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1.
J Colloid Interface Sci ; 675: 883-892, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-39002238

RESUMO

The construction of solid-state electrolytes for flexible zinc-air batteries is extremely challenging. A flexible and highly conductive solid electrolyte designed with a "seaweed structure" is reported in this work. Sodium alginate serves as the backbone to form a robust network structure, and the grafted quaternary ammonium groups provide channels for rapid ion transport, achieving excellent flexibility and hydroxide conductivity. The conductivity of the modified electrolyte membrane (QASA) is 5.23 × 10-2 S cm-1 at room temperature and reaches up to 8.51 × 10-2 S cm-1 at 75 °C. In the QASA based battery, bending at any angle is realized, and the power density is up to 57.28 mW cm-2. This work provides a new way to prepare high conductivity, green solid-state zinc-air batteries, and opens up a research line of thought for flexible energy storage materials.

2.
Chemphyschem ; : e202400067, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38837278

RESUMO

Free crystal space in more than 600 chalcogenide structures taken out from the ICSD has been theoretically analyzed. As a result, wide voids and channels accessible for Na+-ion migration were found in 236 structures. Among them, 165 compounds have not been described in the literature as Na+-conducting materials. These materials have been subjected to stepwise quantitative calculations. The bond valence site energy method has enabled the identification of 57 entries as the most promising ion conductors in which the Na+-ion migration energy (Em) is less than 0.55 eV for 2D or 3D diffusion. The kinetic Monte-Carlo method has been carried out for these substances; as a result, resulting in nine of the most prospective compounds with Na+-ionic conductivity Ϭ≥10-4 S cm-1 at room temperature were selected, for which the density functional theory calculations have been performed yielding six best candidates. Additionally, a logarithmic relationship was established between the values of Em and the diffusion channel radii as well as a linear relationship between Ϭ and the void radius.

3.
Small ; : e2402035, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38770746

RESUMO

Solid-state batteries (SSBs) are under development as high-priority technologies for safe and energy-dense next-generation electrochemical energy storage systems operating over a wide temperature range. Solid-state electrolytes (SSEs) exhibit high thermal stability and, in some cases, the ability to prevent dendrite growth through a physical barrier, and compatibility with the "holy grail" metallic lithium. These unique advantages of SSEs have spurred significant research interests during the last decade. Garnet-type SSEs, that is, Li7La3Zr2O12 (LLZO), are intensively investigated due to their high Li-ion conductivity and exceptional chemical and electrochemical stability against lithium metal anodes. However, poor interfacial contact with cathode materials, undesirable lithium plating along grain boundaries, and moisture-induced chemical degradation greatly hinder the practical implementation of LLZO-based SSEs for SSBs. In this review, the recent advances in synthesis methods, modification strategies, corresponding mechanisms, and applications of garnet-based SSEs in SSBs are critically summarized. Furthermore, a comprehensive evaluation of the challenges and development trends of LLZO-based electrolytes in practical applications is presented to accelerate their development for high-performance SSBs.

4.
ChemSusChem ; : e202400641, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38717790

RESUMO

Understanding ionic conduction in layered double hydroxides (LDHs) is a crucial step towards utilizing them as solid, hydroxide ion-conducting electrolytes in energy conversion applications. We selectively modified the interlayer and external surfaces of MgAl LDHs with tris(hydroxymethyl)aminomethane (TRIS) ligands. By adjusting the concentration of the TRIS surface modifier, the LDH basal plane surfaces could be functionalized everywhere (internally and externally) or only externally. External modification resulted in loss of OH-conductivity compared to pristine LDHs, confirming that external platelet surfaces are the primary ion conduction pathway.

5.
Heliyon ; 10(9): e30691, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38756569

RESUMO

We investigated the reactivity of P2-type honeycomb layered oxides Na2Ni2TeO6 (NNTO) and Na2Zn2TeO6 (NZTO) co-fired at the temperature from 500 °C to 800 °C. From X-ray diffraction measurements, it was found that the reaction between NNTO and NZTO is unremarkable at the temperature below 700 °C. However, when annealed at 800 °C, they formed the solid-solution phase without any secondary phases. The NNTO and NZTO composite pellets co-fired at 800 °C showed sodium-ion conductivity well above 10-4 S cm-1 at room temperature, indicating that the solid-solution phase of NNTO and NZTO has good ionic conductivity. A maximum room temperature conductivity of 7.4 × 10-4 S cm-1 was confirmed at the mixing ratio NNTO: NZTO = 0.5 : 1.5. These results can be applied to the fabrication of all-solid-state batteries using NNTO as the cathode active material and NZTO as the solid electrolyte via a simple co-sintering process.

6.
Artigo em Inglês | MEDLINE | ID: mdl-38669089

RESUMO

We present the development of a platform of well-defined, dynamic covalent amphiphilic polymer conetworks (APCN) based on an α,ω-dibenzaldehyde end-functionalized linear amphiphilic poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) (PEG-b-PPG-b-PEG, Pluronic) copolymer end-linked with a triacylhydrazide oligo(ethylene glycol) triarmed star cross-linker. The developed APCNs were characterized in terms of their rheological (increase in the storage modulus by a factor of 2 with increase in temperature from 10 to 50 °C), self-healing, self-assembling, and mechanical properties and evaluated as a matrix for gel polymer electrolytes (GPEs) in both the stretched and unstretched states. Our results show that water-loaded APCNs almost completely self-mend, self-organize at room temperature into a body-centered cubic structure with long-range order exhibiting an aggregation number of around 80, and display an exceptional room temperature stretchability of ∼2400%. Furthermore, ionic liquid-loaded APCNs could serve as gel polymer electrolytes (GPEs), displaying a substantial ion conductivity in the unstretched state, which was gradually reduced upon elongation up to a strain of 4, above which it gradually increased. Finally, it was found that recycled (dissolved and re-formed) ionic liquid-loaded APCNs could be reused as GPEs preserving 50-70% of their original ion conductivity.

7.
Membranes (Basel) ; 14(4)2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38668113

RESUMO

In recent years, anion exchange membranes (AEMs) have aroused widespread interest in hydrogen production via water electrolysis using renewable energy sources. The two current commercial low-temperature water electrolysis technologies used are alkaline water electrolysis (AWE) and proton exchange membrane (PEM) water electrolysis. The AWE technology exhibited the advantages of high stability and increased cost-effectiveness with low hydrogen production efficiency. In contrast, PEM water electrolysis exhibited high hydrogen efficiency with low stability and cost-effectiveness, respectively. Unfortunately, the major challenges that AEMs, as well as the corresponding ion transportation membranes, including alkaline hydrogen separator and proton exchange membranes, still face are hydrogen production efficiency, long-term stability, and cost-effectiveness under working conditions, which exhibited critical issues that need to be addressed as a top priority. This review comprehensively presented research progress on AEMs in recent years, providing a thorough understanding of academic studies and industrial applications. It focused on analyzing the chemical structure of polymers and the performance of AEMs and established the relationship between the structure and efficiency of the membranes. This review aimed to identify approaches for improving AEM ion conductivity and alkaline stability. Additionally, future research directions for the commercialization of anion exchange membranes were discussed based on the analysis and assessment of the current applications of AEMs in patents.

8.
Int J Mol Sci ; 25(3)2024 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-38338873

RESUMO

State-of-the-art Li batteries suffer from serious safety hazards caused by the reactivity of lithium and the flammable nature of liquid electrolytes. This work develops highly efficient solid-state electrolytes consisting of imidazolium-containing polyionic liquids (PILs) and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). By employing PIL/LiTFSI electrolyte membranes blended with poly(propylene carbonate) (PPC), we addressed the problem of combining ionic conductivity and mechanical properties in one material. It was found that PPC acts as a mechanically reinforcing component that does not reduce but even enhances the ionic conductivity. While pure PILs are liquids, the tricomponent PPC/PIL/LiTFSI blends are rubber-like materials with a Young's modulus in the range of 100 MPa. The high mechanical strength of the material enables fabrication of mechanically robust free-standing membranes. The tricomponent PPC/PIL/LiTFSI membranes have an ionic conductivity of 10-6 S·cm-1 at room temperature, exhibiting conductivity that is two orders of magnitude greater than bicomponent PPC/LiTFSI membranes. At 60 °C, the conductivity of PPC/PIL/LiTFSI membranes increases to 10-5 S·cm-1 and further increases to 10-3 S·cm-1 in the presence of plasticizers. Cyclic voltammetry measurements reveal good electrochemical stability of the tricomponent PIL/PPC/LiTFSI membrane that potentially ranges from 0 to 4.5 V vs. Li/Li+. The mechanically reinforced membranes developed in this work are promising electrolytes for potential applications in solid-state batteries.


Assuntos
Líquidos Iônicos , Propano/análogos & derivados , Lítio , Eletrólitos , Íons , Poli A , Polímeros
9.
ACS Nano ; 18(8): 6016-6027, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38349043

RESUMO

Ion exchange membranes allowing the passage of charge-carrying ions have established their critical role in water, environmental, and energy-relevant applications. The design strategies for high-performance ion exchange membranes have evolved beyond creating microphase-separated membrane morphologies, which include advanced ion exchange membranes to ion-selective membranes. The properties and functions of ion-selective membranes have been repeatedly updated by the emergence of materials with subnanometer-sized pores and the understanding of ion movement under confined micropore ion channels. These research progresses have motivated researchers to consider even greater aims in the field, i.e., replicating the functions of ion channels in living cells with exotic materials or at least targeting fast and ion-specific transmembrane conduction. To help realize such goals, we briefly outline and comment on the fundamentals of rationally designing membrane pore channels for ultrafast and specific ion conduction, pore architecture/chemistry, and membrane materials. Challenges are discussed, and perspectives and outlooks are given.

10.
Adv Mater ; 36(15): e2305711, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38342600

RESUMO

High-performance proton exchange membrane (PEM) is crucial for the proton exchange membrane fuel cell (PEMFC). Herein, a novel "self-enhanced" PEM is fabricated for the first time, which is composed of perfluorinated sulfonic acid (PFSA) resin and its own nanofibers as reinforcement. With this strategy, the interfacial compatibility issue of conventional fiber-reinforced membranes is fully addressed and up to 80 wt% loading of PFSA nanofibers can be incorporated. Furthermore, on account of chain orientation within the PFSA nanofiber, single fiber exhibits super-high conductivity of 1.45 S cm-1, leading to state-of-the-art proton conductivity (1.1 S cm-1) of the as-prepared "self-enhanced" PEM so far, which is an order of magnitude increase compared with the bulk PFSA membrane (0.29 S cm-1). It surpasses any commercial PEM including the popular GORE-SELECT and Nafion HP membranes and is the only PEM with conductivity at 100 S cm-1 level. In addition, the mechanical strength and swelling ratio of membranes are both substantially improved simultaneously. Based on the high-performance "self-enhanced" PEM, high peak power densities of up to 3.6 W cm-2 and 1.7 W cm-2 are achieved in H2-O2 and H2-Air fuel cells, respectively. This strategy can be applied in any polymeric electrolyte membrane.

11.
Membranes (Basel) ; 14(1)2024 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-38248707

RESUMO

Novel composite membranes employing a poly(ether-block-amide) (PEBAX) copolymer and sulfonated montmorillonite (S-MMT) as a filler were developed. The ratio of polyether to polyamide blocks was investigated using PEBAX 2533 and PEBAX 4533 based on the membrane properties and performance. Additionally, the effect of the changing filler ratio was monitored. The interaction between the S-MMT as nanofiller and the polymer matrix of PEBAX2533 and PEBAX4533 as well as the crystalline nature and thermal and mechanical stability of the composite membranes were evaluated using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and tensile test. The composite membrane with 7 wt.% S-MMT showed the highest water uptake of 21% and 16% and an acceptable swelling degree of 16% and 9% for PEBAX 2533 and PEBAX 4533 composite membranes, respectively. In terms of water uptake and ion exchange capacity at room temperature, the new un-protonated membranes are superior to un-protonated Nafion. Meanwhile, with the same S-MMT content, the ion conductivity of PEBAX 2533 and PEBAX 4533 composite membranes is 2 and 1.6 mS/cm, and their ion exchange capacity is 0.9 and 1.10 meq/g.

12.
Small ; 20(2): e2305317, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37670223

RESUMO

Stimuli-responsive ion nanochannels have attracted considerable attention in various fields because of their remote controllability of ionic transportation. For photoresponsive ion nanochannels, however, achieving precise regulation of ion conductivity is still challenging, primarily due to the difficulty of programmable structural changes in confined environments. Moreover, the relationship between noncontact photo-stimulation in nanoscale and light-induced ion conductivity has not been well understood. In this work, a versatile design for fabricating guard cell-inspired photoswitchable ion channels is presented by infiltrating azobenzene-cross-linked polymer (AAZO-PDAC) into nanoporous anodic aluminum oxide (AAO) membranes. The azobenzene-cross-linked polymer is formed by azobenzene chromophore (AAZO)-cross-linked poly(diallyldimethylammonium chloride) (PDAC) with electrostatic interactions. Under UV irradiation, the trans-AAZO isomerizes to the cis-AAZO, causing the volume compression of the polymer network, whereas, in darkness, the cis-AAZO reverts to the trans-AAZO, leading to the recovery of the structure. Consequently, the resultant nanopore sizes can be manipulated by the photomechanical effect of the AAZO-PDAC polymers. By adding ionic liquids, the ion conductivity of the light-driven ion nanochannels can be controlled with good repeatability and fast responses (within seconds) in multiple cycles. The ion channels have promising potential in the applications of biomimetic materials, sensors, and biomedical sciences.

13.
Small Methods ; 8(1): e2301162, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37821415

RESUMO

Solid-state lithium batteries (SSLBs) have great development prospects in high-security new energy fields, but face major challenges such as poor charge transfer kinetics, high interface impedance, and unsatisfactory cycle stability. Defect engineering is an effective method to regulate the composition and structure of electrodes and electrolytes, which plays a crucial role in dominating physical and electrochemical performance. It is necessary to summarize the recent advances regarding defect engineering in SSLBs and analyze the mechanism, thus inspiring future work. This review systematically summarizes the role of defects in providing storage sites/active sites, promoting ion diffusion and charge transport of electrodes, and improving structural stability and ionic conductivity of solid-state electrolytes. The defects greatly affect the electronic structure, chemical bond strength and charge transport process of the electrodes and solid-state electrolytes to determine their electrochemical performance and stability. Then, this review presents common defect fabrication methods and the specific role mechanism of defects in electrodes and solid-state electrolytes. At last, challenges and perspectives of defect strategies in high-performance SSLBs are proposed to guide future research.

14.
Micromachines (Basel) ; 14(12)2023 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-38138322

RESUMO

Thin film technology of lithium-ion solid electrolytes should be developed for the creation of all-solid-state power sources. Solid electrolytes of the Li7La3Zr2O12 (LLZ) family are one of the promising membranes for all-solid-state batteries. LLZ films were obtained by electrophoretic deposition on Ti, Ni and steel substrates. The influence of different metal substrates on microstructure, phase composition and conductivity of the LLZ films after their heat treatment was studied. It was shown that the annealing of dried LLZ films in an Ar atmosphere leads to the transition from tetragonal modification to a low-temperature cubic structure. It was established that an impurity phase (Li2CO3) was not observed for LLZ films deposited on Ti foil after heat treatment, in contrast to films deposited on Ni and steel substrates. The highest lithium-ion conductivity values were achieved for the LLZ films annealed at 300 °C, 1.1 × 10-8 S cm-1 (at 100 °C) and 1.0 × 10-6 S cm-1 (at 200 °C).

15.
ACS Nano ; 17(22): 22196-22226, 2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-37934794

RESUMO

The cellulose industry depends heavily on water owing to the hydrophilic nature of cellulose fibrils and its potential for sustainable and innovative production methods. The emergence of nanocellulose, with its excellent properties, and the incorporation of nanomaterials have garnered significant attention. At the nanoscale level, nanocellulose offers a higher exposure of hydroxyl groups, making it more intimate with water than micro- and macroscale cellulose fibers. Gaining a deeper understanding of the interaction between nanocellulose and water holds the potential to reduce production costs and provide valuable insights into designing functional nanocellulose-based materials. In this review, water molecules interacting with nanocellulose are classified into free water (FW) and bound water (BW), based on their interaction forces with surface hydroxyls and their mobility in different states. In addition, the water-holding capacity of cellulosic materials and various water detection methods are also discussed. The review also examines water-utilization and water-removal methods in the fabrication, dispersion, and transport of nanocellulose, aiming to elucidate the challenges and tradeoffs in these processes while minimizing energy and time costs. Furthermore, the influence of water on nanocellulose properties, including mechanical properties, ion conductivity, and biodegradability, are discussed. Finally, we provide our perspective on the challenges and opportunities in developing nanocellulose and its interplay with water.

16.
ACS Appl Bio Mater ; 6(12): 5442-5457, 2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-37997919

RESUMO

Molecular self-assembly assisted self-healing supramolecular metallogels of azelaic acid with cobalt(II)-, nickel(II)-, and zinc(II)-based metal acetate salts were successfully fabricated. Individually, N,N'-dimethylformamide and dimethyl sulfoxide were immobilized within these distinctly synthesized soft-scaffolds of metallogels to attain their semisolid viscoelastic nature. Rheological experiments such as amplitude sweep, frequency sweep, and thixotropic measurements were executed for these metallogels to ratify their gel features. The different extents of supramolecular interactions operating within these solvent-directed metallogels were clearly reflected in terms of their distinct morphological patterns as investigated through field emission scanning electron microscopy. Comparative infrared (IR) spectral properties of metallogels along with individual metal salts and azelaic acid were analyzed. These experimental data clearly depict the significant shifting of Fourier transform (FT)-IR peaks of xerogel samples of different metallogels from the gel-forming precursors. The networks present within the soft-scaffold are evidently illustrated by the electrospray ionization-mass experimental data. The temperature-dependent ionic conductivity studies with these solvent-directed versatile metallogel systems were investigated through impedance spectroscopy. The temperature-dependent impedance spectroscopic studies clearly demonstrate that the ion-transportation within the gel matrix depends not only on the types of cations but also on the dielectric properties of the immobilized solvents. The antipathogenic effect of these metallogel systems has also been explored by testing their effectiveness against human pathogenic Gram-negative bacteria Klebsiella pneumoniae (MTCC 109) and Vibrio parahemolyticus, and Gram-positive bacteria like Bacillus cereus (MTCC 1272). These gel soft-scaffolds show no significant cytotoxicity against both the human neuroblastoma cell line-SH-SY5Y and the human embryonic kidney cell line-HEK 293.


Assuntos
Neuroblastoma , Sais , Humanos , Solventes , Temperatura , Células HEK293 , Antibacterianos/farmacologia , Zinco/farmacologia
17.
Int J Mol Sci ; 24(16)2023 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-37629085

RESUMO

The development of solid electrolytes with high conductivity is one of the key factors in the creation of new power-generation sources. Lithium-ion solid electrolytes based on Li7La3Zr2O12 (LLZ) with a garnet structure are in great demand for all-solid-state battery production. Li7La3Zr2O12 has two structural modifications: tetragonal (I41/acd) and cubic (Ia3d). A doping strategy is proposed for the stabilization of highly conductive cubic Li7La3Zr2O12. The structure features, density, and microstructure of the ceramic membrane are caused by the doping strategy and synthesis method of the solid electrolyte. The influence of different dopants on the stabilization of the cubic phase and conductivity improvement of solid electrolytes based on Li7La3Zr2O12 is discussed in the presented review. For mono-doping, the highest values of lithium-ion conductivity (~10-3 S/cm at room temperature) are achieved for solid electrolytes with the partial substitution of Li+ by Ga3+, and Zr4+ by Te6+. Moreover, the positive effect of double elements doping on the Zr site in Li7La3Zr2O12 is established. There is an increase in the popularity of dual- and multi-doping on several Li7La3Zr2O12 sublattices. Such a strategy leads not only to lithium-ion conductivity improvement but also to the reduction of annealing temperature and the amount of some high-cost dopant. Al and Ga proved to be effective co-doping elements for the simultaneous substitution in Li/Zr and Li/La sublattices of Li7La3Zr2O12 for improving the lithium-ion conductivity of solid electrolytes.


Assuntos
Eletrólitos , Lítio , Íons , Cerâmica , Cobalto
18.
J Colloid Interface Sci ; 647: 456-466, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37271090

RESUMO

In this work, the fabrication of strengthened triple network hydrogels was successfully achieved based on in-situ polymerization of polyacrylamide by combining both chemical and physical cross-linking methods. The ion conductive phase of lithium chloride (LiCl) and solvent in the hydrogel were regulated through soaking solution. The pressure and temperature sensing behavior and durability of the hydrogel were investigated. The hydrogel containing 1 mol/L LiCl and 30 %v/v glycerol displayed a pressure sensitivity of 4.16 kPa-1 and a temperature sensitivity of 2.04 %/oC ranging from 20 to 50 °C. The durability results reveal that the hydrogel could maintain water retention rate of 69 % after 20 days of ageing. The presence of LiCl disrupted the interactions among water molecules and made it possible for the hydrogel to respond to changes in environment humidity. The dual signal testing revealed that the delay of temperature response over time (about 100 s) is much different from the rapidity of pressure response (in 0.5 s). This leads to the obvious separation of the temperature-pressure dual signal output. The assembled hydrogel sensor was further applied to monitor human motion and skin temperature. The signals can be distinguished by different resistance variation values and curve shapes in the typical temperature-pressure dual signal performance of human breathing. This demonstrates that this ion conductive hydrogel has the potential for application in flexible sensors and human-machine interfaces.

19.
Membranes (Basel) ; 13(5)2023 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-37233529

RESUMO

In the presented study, films from tetragonal Li7La3Zr2O12 were obtained by electrophoretic deposition (EPD) for the first time. To obtain a continuous and homogeneous coating on Ni and Ti substrates, iodine was added to the Li7La3Zr2O12 suspension. The EPD regime was developed to carry out the stable process of deposition. The influence of annealing temperature on phase composition, microstructure, and conductivity of membranes obtained was studied. It was established that the phase transition from tetragonal to low-temperature cubic modification of solid electrolyte was observed after its heat treatment at 400 °C. This phase transition was also confirmed by high-temperature X-ray diffraction analysis of Li7La3Zr2O12 powder. Increasing the annealing temperature leads to the formation of additional phases in the form of fibers and their growth from 32 (dried film) to 104 µm (annealed at 500 °C). The formation of this phase occurred due to the chemical reaction of Li7La3Zr2O12 films obtained by electrophoretic deposition with air components during heat treatment. The total conductivity of Li7La3Zr2O12 films obtained has values of ~10-10 and ~10-7 S cm-1 at 100 and 200 °C, respectively. The method of EPD can be used to obtain solid electrolyte membranes based on Li7La3Zr2O12 for all-solid-state batteries.

20.
Chemistry ; 29(43): e202301012, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37173870

RESUMO

Over the past few decades, stimuli-responsive materials have been widely applied to porous surfaces. Permeability and conductivity control of ions confined in nanochannels modified with stimuli-responsive materials, however, have been less investigated. In this work, the permeability and conductivity control of ions confined in nanochannels of anodic aluminum oxide (AAO) templates modified with thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes are demonstrated. By surface-initiated atom transfer radical polymerization (SI-ATRP), PNIPAM brushes are successfully grafted onto the hexagonally packed cylindrical nanopores of AAO templates. The surface hydrophilicities of the membranes can be reversibly altered because of the lower critical solution temperature (LCST) behavior of the PNIPAM polymer brushes. From electrochemical impedance spectroscopy (EIS) analysis, the temperature-gating behaviors of the AAO-g-PNIPAM membranes exhibit larger impedance changes than those of the pure AAO membranes at higher temperatures because of the aggregation of the grafted PNIPAM chains. The reversible surface properties caused by the extended and collapsed states of the polymer chains are also demonstrated by dye release tests. The smart thermo-gated and ion-controlled nanoporous membranes are suitable for future smart membrane applications.

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