, and waterborne paints is demonstrated. Different HEUR thickeners were produced by varying the poly(ethylene glycol) (PEG) molecular weight and terminal hydrophobic size. Results reveal that the strength of hydrophobic associations and, consequently, the rheological properties of HEUR formulations can be effectively controlled by modifying the structure of the hydrophobic segment, specifically, the combination of diisocyanate and monoalcohol. This allows for the on-demand attainment of diverse rheological behaviors ranging from predominantly Newtonian profiles exhibiting lower viscosities to markedly pseudoplastic behaviors with significantly higher viscosities. The length of the hydrophilic group appears to affect viscosity only marginally up to a molecular weight of 23,000 g/mol, with more notable effects at 33,000 g/mol. Additionally, it was indicated that the rheological responses observed in water solutions provide a reliable forecast of their behavior in latex-based emulsions and waterborne paints. Coarse-grained molecular dynamics (CG-MD) simulations were also applied to gain insight into HEUR micelle dynamics in aqueous solutions. Guided by the DBSCAN algorithm, the simulations successfully captured the concentration-dependent behavior and the impact of hydrophilic chain length, aligning with the experimental viscosity trends. Various metrics were employed to provide a comprehensive analysis of the micellization process, including the hydrophobic cluster volume, the total micellar volume, the aggregation number, and the number of chains interconnecting with other micelles.

Distinguish MnO2/Mn2+ Conversion/ Zn2+ Intercalation/ H+ Conversion Chemistries at Different Potentials in Aqueous Zn||MnO2 Batteries

AbstractThe rechargeable aqueous Zn||MnO2 chemistry has been extensively explored, but its electrochemical reaction mechanisms, especially in the context of MnO2/Mn2+ conversion and Zn2+/H+ intercalation chemistry, remain not fully understood. Here, we designed an amphiphilic hydrogel electrolyte, which distinguished the MnO2/Mn2+ conversion, Zn2+ intercalation, and H+ intercalation and conversion processes at three distinct discharge plateaus of an aqueous Zn||MnO2 battery. The amphiphilic hydrogel electrolyte is featured with an extended electrochemical stability window up to 3.0 V, high ionic conductivity, Zn2+‐selective ion tunnels, and hydrophobic associations with cathode materials. This specifically designed electrolyte allows the MnO2/Mn2+ conversion reaction at a discharge plateau of 1.75 V. More interesting, the discharge plateaus of ~1.33 V, previously assigned as the co‐intercalation of Zn2+ and H+ ions in the MnO2 cathode, are specified as the exclusive intercalation of Zn2+ ions, leading to an ultra‐flat voltage plateau. Furthermore, with a distinct three‐step electrochemical energy storage process, a high areal capacity of 1.8 mAh cm−2 and high specific energy of 0.858 Wh cm−2, even at a low MnO2 loading mass of 0.5 mg cm−2 are achieved. To our knowledge, this is the first report to fully distinguish different mechanisms at different potentials in aqueous Zn||MnO2 batteries.

Distinguish MnO2/Mn2+ Conversion/ Zn2+ Intercalation/ H+ Conversion Chemistries at Different Potentials in Aqueous Zn||MnO2 Batteries.

The rechargeable aqueous Zn||MnO2 chemistry has been extensively explored, but its electrochemical reaction mechanisms, especially in the context of MnO2/Mn2+ conversion and Zn2+/H+ intercalation chemistry, remain not fully understood. Here, we designed an amphiphilic hydrogel electrolyte, which distinguished the MnO2/Mn2+ conversion, Zn2+ intercalation, and H+ intercalation and conversion processes at three distinct discharge plateaus of an aqueous Zn||MnO2 battery. The amphiphilic hydrogel electrolyte is featured with an extended electrochemical stability window up to 3.0 V, high ionic conductivity, Zn2+-selective ion tunnels, and hydrophobic associations with cathode materials. This specifically designed electrolyte allows the MnO2/Mn2+ conversion reaction at a discharge plateau of 1.75 V. More interesting, the discharge plateaus of ~1.33 V, previously assigned as the co-intercalation of Zn2+ and H+ ions in the MnO2 cathode, are specified as the exclusive intercalation of Zn2+ ions, leading to an ultra-flat voltage plateau. Furthermore, with a distinct three-step electrochemical energy storage process, a high areal capacity of 1.8 mAh cm-2 and high specific energy of 0.858 Wh cm-2, even at a low MnO2 loading mass of 0.5 mg cm-2 are achieved. To our knowledge, this is the first report to fully distinguish different mechanisms at different potentials in aqueous Zn||MnO2 batteries.

Ta-Fe in-situ coating PES membrane and its application in oily wastewater treatment: Insight into modification and anti-fouling mechanisms

Membrane fouling is a serious problem that limits the widespread application of membrane technology. Herein, we propose an effective modification method by in-situ modifying polyethersulfone (PES) ultrafiltration membrane with tannic acid (TA) and Fe3+ chelates to improve its pollution resistance. The TA-Fe3+ complexes could deposit on the PES membrane surface and form a hydration layer by Van Der Waals force, hydrogen bonding force, and hydrophobic association. The modified membrane (PES\\TA\\Fe3+) had enhanced fouling resistance and membrane flux due to its dual advantages of abundant OH groups and favorable spatial structure. After modification, the roughness of membrane surface increased from 219 nm to 257 nm, and its water contact angle decreased from 58.9° to 26.5°, endowing the PES\\TA\\Fe3+ membrane with a strong resistance to oil droplets through electrostatic repulsion, steric hindrance effect, and hydrogen bonding force. Polyaluminum chloride-polydimethyldiallylammonium chloride (PAC-PDMDAAC) could alleviate 85 % membrane fouling resistance. PAC-PDMDAAC mainly mitigated irreversible membrane fouling by removing oil droplets and forming large and loose flocs. While the use of PES\\TA\\Fe3+ membrane mainly reduced the adsorption resistance and the resistance of membrane itself. The anti-fouling performance of PES\\TA\\Fe3+ membrane changed with pH owing to the changes in the properties of TA-Fe3+ complexes. The hydrophilic layer would be decomposed under alkaline conditions due to the deprotonation of TA and excessive hydrolysis of Fe3+. This study provides an efficient anti-fouling strategy and reveals the modification and anti-fouling mechanisms of the hydrophilic membrane, providing theoretical guidance for the further development of membrane technology.

Enhancing Oil Recovery in Low-Permeability Reservoirs Using a Low-Molecular Weight Amphiphilic Polymer.

Polymer flooding has achieved considerable success in medium-high permeability reservoirs. However, when it comes to low-permeability reservoirs, polymer flooding suffers from poor injectivity due to the large molecular size of the commonly used high-molecular-weight (high-MW) partially hydrolyzed polyacrylamides (HPAM). Herein, an amphiphilic polymer (LMWAP) with a low MW (3.9 × 106 g/mol) was synthesized by introducing an amphiphilic monomer (Allyl-OP-10) and a chain transfer agent into the polymerization reaction. Despite the low MW, LMWAP exhibited better thickening capability in brine than its counterparts HPAM-1800 (MW = 1.8 × 107 g/mol) and HPAM-800 (MW = 8 × 106 g/mol) due to the intermolecular hydrophobic association. LMWAP also exhibited more significant shear-thinning behavior and stronger elasticity than the two counterparts. Furthermore, LMWAP possesses favorable oil-water interfacial activity due to its amphiphilicity. The oil-water interfacial tension (IFT) could be reduced to 0.88 mN/m and oil-in-water (O/W) emulsions could be formed under the effect of LMWAP. In addition, the reversible hydrophobic association endows the molecular chains of LMWAP with dynamic association-disassociation transition ability. Therefore, despite the similar hydrodynamic sizes in brine, LMWAP exhibited favorable injectivity under low-permeability conditions, while the counterpart HPAM-1800 led to fatal plugging. Furthermore, LMWAP could enhance oil recovery up to 21.5%, while the counterpart HPAM-800 could only enhance oil recovery by up to 11.5%, which could be attributed to the favorable interfacial activity of LMWAP.

Protection of bovine serum albumin through encapsulation in hybrid vesicles

This study focuses on hybrid vesicles (HVs) formed through co-assembly of soy phosphatidylcholine (SPC) and a triblock copolymer (F127). After elucidating the superior stability of HVs over the assemblies of neat SPC and F127, these were encapsulated with bovine serum albumin (BSA), as model a thermolabile protein. Characterizations were performed using dynamic light scattering (DLS), electron microscopy, circular dichroism and high-sensitivity differential scanning calorimetry. The size of HVs increased slightly at higher proportion of F127 and upon encapsulation of BSA. In spite of this, vesicles remained spherical and displayed a smooth surface. They showed superior dilution stability in comparison to neat copolymer micelles and phospholipid vesicles. Their stability can be ascribed to hydrophobic association between the phospholipid and copolymer, and manifested into increase in phase transition temperature of the former. We found that HVs could protect BSA from denaturation and unfolding when challenged by high solution temperature, pH changes and salt incorporation.

Study of a high salt tolerant amphiphilic polymer and its salt thickening mechanism

Polymer flooding is the most reliable method for the petroleum industry to further enhance oil recovery from the developed oil field and to keep the total oil production. For the reservoirs with high salinity, traditional polymer fluids, for example partially hydrolyzed polyacrylamide (HPAM), are failed to improve oil recovery rate due to the molecular agglomeration caused by compression-diffusion electric double layer. By optimizing the copolymerization of cyclic structure monomer n-vinylpyrrolidone (NVP) and long-chain hydrophobic monomer cetyl dimethyl allyl ammonium chloride (C16DMAAC), a high salt tolerant amphiphilic polymer P(AM/NVP/C16DMAAC), abbreviated as PANC, is synthesized. The optimal polymerization conditions were determined depending on the apparent viscosity measured by the rheometer. The microstructure of the polymer was evaluated using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and scanning electron microscopy. The viscosity of 2000 mg/L PANC increased to 42.7 mPa·s at the salinity of 11.6 × 104 mg/L and temperature of 40 °C, while the viscosity of HPAM was only 7.3 mPa·s under the same condition. The viscosity of PANC was 479 % higher than that of HPAM, indicating the remarkable salt tolerant property of PANC. The viscosity of PANC increased from 12 mPa·s to 42.7 mPa·s when the salinity increased from 1 × 104 mg/L to 11.6 × 104 mg/L. By comparing the salt resistance of polymer PANC and polymer P(AM/AA/C16), abbreviated as AP-C16, indicating that NVP enhanced the rigidity of the PANC molecular chain, and hindered the shrinkage and curling of the molecular chain after salt addition. The inclusion effect of β-cyclodextrin on the hydrophobic groups of PANC indicated that PANC increased viscosity through the hydrophobic association of C16DMAAC. Furthermore, PANC showed a salt thickening ability due to the synergy effect of C16DMAAC and NVP. As such, the salt tolerant amphiphilic polymer PANC offers a novel polymer flooding material for oil displacement, especially under a high-salinity condition.

Rheological behavior of hydrophobic association polyacrylamides with high salt resistance and corrosion inhibition: Cross-linking modification based on trace dopamine hydrochloride derivatives

Hydrophobic association polyacrylamides (HAPAMs) have great potential for use in polymer flooding because of their unique aggregative, hygroscopic, and other compatible properties; however, their poor solubility in high-salt reservoir environments is one of the drawbacks of current polymers for enhanced oil recovery (EOR) applications. Herein, an amphipathic hydrophobic monomer (hexadecyldimethylallyl ammonium chloride, DMAAC16) and a dopamine hydrochloride-derived monomer (DAAM) were successfully introduced into HAPAM to synthesize novel dopamine hydrochloride-modified hydrophobic association polymers (HAPAMC16D). As a result, HAPAMC16D exhibited not only good comprehensive properties based on its porous network structure but also excellent viscosity due to the presence of the DAAM monomer. When the concentration of the polymer solution was greater than the critical association concentration (CAC), the apparent viscosity reached 614 mPa s at 5 g/L C16D5. Importantly, the salt resistance increased significantly in the representative sodium and calcium ion tests, which was attributed to the degree of chemical cross-linking and the intermolecular hydrophobic bonding force. The temperature and salt resistance tests simulating different environments for EOR showed that C16D4 had an apparent viscosity of 158 mPa s, a retention rate of 28.52 % at 90 °C and a total dissolved solids (TDS) greater than 30,000. Additionally, the weight loss method and electrochemical experiments indicated that the highly salt-resistant hydrophobic association polymers had favorable corrosion inhibition effects, with an inhibition efficiency of up to 99.02 % in the 1 M hydrochloric acid-Q235 carbon steel system. This hydrophobic association strategy provides a new approach for designing highly salt-resistant materials for polymer flooding in harsh reservoir environments.

Double physical network hydrogels with rapid self-recovery and multistimuli-responsive shape memory effects based on low-methoxyl pectin and host-guest interactions

Double physical network (DPN) hydrogels exhibit superior performance compared with other hydrogel types due to their unique crosslinking structure. However, certain mechanical properties, such as self-recovery and fatigue resistance, still need improvement, and stimuli-responsiveness can be expanded for a wider range of applications. In this study, we presented a facile strategy for designing multifunctional DPN hydrogels based on a poly-cyclodextrin (PCD) and adamantane (Ad) host-guest supramolecular crosslinked polyacrylamide (PAAm) network and a low-methoxyl pectin (LMP) network established through Ca2+ or H+. ‘Egg box’ junction zones between Ca2+ and COO− on the LMP chains, as well as hydrogen bonding and hydrophobic association junction zones, could be formed during this process. The synergistic effect of the flexible supramolecular network and the stiff LMP network imparted remarkable stress tolerance, fatigue resistance, ductility, and anti-piercing capacities to the DPN hydrogels. The thermal reversible DPN structure also endowed the hydrogel with thermal-accelerated rapid self-recovery, as the hydrogel can virtually recover to its original state within 40 min at 80 °C. Multistimuli-responsive including chemical- and thermal-induced shape memory behavior was achieved based on the versatile LMP network. The temporary shape of the LMP hydrogel could be fixed with the introduction of Ca2+ or H+, while spontaneous shape recovery was observed under near infrared (NIR) radiation or immersion in K2CO3 or NaOH solutions, respectively. Additionally, the DPN hydrogels exhibited notable self-healing behavior when the cut surfaces were contacted and stored at 80 °C. More importantly, green natural resources derived raw materials of cyclodextrin (CD) and LMP also offered a sustainable strategy to prepare functional hydrogels. The combination of the above features of the LMP DPN hydrogel provided a new method for designing smart materials with ideal functions for soft actuators and biomedical applications.

Two-Level Self-Thickening Mechanism of a Novel Acid Thickener with a Hydrophobic-Associated Structure during High-Temperature Acidification Processes.

Two acid thickeners, ADMC and ADOM, were prepared by aqueous solution polymerization using acrylamide (AM) and methacryloyloxyethyl trimethyl ammonium chloride (DMC) as raw materials, with or without the introduction of octadecyl polyoxyethylene ether methacrylate (OEMA). It was characterized by FTIR, 1H NMR, and the fluorescence spectra of pyrene. The double-layer thickening mechanism of ADOM was proved by comparing the thickening and rheological properties of ADMC and ADOM tested by a six-speed rotary viscometer and a HAKKE MARSIV rheometer during the acidification process. The results showed that the synthetic product was the target product; the first stage of the self-thickening ADOM fresh acid solution during high-temperature acidification was mainly affected by Ca2+ concentration, and the second stage of self-thickening was mainly affected by temperature. The residual viscosity of the 0.8 wt% ADOM residual acid solution was 250, 201.5, and 61.3 mPa·s, respectively, after shearing at 90, 120, and 150 °C for 60 min at a shear rate of 170 s-1. The thickening acid ADOM with a hydrophobic association structure has good temperature resistance and shear resistance, which can be used for high-temperature deep-well acid fracturing. In addition, no metal crosslinking agent was introduced in the system to avoid damage to its formation, and ADOM exhibited good resistance to Ca2+, which could provide ideas for the reinjection of the acidizing flowback fluid. It also has certain advantages for environmental protection.

Bioinspired stormwater control measure for the enhanced removal of truly dissolved polycyclic aromatic hydrocarbons and heavy metals from urban runoff

Stormwater harvesting (SWH) addresses the UN's Sustainable Development Goals (SDGs). Conventional stormwater control measures (SCMs) effectively remove particulate and colloidal contaminants from urban runoff; however, they fail to retain dissolved contaminants, particularly substances of concern like polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs), thereby hindering the SWH applicability. Here, inspired by protein folding in nature, we reported a novel biomimetic SCM for the efficient removal of dissolved PAHs and HMs from urban runoff. Lab-scale tests were conducted together with a more mechanistic investigation on how the contaminants were removed. By integrating hydrophobic organic chains with low-cost hydrophilic flocculant matrixes, our biomimetic flocculants achieved a 1.4–9.5 times removal of all detected dissolved PAHs and HMs, while enhancing the removal of a wide-spectrum of particulate and colloidal contaminants, compared to existing SCMs. Ecotoxicity, as indicated by newborn Daphnia magna as experimental organisms, was reduced from “acute toxicity” of the original runoff sample (toxic unit of ∼2.6) to “non-toxicity” (toxic unit < 0.4) of the treated water. The improved performance is attributed to the protein-folding-like features of the bioinspired flocculants providing: (i) stronger binding to PAHs (via hydrophobic association) and HMs (via coordination), and (ii) the ability of spontaneous aggregation. The bio-inspired approach in this work holds strong promise as an alternative or supplementary component in SCM systems, and is expected to contribute to sustainable water management practices in relation to SDGs.

Ionic organohydrogel with long-term environmental stability and multifunctionality based on PAM and sodium alginate

Hydrogels possess several advantageous characteristics, including transparency, biocompatibility, and ionic conductivity, making them promising for applications in flexible electronics, drug delivery, ionic skin, and electrolytes. Nevertheless, creating a robust conductive and antifreezing hydrogel with enduring environmental stability remains a significant challenge. This study, based on the salt-out effect of alkali metal ion salts and binary solvent systems, employs a straightforward one-pot solvent exchange method to introduce dynamic and reversible non-covalent bonds (hydrophobic association and hydrogen bonds) into a polyacrylamide-sodium alginate (PAM-SA) dual-network hydrogel with excellent flexibility and biocompatibility. By adjusting the types of ions and cryoprotective agents (CPA), a series of ion-conductive organic hydrogels with anti-freezing properties were successfully prepared. The resulting PAM/SA-Gly-KCl1M hydrogel exhibits commendable mechanical properties (with a tensile strain of up to 1465 %, a tensile strength of 166 kPa, and toughness of 1354 kJ m3), high ionic conductivity (0.59 S/m), outstanding frost resistance (–100 °C), and sustained long-term stability (maintaining 70 % of its weight for over one month in an open environment). Therefore, sensors based on organic hydrogels exhibit exceptional characteristics, including high strength, superior transparency, and dependable operation in low-temperature conditions. Its remarkable sensing sensitivity and stability and antifreeze properties facilitate operation across an extensive temperature range and contribute to an extended operational lifespan. Overall, this sensor proves conducive to developing enduring flexible electronic products in challenging environments, thereby unveiling novel prospects for the realms of smart wearable technology and health monitoring.

Highly Resilient Noncovalently Associated Hydrogel Adhesives for Wound Sealing Patch.

The development of hydrogel adhesives with high mechanical resilience and toughness remains a challenging task. Hydrogels must exhibit high mechanical resilience to withstand the inevitable movement of the human body while simultaneously demonstrating strong wet tissue adhesion and appropriate toughness to hold and seal damaged tissues; However, tissue adhesion, toughness, and mechanical resilience are typically negatively correlated. Therefore, this paper proposes a highly resilient double-network (DN) hydrogel wound-sealing patch that exhibits a well-balanced combination of tissue adhesion, toughness, and mechanical resilience. The DN structure is formed by introducing covalently and non-covalently crosslinkable dopamine-modified crosslinkers and physically interactable linear poly(vinyl imidazole) (PVI). The resulting hydrogel adhesive exhibits high toughness and mechanical resilience due to the presence of a DN involving reversible physical intermolecular interactions such as hydrogen bonds, hydrophobic associations, cation-π interactions, π-π interactions, and chain entanglements. Moreover, the hydrogel adhesive achieves strong wet tissue adhesion through the polar hydroxyl groups of dopamine and the amine group of PVI. These mechanical attributes allow the proposed adhesive to effectively seal damaged tissues and promote wound healing by maintaining a moist environment.

Hydrophobic association: A facile approach to prepare physical cross-linked gelatin hydrogel with desirable thermal stability, flexibility and self-healing ability

Methacrylic anhydride was added to 20 % gelatin solution to prepare gelatin methacryloyl (GelMA) but an unexpected gelation process was observed within several minutes. The experimental data revealed that the methacryloyl substitution can increase the hydrophobicity of gelatin and the micellar diameter in solution. Therefore, we speculated that the methacryloyl substitution caused the formation of micellar cross-links based on the hydrophobic residues of gelatin and the methacryloyl groups, thus obtaining the hydrophobic association hydrogels. The thixotropic and tensile experiments confirmed that GelMA hydrogel possessed the features of hydrophobic association hydrogels like self-healing and stretchable abilities. The rheological experiments revealed that the gelation rate and the mechanical strength of the GelMA hydrogels were in direct proportion to the concentration of GelMA and the degree of methacryloyl substitution. GelMA hydrogels possessed desirable thermal stability that it didn't melt after being heated to 90 °C. Furthermore, the MTT assays and calcein AM/PI staining revealed that GelMA hydrogel was biocompatible. These results collectively confirm that the hydrophobic association is a prospective and facile approach to prepare gelatin hydrogel with desirable properties for further application.

A micro-crosslinked amphoteric hydrophobic association copolymer as high temperature- and salt-resistance fluid loss reducer for water-based drilling fluids

During ultradeep oil and gas drilling, fluid loss reducers are highly important for water-based drilling fluids, while preparing high temperature- and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge. Herein, a micro-crosslinked amphoteric hydrophobic association copolymer (i.e., DADC) was synthesized using N,N-dimethyl acrylamide, diallyl dimethyl ammonium chloride, 2-acrylamido-2-methylpropane sulfonic acid, hydrophobic monomer, and pentaerythritol triallyl ether crosslinker. Due to the synergistic effects of hydrogen bonds, electrostatic interaction, hydrophobic association, and micro-crosslinking, the DADC copolymer exhibited outstanding temperature- and salt-resistance. The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance. The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds, which bring more negative charge to the bentonite, thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids. Moreover, the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties (FLHTHP = 12 mL) after aging at high temperatures (up to 200 °C) and high salinity (saturated salt) environments. Therefore, this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents, demonstrating good potential applications in deep and ultradeep drilling engineering.

Acid-Induced Gelation of Carboxymethylcellulose Solutions.

The present work offers a comprehensive description of the acid-induced gelation of carboxymethylcellulose (CMC), a water-soluble derivative of cellulose broadly used in numerous applications ranging from food packaging to biomedical engineering. Linear viscoelastic properties measured at various pH and CMC contents allow us to build a sol-gel phase diagram and show that CMC gels exhibit broad power-law viscoelastic spectra that can be rescaled onto a master curve following a time-composition superposition principle. These results demonstrate the microstructural self-similarity of CMC gels and inspire a mean-field model based on hydrophobic interchain association that accounts for the sol-gel boundary over the entire range of CMC content under study. Neutron scattering experiments further confirm this picture and suggest that CMC gels comprise a fibrous network cross-linked by aggregates. Finally, low-field NMR measurements offer an original signature of acid-induced gelation from a solvent perspective. Altogether, these results open avenues for the precise manipulation and control of CMC-based hydrogels.

Residue-Free and Recyclable Starch-Based Flocculants for Dye Wastewater Flocculation.

Flocculants are crucial agents in wastewater treatment because they can remove oppositely charged impurities effectively and swiftly. However, flocculation also inevitably causes secondary contamination due to the residual properties, nonreusability, and nondegradability of traditional flocculant molecules. Herein, an ecofriendly starch-based flocculant, i.e., 2,4-bis(dimethylamino)-[1,3,5]-triazine-6-starch, was synthesized via a preactivation-etherification strategy. The large molecular weight property of the flocculant produced by this method enhances the intermolecular hydrophobic association, achieving complete phase separation of all flocculant molecules from water and residue-free flocculation for the first time. Importantly, a large molecular weight tertiary amine starch-based flocculant (LMTS) exhibits a remarkable flocculation capacity of over 1800 mg·g-1 for dye wastewater, which is significantly higher than that of traditional polyacrylamide and polyaluminum chloride flocculants. Furthermore, the LMTS flocculant could be recycled by pH adjustment, and its structural stability ensured sustained reusability. This high-performance residue-free biomass-based flocculant offers a green advance for wastewater treatment.

Hydrophobic Association Hydrogel Enabled by Multiple Noncovalent Interactions for Wearable Bioelectronics in Amphibious Environments

Hydrophobic Association Hydrogel Enabled by Multiple Noncovalent Interactions for Wearable Bioelectronics in Amphibious Environments

In-silico Design, ADMET Screening, Prime MM-GBSA Binding Free Energy Calculation and MD Simulation of Some Novel Phenothiazines as 5HT6R Antagonists Targeting Alzheimer's Disease.

Alzheimer's disease is a type of dementia that affects neuronal function, leading to a decline in cognitive functions. Serotonin-6 (5HT6) receptors are implicated in the etiology of neurological diseases. 5HT6 receptor antagonists act as anti-dementia agents. 7YS6 represents a membrane protein, and amplification and overexpression of this protein are associated with Alzheimer's disease. Coumarin-fused phenothiazines are significant anti-Alzheimer's agents due to their inhibitory activity on the Serotonin- 6 receptor. Numerous previously unreported Coumarin-substituted Phenothiazines [A2 to A50] were designed using in-silico methods to evaluate their 5HT6 receptor antagonistic activity. Molecular modeling techniques were employed to study the ligands [A2 to A50] in interaction with the Serotonin-6 receptor (PDB ID: 7YS6) using Schrödinger Suite 2019-4. Molecular modeling studies of the designed ligands [A2 to A50] were conducted using the Glide module. In-silico ADMET screening was performed using the QikProp module, and binding free energy calculations were carried out using the Prime MM-GBSA module within the Schrödinger Suite. The binding affinity of the designed ligands [A2 to A50] towards 5HT6 receptors was determined based on Glide scores. Subsequently, ligand A31 underwent a 100 ns molecular dynamics simulation using the Desmond module of Schrödinger Suite 2020-1, which is based in New York, NY. The majority of the designed ligands exhibited strong hydrogen bonding interactions and hydrophobic associations with the serotonin-6 receptor, which hinder its activity. These ligands achieved remarkable Glide scores within the range of -4.2859 to -7.7128, in comparison to reference standards such as Idalopirdine (-7.78149), Intepirdine (-5.20103), Latrepirdine (-5.54853), and the co-crystallized ligand (-7.02889). In-silico ADMET properties for these ligands fell within the recommended values for drug-likeness. It is worth noting that the MM-GBSA binding free energy of the most potent inhibitor was positive, indicating a strong binding interaction. Additionally, the dynamic behavior of the protein (7YS6)-ligand (A31) complex was studied by subjecting ligand A31 to a 100 ns molecular dynamics simulation. The results of this study reveal strong evidence supporting the potential of coumarin- substituted phenothiazine derivatives as effective Serotonin-6 receptor antagonists. Ligands [A2 to A50], which exhibited noteworthy Glide scores, hold promise for significant anti- Alzheimer activity. Further in-vitro and in-vivo investigations are warranted to explore and confirm their therapeutic potential.

PH-Induced Mechanical Transition in Polyion Complex Hydrogels: Shifting from Ionic Association to Hydrophobic Association

pH-Induced Mechanical Transition in Polyion Complex Hydrogels: Shifting from Ionic Association to Hydrophobic Association