Turing Structure Research Articles

Lysine-regulated turing structure membrane via interfacial polymerization for enhanced Li+/Mg2+ separation

The development of advanced membranes with precise ion selectivity is essential for efficient Li+/Mg2+ separation. In this study, we synthesized a novel Lys-TMC membrane via a nucleophilic addition reaction between Lysine and trimesoyl chloride (TMC), yielding in a negatively charged surface interconnected by amide bonds. We systematically investigated the effects of varying Lys:TMC ratios on the membrane’s chemical structure, surface morphology, and ion separation performance. Our results revealed that the degree of cross-linking increases initially with the Lysine content, reaching an optimum at a Lys:TMC ratio of 10:1, where the membrane exhibited prominent Turing patterns on its surface. These patterns were critical for achieving effective ion separation. In contrast, excessive Lysine led to spontaneous polymerization, resulting in irregular ‘stone-like’ structures and the loss of Turing patterns. The optimally cross-linked Lys-TMC membrane displayed superior Li+/Mg2+ separation performance, highlighting the crucial role of controlled cross-linking and Turing structure formation in enhancing ion selectivity. This work provides a mechanistic understanding of the relationship between Turing structure formation and ion sieving performance, offering a promising strategy for designing advanced separation membranes.

Turing structured nanofiltration membrane fabricated by sulfonated cellulose nanocrystals mediated interfacial polymerization for enhanced permeability separation performance

Preparing Turing structure nanofiltration (NF) membrane is a representative strategy to obtain high permeability and selectivity. However, getting a tailored Turing structure by adjusting the interfacial polymerization (IP) process remains a significant challenge. Herein, sulfonated cellulose nanocrystals (S-CNC) with excellent hydrophilicity and negative surface charges were selected as aqueous phase additives to explore their influence on the morphology and composition of polyamide (PA) layer as well as its NF performance. It was found the surface morphology of the PA layer was effectively changed by adjusting the content of S-CNC in the aqueous phase. As the content of S-CNC increased, the Turing structure underwent a series of evolutions, from an “octopus leg structure” to a densely packed ridge-valley structure to a large ridge-valley structure filled with dense nodular particles. Finally, it changed back to the typical PA morphology of densely distributed nodular particles. By exploring the interaction between S-CNC and piperazine (PIP), it was demonstrated that the hydrogen bond and electrostatic interaction between S-CNC and PIP synergistically inhibited the diffusion of PIP, thus resulting in various Turing structures. Benefiting from the unique Turing structure, the prepared SCNF-10 NF membranes showed excellent permeability and separation properties with pure water permeability (PWP) of 16.9 LMH bar−1 and Na2SO4 rejection rate of 98.0 %. SCNF-10 NF membranes also exhibited good selectivity with a separation factor of 34.6 for mono-bivalent salts and long-term permeation stability. It is anticipated that this regulation strategy for various Turing structures preparation can provide a deeper understanding of the application of cellulose nanocrystals to NF membranes in the later stage, which will also promote the development of the high performance of NF membranes.

Prompted by surface-engineered honeycomb Turing nanostructures: Reflections on polyamide structure, growth and performance

The robust correlation between the performance of thin-film composite (TFC) reverse osmosis membranes and the polyamide (PA) active layer determines the necessity of precise design of the PA layer, and this regulation primarily involves the surface morphology and internal characteristics of the PA layer. In this study, we fabricated honeycomb Turing structure or nanovoid-rich TFC series membranes using polar/nonpolar organic phase additives. Characterization and simulation results confirmed that the enhancement of membrane performance relied more on the abundant nanovoids within the PA layer rather than the ordered honeycomb lattice surface. Notably, the TFC-nDCE membrane with multilayer nanovoids exhibited an approximately 89 % improvement in water permeability while maintaining satisfactory salt rejection (98.29 %). We emphasized the significant role of nanovoids in the diffusion process of amine monomers and investigated the potential relationship between nanovoids and the degree of surface cross-linking. Building upon this, a new insight into the formation of nanovoids induced by PA anisotropic growth was presented through a careful analysis of the amine monomer diffusion rate and the morphological evolution of nanovoids. The structure-property relationship between internal structures, surface morphologies, and performances was systematically and thoroughly investigated, pointing out the direction for the rational design of TFC membranes.

Effect of poly(2-(dimethylamino)ethyl methacrylate) brush-grafted graphene oxide on polyamide layer formation and nanofiltration performance

Thin film composite (TFC) membrane performance is often restricted by permeability and selectivity trade-off effect, even with the modification of nanoparticles. Graphene oxide-poly(2-(dimethylamino)ethyl methacrylate) (GO-PDMAEMA) with brush structure has abundant hydrophilic oxygen-containing functional groups and amine groups. It was synthesized via the atom transfer radical polymerization method and incorporated into TFC polyamide layer using interfacial polymerization. The GO-PDMAEMA-modified thin film nanocomposite membranes (TFNG-P) with Turing structure and higher surface hydrophilicity enhanced water permeability by 40.7–55%, with relatively low nanoparticle loading (0.005–0.02 wt%). Besides, TFNG-P2 (0.01 wt% GO-PDMAEMA) has the highest Na2SO4 rejection (97.8%), 4.4% higher than TFC. The PDMAEMA brushes on GO with additional amine groups promoted the amide linkage and increased the PA layer cross-linking by 16.2%. The higher cross-linking did not negatively affect the membrane flux, as the better hydrophilicity offset this effect. The utilization of the modified membranes in the treatment of palm oil mill effluent demonstrated enhanced resistance to fouling with TFNG-P2, which exhibited the highest flux recovery rate, reaching 89.4%. Thus, this study showed GO modification by grafting PDMAEMA brushes had enhanced the membrane properties, resulting in TFNG-P with higher permeability, promising separation and antifouling performance.

7.9 µm Turing Membranes with High Ion Conductivity for High Power Density Zinc‐Based Flow Battery

AbstractIon conductive membranes with rapid and selective ion transport are in high demand for high‐power energy storage devices. Surface periodic Turing microstructures are scientifically compelling for their high specific surface area which can promote ion transport of membranes. Here, high‐conductivity thin Turing membranes prepared by Co2+ coordination with polybenzimidazole (OPBI) are designed and their efficient ion transport in the alkaline zinc‐iron flow battery (AZIFB) is demonstrated. In this design, the Turing structure increases the effective contact area with the electrolyte, and the 7.9 µm thickness shortens the transmembrane pathway for ions. Molecular dynamics simulations further show that Co2+‐coordination enlarges the inner‐chain volume of membranes and forms continuous water channels for rapid ion transport. The boosting effect of membranes with high ion conductivity is proven by the peak power density and energy efficiency of the AZIFB, which shows an ultrahigh peak power density of 1147 mW cm−2 and demonstrates an energy efficiency of 80% even at a high current density of 200 mA cm−2.

Preparation of thin-film composite membrane with Turing structure by PEO-assisted interfacial polymerization combined with choline chloride modification to improve permeability

BackgroundThe speed of the interfacial polymerization reaction is considered to be the decisive factor for the thickness and surface morphology of the polyamide layer. The reaction rate can be controlled by controlling the diffusion rate of the aqueous monomer. MethodsHere, firstly, polyethylene oxide was added into the aqueous solution to increase the viscosity of the aqueous phase to reduce the reaction rate. Then choline chloride (CC) was grafted on the surface of the nascent polyamide membrane by a surface grafting method for secondary modification. A polyamide nanofiltration membrane with a special Turing structure was prepared on the surface of polyethersulfone support membrane. The desalination performance of composite membrane was investigated. Significant findingsThe results showed that the addition of PEO resulted in the regular Turing structure on the surface of the composite membrane. When the addition amount reached 1%, the performance of the composite membrane was the best. After the secondary modification of CC, the rejection rate of Na2SO4 was more than 96%, and the permeation flux could reach 125.9 L/(m2·h·MPa). It is expected to be applied in the fields of seawater desalination and sewage purification.

Microporous organic nanotube assisted design of high performance nanofiltration membranes

Microporous organic nanotubes (MONs) hold considerable promise for designing molecular-sieving membranes because of their high microporosity, customizable chemical functionalities, and favorable polymer affinity. Herein, we report the use of MONs derived from covalent organic frameworks to engineer 15-nm-thick microporous membranes via interfacial polymerization (IP). The incorporation of a highly porous and interpenetrated MON layer on the membrane before the IP reaction leads to the formation of polyamide membranes with Turing structure, enhanced microporosity, and reduced thickness. The MON-modified membranes achieve a remarkable water permeability of 41.7 L m−2 h−1 bar−1 and high retention of boron (78.0%) and phosphorus (96.8%) at alkaline conditions (pH 10), surpassing those of reported nanofiltration membranes. Molecular simulations reveal that introducing the MONs not only reduces the amine molecule diffusion toward the organic phase boundary but also increases membrane porosity and the density of water molecules around the membrane pores. This MON-regulated IP strategy provides guidelines for creating high-permeability membranes for precise nanofiltration.

Poly(caffeic acid) as interlayer to enhance nanofiltration performance of polyamide composite membrane

It is a challenge to develop nanofiltration (NF) membranes with simultaneously high permeability and excellent selectivity for water desalination. In this work, a composite NF membrane with an interlayer was prepared in order to overcome the upper bound of permeability-selectivity. Poly(caffeic acid) (PCA) was first deposited on the surface of polyacrylonitrile (PAN) ultrafiltration membrane to construct an interlayer, and then polyamide (PA) layer was formed on the PCA interlayer to fabricate the composite membrane (PAN-PCAn-PA). The chemical structure, morphology and surface properties of the composite membranes with and without the interlayer were compared. In addition, the preparation conditions and separation properties of the composite membranes were investigated. The results suggested that a loose “gutter” interlayer and a nanoscale Turing structure on the membrane surface were constructed due to the hydrophilic and electronegative PCA, which optimized the transport channels of water molecules. Hence, the water permeance of PAN-PCA2-PA membrane was 17.7 L·m−2·h−1·bar−1, which was 86% higher than that of PAN-PA membrane. Meanwhile, the PAN-PCA2-PA membrane exhibited high rejection ratio of Na2SO4 (98.9%), excellent selectivity for Cl‐/SO42‐ (75.9) and long-term filtration stability, which showed its potential for practical applications in water desalination.

MOFs-mediated nanoscale Turing structure in polyamide membrane for enhanced nanofiltration

This work reported the successful preparation of a novel nano-Turing structure polyamide membrane. By introducing polyvinylpyrrolidone (PVP) into UiO-66-NH2, PVP-UiO-66-NH2 with high water hydrophilicity and low particle size was synthesized. The aqueous phase dispersion containing PVP-UiO-66-NH2 was loaded on the support through vacuum filtration method, and PVP-UiO-66-NH2 was fused in the polyamide layer via traditional interfacial polymerization (IP) technology. The existence of PVP-UiO-66-NH2 induced the occurrence of “local activation and lateral inhibition” in the IP system, resulting in the appearance of nano-Turing structure on the membrane surface. The successful preparation of PVP-UiO-66-NH2@polyamide composite membrane with uniform distribution of PVP-UiO-66-NH2 was proved. The PVP-UiO-66-NH2@polyamide composite membrane showed excellent water permeability of 32.95 L·m−2·h−1·bar−1 and stable Na2SO4 removal rate of 99.35 %, compared with 17.56 L·m−2·h−1·bar−1 and 99.56 % of pure polyamide membrane under the same conditions. In addition, the PVP-UiO-66-NH2@polyamide composite membrane exhibited excellent long-term filtration stability, thermal stability and antibacterial property.

Homogeneous solution assembled Turing structures with near zero strain semi-coherence interface

Turing structures typically emerge in reaction-diffusion processes far from thermodynamic equilibrium, involving at least two chemicals with different diffusion coefficients (inhibitors and activators) in the classic Turing systems. Constructing a Turing structure in homogeneous solutions is a large challenge because of the similar diffusion coefficients of most small molecule weight species. In this work, we show that Turing structure with near zero strain semi-coherence interfaces is constructed in homogeneous solutions subject to the diffusion kinetics. Experimental results combined with molecular dynamics and numerical simulations confirm the Turing structure in the spinel ferrite films. Furthermore, using the hard-soft acid-base theory, the design of coordination binding can improve the diffusion motion of molecules in homogeneous solutions, increasing the library of Turing structure designs, which provides a greater potential to develop advanced materials.

Mofs-Mediated Nanoscale Turing Structure in Polyamide Membrane for Enhanced Nanofiltration

Mofs-Mediated Nanoscale Turing Structure in Polyamide Membrane for Enhanced Nanofiltration

Mofs-Mediated Nanoscale Turing Structure in Polyamide Membrane for Enhanced Nanofiltration

Mofs-Mediated Nanoscale Turing Structure in Polyamide Membrane for Enhanced Nanofiltration

Novel Poly(piperazinamide)/poly(m-phenylene isophthalamide) composite nanofiltration membrane with polydopamine coated silica as an interlayer for the splendid performance

Nanofiltration (NF) is a potential separation technology in the field of water treatment. However, NF membrane generally has the bottleneck problems of low permeability and poor selective separation. Therefore, this study proposed to use polydopamine coated silica microspheres as the intermediate layer to modify the poly(m-phenylene isophthalamide) (PMIA) substrate, then to prepare poly(piperazinamide) composite NF membrane via interfacial polymerization technique. Because both dopamine and silica contain a large number of hydroxyl groups, which can limit the diffusion of aqueous monomers to the water/oil boundary due to the hydrogen bonding force. The obtained NF membrane presented a nano-tubular Turing structure. As a result, the membrane exhibited extremely high permeability with the pure water flux of 31.37 ± 1.06 LMH/bar, and the corresponding rejection to Na2SO4 could reach to 97.0%, which was three times that of traditional polyamide NF membrane. Moreover, the performance of one-valent/bivalent salt was excellent. The composite nanofiltration membrane made of polydopamine coated silica as the intermediate layer provides a potential strategy to construct polyamide membrane with improved permeation and selectivity, which will be beneficial to save energy consumption during the actual application.

Complex spatiotemporal dynamics of a harvested prey–predator model with Crowley–Martin response function

The formation of spatiotemporal patterns is one of the most important part in the prey–predator dynamical system. In this paper, we investigate the local dynamics as well as the Turing structure through diffusion-driven instability by taking more general Crowley–Martin response function in the prey–predator system with the effect of linear harvesting of prey and predator. All the feasible equilibrium points are extracted. Boundedness, persistence, local and global stability, and Hopf bifurcation are established for some suitable parametric conditions. The parametric space for which the Turing spatial structure takes place is found out. Different kinds of patterns are demonstrated depending on the ecological parameters of the local system and diffusion coefficients.

Introducing gel-based UiO-66-NH2 into polyamide matrix for preparation of new super hydrophilic membrane with superior performance in dyeing wastewater treatment

Gel-based ultra-small size UiO-66-NH2, a zirconium metal-organic framework (Zr-MOF), was synthesized through a new energy efficient method. Then, this inherent hydrophilic nanomaterial with a 20 nm average size was incorporated into polyamide (PA) layer to form a thin film nanocomposite (TFN) membrane. Characterization results revealed that the TFN membranes had a continuous striped Turing structure and a super hydrophilic surface, with contact angle below 11⁰. The membranes were found to have a good performance in dye/salt fractionation. For instance, when the gel-based UiO-66-NH2 loading amount was 0.1 wt% in the organic solution during interfacial polymerization (TFN-0.1), the permeance and rejection were 31.6 L/m2.h.bar and 92.2%, 29.7 L/m2.h.bar and 95.9%, and 27.2 L/m2.h.bar and 99.6% for methyl orange (MO, 327 Da), sunset yellow (SY, 452 Da), and Congo red (CR, 696 Da), respectively. A remarkable result was obtained for the challenging separation between NaCl and a small size dye, i.e., MO: 91.8% MO rejection along with 9.7% NaCl rejection. Moreover, the TFN-0.1 membrane was found to have a high stability in a 3 days continuous test to separate NaCl from CR/NaCl solution. Furthermore, the membrane has a good antifouling performance with 88% flux recovery. Thus, the prepared membrane has potential for dyeing wastewater treatment.

MOF-Mediated Interfacial Polymerization to Fabricate Polyamide Membranes with a Homogeneous Nanoscale Striped Turing Structure for CO2/CH4 Separation.

Control of the surface morphology of polyamide membranes fabricated by interfacial polymerization is of great importance in dictating the separation performance. Herein, polyamide membranes with a specific nanoscale striped Turing structure are generated through facile addition of Zr-based metal-organic framework UiO-66-NH2 in the aqueous triethylenetetramine phase. Interestingly, accompanied by the degradation of UiO-66-NH2 in aqueous solution, an intermediate complex is in situ formed through the strong interaction between the Zr metal center and the amine group from triethylenetetramine, which can lower amine diffusion and induce a local interfacial reaction, contributing to the generation of a homogeneous nanoscale striped Turing structure. The resulting membranes are used for CO2/CH4 gas separation. Compared with the parent polyamide membrane displaying a CO2/CH4 selectivity of 43.1 and a CO2 permeance of 31.5 GPU, the membrane with 0.02 wt % of UiO-66-NH2 introduced into the aqueous phase shows a higher CO2/CH4 selectivity of 58.3, along with a CO2 permeance of 27.1 GPU. Additionally, when 0.1 wt % of UiO-66-NH2 is incorporated into the aqueous phase, the membrane exhibits a combination of a higher CO2/CH4 selectivity and an enhanced CO2 permeance in contrast with the parent polyamide membrane.

Template-free, microscale dimple patterning of pure titanium surface through anodic dissolution using non-aqueous ethylene glycol-TiCl4 electrolytes

We report a single-step anodic dissolution route for the template-free patterning of pure titanium (Ti) surfaces into a microscale, dimpled topography using non-aqueous ethylene glycol-TiCl4 electrolytes. Anodic dissolution of Ti metal (i.e. 0.04 M Ti4+) into a 40 EG:1 TiCl4 electrolyte was found to induce a predominant change in the anodic dissolution reaction of Ti metal, converting its surface morphology from a slightly-pitted, bright finish into a dimple-patterned surface. The dimple pattern, ca. 4.5 μm in size and 1 μm in cusp height, was found self-organised with no apparent relation to underlying metal grain structure and independent of the applied potential within the anodic current plateau. The origin of the dimple pattern is surmised to arise from a dynamic self-organisation of the anode film, resulting in a Turing structure.

An innovative strategy for improving the performance of forward osmosis membrane: stripe-like Turing structure constructed by introducing hydrophilic polyvinylpyrrolidone

Improving the performance of forward osmosis (FO) membranes has always been moving forward. Here we fabricate the novel Turing structures in the active layer (AL) of thin film composite (TFC) membrane through effectively introducing the polyvinylpyrrolidone (PVP) macromolecule with hydrophilicity both in the support layer (SL) and AL. The addition of PVP facilitates the formation of sponge-like pores in the SL and stripe-like Turing structures in the AL. The influence of PVP on the morphology and performance of the membranes was investigated by SEM, AFM, XPS, NMR, FTIR. Compared with the water flux (Jw) of the original composite membrane (approximately 25 L m−2 h−1), TFC-PVP (3:1) membrane with Turing structure achieved better performance (approximately 75 L m−2 h−1), and the reverse solute flux/water flux (Js/Jw) value was as low as 0.02 g/L. This study demonstrated that the Turing structures have a favorable effect on the performance of FO membrane and a promisingly practical application in water treatment.

A multifunctional polyimide nanofiber separator with a self-closing polyamide–polyvinyl alcohol top layer with a Turing structure for high-performance lithium–sulfur batteries

The development of commercial lithium–sulfur (Li–S) batteries is typically restricted by the intrinsic drawbacks of the dissolutiion and shuttling of lithium polysulfides (LPS) and the uncontrollable growth of lithium dendrites.

Preparation of Sulfonated Graphene Oxide Modified Composite Nanofiltration Membrane and Application in Salts Separation

In recent years, water resources are in short supply and seriously polluted. Increasingly more attention has been paid to the process of salt separation. The surface of the nanofiltration (NF) membrane is usually charged and can selectively allow the permeation of different ions. Based on the different charges on the NF membrane surface, in order to achieve a good separation of salt, the prepared graphene oxide with the sulfonic acid group was introduced into NF membrane material. Additionally, the SGO modified composite NF membrane was prepared by interfacial polymerization. Zeta potential analysis showed that the charge on the surface of the prepared NF membrane was more negative than that of the NF membrane without SGO. The peak of the ester group in the FT-IR analysis indicated that the sulfonate group was involved in the polymerization reaction. A Turing structure present on the surface of the membrane was evident through SEM pictures of the membrane surface. At a pressure of 0.2 MPa, the pure water flux can reach 45.85 L·(m2·h)-1. The rejection of Na2SO4 was 98.23%, while that of NaCl was 24.93%. The 10 h operation can effectively separate SO42- and Cl-, which realized the salt recycling.