Understanding the mechanisms of pH-responsiveness allows researchers to design and fabricate membranes with specific functionalities for various applications. The pH-responsive membranes (PRMs) are particular categories of membranes that have an amazing aptitude to change their properties such as permeability, selectivity and surface charge in response to changes in pH levels. This review provides a brief introduction to mechanisms of pH-responsiveness in polymers and categorizes the applied polymers and functional groups. After that, different techniques for fabricating pH-responsive membranes such as grafting, the blending of pH-responsive polymers/microgels/nanomaterials, novel polymers and graphene-layered PRMs are discussed. The application of PRMs in different processes such as filtration membranes, reverse osmosis, drug delivery, gas separation, pervaporation and self-cleaning/antifouling properties with perspective to the challenges and future progress are reviewed. Lastly, the development and limitations of PRM fabrications and applications are compared to provide inclusive information for the advancement of next-generation PRMs with improved separation and filtration performance. 

pH-responsive membranes: Mechanisms, fabrications, and applications

Utilizing remarkable polymer matrix and efficient filler to propose an ingenious strategy for designing composite films synergistically with high electromagnetic interference shielding effectiveness (EMI SE) and thermal conductivity. Herein, a novel type of flexible composite film based on syndiotacticity-rich poly (vinyl alcohol) (sPVA)/modified MXene sediment (mMS) is fabricated through an alternating casting approach. The sPVA/mMS multilayered film containing effective noncovalent combining between sPVA layer and mMS layer not only presents a high strength of ∼66.3 MPa but also possesses a superior electrical conductivity of 683 S/m. Notably, the mMS layer with dense conductive and thermal networks endows the 95-μm-thick composite film with the synergy of favorable EMI SE (∼15.8 dB) in the X band and impressive in-plane thermal conductivity (3.31 W/mK, enhanced by ∼2365%). Moreover, this multilayered architecture realizes multiple internal reflection-absorption of microwaves and efficient heat dissipation, while confers the film with advantageable flame retardancy and significant water resistance. Therefore, sPVA-based composite films from MS provide a promising solution for the development of multifunctional polymeric materials tailored for upcoming electronic devices in challenging environments. 

Multifunctional syndiotacticity-rich poly (vinyl alcohol)/MXene sediment for multilayered composite films with effective electromagnetic interference shielding and thermal conductivity

Interlayered thin-film composite (TFC) membranes are promising in overcoming the permeability-selectivity tradeoff of conventional membranes. However, fabricating high-performance TFC membranes with tunable interlayer spacing and antifouling properties remains challenging. Here we develop a high-performance self-cleaning TFC graphene oxide (GO) membrane by employing multifunctional bismuthyl bromide (BiOBr) nanosheets to construct a unique photocatalytic GO@BiOBr interlayer. BiOBr has multiple functions, including regulating the GO nanosheet spacing (i.e., the channel size), mediating the surface properties of the interlayer to enable a desirable selective layer during interfacial polymerization, and imparting photocatalytic properties to the TFC membrane. Because of the dimensional difference between GO and BiOBr nanosheets, the spacing of the dual 2D nanosheets (GO and BiOBr) can be finely tailored by adjusting BiOBr loading. Coupling of the 2D nanosheets enables tunable interlayer properties and a highly thin and selective rejection layer, leading to significantly enhanced separation performance of the TFC membrane. The GO@BiOBr interlayered TFC membrane shows a water permeability of 29.9 L·m−2·h−1·bar−1, which is six times higher than the TFC membrane without an interlayer. The GO@BiOBr interlayered TFC membrane displays 100% rejections to various small molecules (e.g., Rhodamine B, Basic Blue 26 and Ofloxacin). The rise of BiOBr loading in the GO@BiOBr composite increases the interlayer spacing of the dual 2D nanosheets, likely leading to more monomer diffusion and eruptive interfacial polymerization. As a result, thicker and rougher polyamide layers are formed, resulting in decreased water permeability of the TFC membrane. This study presents a viable approach for engineering the next generation of high-performance self-cleaning TFC membranes for reverse osmosis, forward osmosis and nanofiltration within the realm of water treatment. 

Dual 2D nanosheets with tunable interlayer spacing enable high-performance self-cleaning thin-film composite membrane

Covalent organic frameworks (COFs) with tunable pore sizes and ordered structures are ideal materials for engineering nanofiltration (NF) membranes. However, most of the COFs prepared by solvothermal synthesis are unprocessable powders and fail to form well-structured membranes, which seriously hinders the development of COF NF membranes. Herein, colloidal 2D-COFs with processable membrane formation ability were synthesized by oil-in-water emulsion interfacial polymerization technology. COF NF membranes with tailored thickness and surface charge were fabricated via a layer-by-layer (LBL) assembly strategy. The prepared COF NF membrane achieved precise sieving of dye molecules with high permeance (85 L·m-2·h-1·bar-1). In this work, the strategy of prepared COF NF membranes based on colloid 2D-COF LBL assembly is proposed for the first time, which provides a new idea for the on-demand design and preparation of COF membranes for precise molecular sieving.

Colloidal 2D Covalent Organic Framework-Tailored Nanofiltration Membranes for Precise Molecular Sieving.

Ti3C2Tx MXene/Fe3O4/Carbon Fiber Fabric/Water Polyurethane Composite Fabrics for Electromagnetic Interference Shielding and Thermal Management

The integration and miniaturization of contemporary electronics have led to significant challenges in dealing with electromagnetic (EM) radiation and heat accumulation. Despite these issues, achieving high thermal conductivity (TC) and electromagnetic interference (EMI) shielding effectiveness (SE) in polymer composite films remains an exceptionally difficult task. In this work, we used a straightforward in situ reduction process and a vacuum-drying method to successfully prepare a flexible Ag NPs/chitosan (CS)/PVA nanocomposite with three-dimensional (3D) conductive and thermally conductive network architectures. The 3D silver pathways formed by attaching to the chitosan fibers endow the material with simultaneous exceptional TC and EMI capabilities. At a silver concentration of 25 vol %, the TC of Ag NPs/CS/PVA nanocomposites reaches 5.18 W·m-1·K-1, exhibiting an approximately 25 times increase compared to CS/PVA composites. The electromagnetic shielding performance of 78.5 dB significantly outperforms the specifications of standard commercial EMI shielding applications by a significant margin. Additionally, Ag NPs/CS/PVA nanocomposites have greatly benefited from microwave absorption (SEA), effectively impeding the transmission of EM waves and reducing the reflected secondary EM wave pollution. Meanwhile, the composite material still maintains good mechanical properties and bendability. This endeavor helped develop malleable and durable composites that possess superior EMI shielding capabilities and intriguing heat dissipation properties using innovative design and fabrication methods.

Eco-Friendly Silver Nanoparticles/Chitosan/Poly(vinyl alcohol) Composites Exhibit Remarkable EMI Shielding Capabilities and Outstanding Thermal Conductivities.

Membrane fouling, the accumulation of material on the membrane surface, has been a challenge that limits the application of reverse osmosis technology. Ordinary cleaning processes do not remove contaminants from the membrane surface. To effectively clean a membrane, we fabricated a sacrificial multilayer polyelectrolyte coating based on a layer-by-layer assembly approach using chitosan (CS) and tannic acid (TA) on the membrane surface. The CS/TA coated membranes represent a superior permeance flux of 64 L m−2 h−1 with a clear NaCl rejection of 98.89 %. Meanwhile, the membrane surface hydrophilicity was enhanced due to the abundant amino and hydroxyl groups, which shows superior anti-fouling properties against proteins, polysaccharides, and surfactant. Moreover, the coatings were unstable, which would decompose at pH 8.5. The degradation endows the coated membranes approving long-term anti-fouling performance, which the permeance recovery reaching up to 85 %. Constructing pH-responsive smart coatings provides a promising route to address membrane fouling. It can be upscaled in numerous practical applications like sensors, medical devices, and drug delivery. 

Polyelectrolyte-based antifouling and pH-responsive multilayer coatings for reverse osmosis membrane

With the growing demands in electronics, communications, and energy, conductive composites face a daunting challenge as criteria for conductivity and mechanical properties rise. Extensive search on nanocomposites and amorphous metals has been motivated by the quest for a conductive material that can enhance strength and deformability. However, finding conductive materials that can overcome the drawbacks of their conventional counterparts and exhibit great strength, toughness and quick charge transmission while accomplishing large-scale production remains a significant challenge. This paper describes an approach to high-temperature flexible conductive materials by utilizing composites composed of aramid nanofiber (ANF) and silver nanoparticles (Ag NPs). The ANF is derived from macro-aramid fibers and retains its excellent mechanical properties and heat resistance. Within the composite, Ag NPs effectively enter the special nanofiber matrix to build a tightly connected conductive pathway on the ANF, thus facilitating efficient charge transport. The resulting Ag-ANF composite films exhibit an impressive electrical conductivity of 36,989.68 S m−1 and a tensile strength of 30.3 MPa. Additionally, they provide outstanding EMI shielding with a value of 107.9 dB. This significant achievement opens up the possibility of metallizing the surface of insulated polymer fibers, thereby enabling effective EMI shielding applications even in challenging and extreme conditions. 

Metal-Grade Laminated Nanofiber Films with Outstanding EMI Shielding Performances and High-Temperature Resistance

Covalent organic frameworks (COFs), with ordered pores and well-defined topology, are ideal materials for nanofiltration (NF) membranes because of their capacity of transcending the permeance/selectivity trade-off predicament. However, most reported COF-based membranes are focused on separating molecules with different sizes, resulting in low selectivity to similar molecules with different charges. Here, the negatively charged COF layer was fabricated in situ on a microporous support for the separation of molecules with different sizes and charges. Ultrahigh water permeance (216.56 L m-2 h-1 bar-1) was obtained because of the ordered pores and excellent hydrophilicity, which exceeds that of most membranes with similar rejections. For the first time, we used multifarious dyes with different sizes and charges, for the investigation of the selectivity behavior caused by the Donnan effect and size exclusion. The obtained membranes represent superior rejections to negatively and neutrally charged dyes larger than 1.3 nm, while positively charged dyes with a size of 1.6 nm can pass through the membrane, resulting in the separation of negative/positive mixed dyes with similar molecular sizes. This strategy of combining the Donnan effect and size exclusion in nanoporous materials may evolve into a generic platform for sophisticated separation.

Donnan Effect-Engineered Covalent Organic Framework Membranes toward Size- and Charge-Based Precise Molecular Sieving.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of {limit} columns in the table. Remove at least 1 column to add or create another one.

Han Jiang

Author Tools

Chat about Author

Papers

Eco-Friendly Silver Nanoparticles/Chitosan/Poly(vinyl alcohol) Composites Exhibit Remarkable EMI Shielding Capabilities and Outstanding Thermal Conductivities.

Polyelectrolyte-based antifouling and pH-responsive multilayer coatings for reverse osmosis membrane

Metal-Grade Laminated Nanofiber Films with Outstanding EMI Shielding Performances and High-Temperature Resistance

Donnan Effect-Engineered Covalent Organic Framework Membranes toward Size- and Charge-Based Precise Molecular Sieving.