Ionomer Research Articles

Three-layer ionic polymer–metal composite actuator with functionalized carbon nanotubes incorporated into Nafion

Three-layer ionic polymer–metal composite actuator with functionalized carbon nanotubes incorporated into Nafion

High-performance ionic polymer actuators with Triple-layered multifunctional electrodes

Ionic polymer actuators have attracted attention in recent years due to their remarkably large strain under low-voltage stimulation. However, a key challenge for fabricating high-performance ionic polymer actuators is to develop a firm electrode with high electrical conductivity and electrochemical performance. Herein, inspired by the structure of zoysia grass, we proposed an efficient method to prepare the triple-layered multifunctional electrodes capable of low surface resistance (∼3.4 Ω/□), high adhesion (∼328 KPa) and good electrochemical performance for ionic polymer actuators. Through the spraying and impregnation-electroplating (IEP), three functional layers of multifunctional electrodes are obtained, including MWCNTs/Nafion interfacial layer, Ag NWs fixed layer and Ag NWs@Au layer, which respectively contribute to the charge storage in the electrode, high strength and the uniform and fast charge distribution. The synergic effect of these three functional layers maintains a high stability of multifunctional electrodes after being immersed in DI water for 7 days or 1500 bending cycles, and greatly enhances the actuation performance of ionic polymer actuators, resulting in an extreme bending deformation (increasing by 460%). This work represents an important step towards ionic polymer actuators where the synergic effect in electrodes plays an important role in promoting electrochemical actuation performance.

A Multiple-Responsive Fluorescence Probe Based on Water-Soluble Fluorescent Conjugated Polymer for Biomolecules Detection

In this paper, we designed a multiresponsive fluorescent probe based on a synthetic water-soluble conjugated fluorescent polymer (PF-DBT-S-S-PDI) consisting of the conjugated fluorescent backbones and the hydrophilic side chains connected by a disulfide bond. Based on its specific structures, according to two different response mechanisms of fluorescence resonance energy transfer (FRET) and heavy atom effect, the polymer shows high sensitivity and selectivity toward reductive species-thiols and oxidizing substances (such as H2O2) in different ways. Owing to the presence of disulfide bonds, the reductive mercaptan in the solution would cause the water-soluble branches in the micellar structure to break off and leave, which causes the hydrophobic framework of the polymer to aggregate and enhance the fluorescence intensity. On the other hand, because the PDIs in branches are ionic polymers with many iodide ions, H2O2 in solution oxidizes iodide ions into iodide so that the heavy atomic effect of iodide would quench the fluorescence. Both mechanisms have high sensitivity; e.g., the detection limits for mercaptan (such as cysteine) were 0.052 mM, 5.26 μM for H2O2, and 1.06 μM for glucose (combined with oxidase). The multiple detection ability of the polymer has been validated by evaluating free thiols and glucose levels in food samples and tissue homogenates. Our work provided a strategy for integrating multiple species detection capabilities on a single probe.

Toughening Ionic Polymer Using Bulky Alkylammonium Counterions and Comb Architecture.

Ionic interactions in ionic polymers, such as ionomers, polyelectrolytes, and polyampholytes, contribute to toughness in systems with high mobility and active ion dynamics, such as hydrogels and elastomers. However, it remains challenging to toughen rigid polymers through ionic interactions without lowering their elastic modulus through plasticization. Here, we present a strategy for toughening without sacrificing the elastic modulus by combining a comb polymer with bulky ammonium counterions. We designed and synthesized ionic comb polymers with oligoethylene glycol side chains and carboxylic acids in each monomer unit of the polynorbornene backbone, neutralized by trialkylamines, ranging from ethyl to octyl. The counterion size in ionic comb polymers influenced the mechanical properties of tensile testing─not the elongation at break and the elastic modulus but the ultimate strength and toughness. The ionic comb polymer containing heptylammonium counterions displayed the highest toughness of 77 MJ m-3. Tensile studies at various strain rates demonstrated a rate-dependent difference between heptyl- and octylammonium counterions. This result suggests that the heptylammonium counterion acted as a sacrificial bond by providing a moderate dissociation rate that was slightly slower than that of the octylammonium counterion, leading to toughening.

Silver(I) Coordination Polymer Ligated by Bipyrazole Me4bpzH2, [Ag(X)(Me4bpzH2)] (X = CF3CO2− and CF3SO3−, Me4bpzH2 = 3,3′,5,5′-Tetramethyl-4,4′-bipyrazole): Anion Dependent Structures and Photoluminescence Properties

Coordination polymers of transition metal ions are fascinating and important to coordination chemistry. One of the ligands known to form particularly interesting coordination polymers is 3,3',5,5'-tetramethyl-4,4'-bipyrazole (Me4bpzH2). Group 11 metal(I) ion coordination polymers, other than those of copper(I), are relatively easy to handle because of their low reactivity towards dioxygen and moisture. However, the known silver(I) coordination polymers often have poor solubility in common solvents and so cannot be easily analyzed in solution. By using a tetramethyl substituted bipyrazole ligand, we have synthesized more soluble silver(I) complexes that contain the trifluoromethyl group in the coordinated ions CF3CO2- and CF3SO3- in [Ag(CF3CO2)(Me4bpzH2)] and [Ag(CF3SO3)(Me4bpzH2)]. We determined both structures by single-crystal X-ray analysis at low temperatures and compared them in detail. Moreover, we investigated the solution behavior of these coordination polymers by 1H-NMR, IR, Raman, UV-Vis spectroscopies, and their low-temperature, solid-state photoluminescence. The high-energy band at ~330 nm corresponded to ligand-centered (bipyrazole) fluorescence, and the low-energy band at ~400 nm to ligand-centered phosphorescence resulting from the heavy atom effect.

Forced Interactions: Ionic Polymers at Charged Surfactant Interfaces.

Characterizing electrostatic interactions at heterogeneous interfaces is critical for developing a fundamental description of the dynamic processes at charged interfaces. Water-in-oil reverse micelles (RMs) offer a high degree of tunability across composition, polarity, and temperature, making them ideal systems for studying interactions at heterogeneous liquid-liquid interfaces. In the present study, we use a combination of ultrafast two-dimensional infrared spectroscopy and molecular dynamics (MD) simulations to determine the picosecond interfacial dynamics in RMs containing binary compositions of sorbitan monostearate and anionic or cationic cosurfactants, which are used to tune the ratio of charged to nonionic surfactants at the interface. The positively charged polyethylenimine (PEI) polymer is encapsulated within the RMs, and the carbonyl stretching mode of sorbitan monostearate reports on the interfacial hydrogen-bond populations and dynamics. The results show that hydrogen-bond populations are altered through the inclusion of both negatively and positively charged cosurfactants. Charged surfactants increase interfacial water penetration into the surfactant layer, and the surface localization of polymers decreases water penetration. Local hydrogen-bond dynamics undergo a slowdown with the inclusion of charged surfactants, and the encapsulation of polymers results in similar effects, irrespective of the charge.

Ho-Ion-Polymer/Graphene Heterojunctions Toward Room-Temperature Ferromagnets.

Organic ferromagnetic materials offer great promise for spintronic devices, carbon-based chips, and quantum communications, but remain as a challenging issue due to their low saturation magnetization and/or unsustainable ferromagnetic properties. To date, magnetic ion polymers have displayed paramagnetism without exception at room-temperature. In this study, it is reported for the first time that, owing to the structural restriction and charge exchange of Ho ion by polymer/graphene π-π stacking heterojunctions, holmium ion polymer composites exhibited typical hysteresis lines of ferromagnetic materials at room temperature. The room-temperature ferromagnetic ion polymer composite presented the highest saturation magnetization value of 3.36 emu g-1 and unprecedented sustainable ferromagnetism, compared to reported room-temperature organic ferromagnetic materials. Accordingly, prepared ferromagnetic composites also achieved impressive wave absorption properties, with a maximum reflection loss of as much as -57.32dB and a broad absorption bandwidth of 5.05GHz. These findings may promote the development of room-temperature organic ferromagnetic materials.

Ultra-long-life and ultrathin quasi-solid electrolytes fabricated by solvent-free technology for safe lithium metal batteries

The excessive consumption of organic solvent and enhancement of environmental protection protocols necessitate the exploitation of desirable approach to handle our solid-state electrolytes. Herein, we report an all solvent-free method for the preparation of low-cost, recyclability, flexible, ultrathin, and high ionic conductivity quasi-solid polymer electrolytes (QPE) membrane, which is an 5 μm-thick PE separators filled with polyether-block-polyamide (PEO-b-PA6)/LiTFSI/tetraethylene glycol dimethyl ether (TEGDME) (PPLT) that can be used as a safe lithium metal batteries. The self-fusion characteristics of the PEO-b-PA6 with supramolecular hydrogen bonds guarantees the intimate and perfect interfaces even during extreme deformations and crack of the solvent-free machining process. The ultrathin PE separators is mechanically strong, preventing batteries from short-circuiting even after more than 1200 h of cycling, and the ionic conductivity of PPLT reaches up to 1.02 × 10−4 S cm−1 at 30 ℃ by adding only 25 wt% of TEGDME as plasticizer. The LFP//Li cells using PPLT as electrolyte exhibits excellent reversible capacity of 116 mAh g−1 at 1 C after 700 cycles at 28 °C. In addition, the polymer soft-pack batteries using PPLT achieve highly reversible capacity of 124.9 mAh g−1 after 200 cycles at 0.2 C. It is noted that this solvent-free film-making process and outstanding electrochemical performance of this QPE could be further delivered to other room temperature rechargeable solid-state lithium metal batteries and enlighten safe, low-carbon green and high-energy solid-state batteries.

Effect of ionic liquids on the performance of dye-sensitized solar cells using poly(vinyl alcohol)/ polypyrrole based polymer electrolytes

ABSTRACT A novel quasi-solid-state polymer electrolyte was prepared using poly(vinyl alcohol)-polypyrrole, potassium iodide, iodine, and ethylene carbonate mixed with two types of ionic liquids, 1-methyl-3-propylimidazolium iodide (MPII) and 1-ethyl-3-methylimidazolium iodide (EMII). The prepared polymer electrolyte was structurally characterized by FTIR spectroscopy. The lowest degree of crystallinity and activation energy were found in the MPII-incorporated polymer electrolytes. Higher values of dislocation density and microstrain are obtained for ionic liquid-incorporated polymer electrolytes. The lowest value of series resistance was observed in MPII-based polymer electrolyte and thereby the conduction was increased. The average roughness of the MPII-based polymer electrolyte at 17.901 nm was strongly dependent on the influence of the MPII content. The dye-sensitized solar cells (DSSC) built with MPII-based polymer electrolytes have achieved the highest photo-conversion efficiency of 4.51% under 100mWcm−2 illumination.

A Study on the Synthesis and Proton Transport Behavior of Multilayered ZSM-5 Zeolite Nanosheet Membranes Laminated on Polymer Substrates

Single crystalline ZSM-5 ZNs with thicknesses around 6 nm were obtained by secondary growth of silicalite nanoparticles using diquaternary bis-1,5(tripropyl ammonium) pentamethylene diiodide (dC5) as a structure-directing agent (SDA). The dC5 could be effectively removed from the ZN pores by either high-temperature calcination or UV irradiation in air at room temperature but not by the piranha solution treatment. Ultrathin ZN-laminated membranes (ZNLMs) were fabricated by sandwiching a UV-activated multilayered ZN film between two recast Nafion® layers (ZNLM-Nafion) and by filtration coating from a suspension of thermally activated ZNs on a nonionic porous PVDF (ZNLM-PVDF). The ZNLMs on both supports demonstrated the ability of highly proton-selective ion conduction with low resistances in aqueous electrolyte solutions. The ZNLM-PVDF with PVDF binder was structurally stable, and it achieved a comparably low ASR but much higher proton selectivity compared with a Nafion membrane of same overall thickness. However, detachment between the ZNLM and Nafion layers occurred when the ZNLM-Nafion operated in aqueous electrolyte solutions. Results of this study show the potential for developing ZNLMs as efficient proton-conducting membranes without using expensive ionic polymer matrices. However, the development of polymer-supported ZNLMs is hindered by the current inefficiency in preparing well-dispersed suspensions of open-pore ZNs. Future development of efficient methods for synthesizing open-pore ZNs in dispersed states is key to realizing high-performance ZNLMs on polymers.

Ultrasensitive Ionic Liquid Polymer Composites with a Convex and Wrinkled Microstructure and Their Application as Wearable Pressure Sensors.

The development of pressure sensors with high sensitivity and effectiveness that exhibit linearity over a wide pressure range is crucial for wearable devices. In this study, we fabricated a novel ionic liquid (IL)/polymer composite with a convex and randomly wrinkled microstructure in a cost-effective and facile manner using an opaque glass and stretched polydimethylsiloxane template. The fabricated IL/polymer composite was used as the dielectric layer in a capacitive pressure sensor. The sensor exhibited a high linear sensitivity of 56.91 kPa-1 owing to the high interfacial capacitance formed by the electrical double layer of the IL/polymer composite over a relatively wide range (0-80 kPa). We also demonstrated the sensor performance for various applications such as a glove-attached sensor, sensor array, respiration monitoring mask, human pulse, blood pressure measurement, human motion detection, and a wide range of pressure sensing. It would be expected that the proposed pressure sensor has sufficient potential for use in wearable devices.

Adulteration of Milk Identification Using Ionic Polymer Metal Composite as Sensor

Milk adulteration is found as one of the social problems throughout the globe. Consumption of adulterated milk causes various diseases in humans and great concern to the food industry. Adulteration is generally done by adding chemicals to the milk, especially water. Inappropriately, milk is being very easily adulterated throughout the world and significantly worse in developing and underdeveloped countries due to the absence of adequate monitoring and lack of proper law implementation. The international and national research surveys presented the use of various electrochemical, nanomaterial, and thermal sensing mechanisms for the detection of adulteration in milk (example: spectroscopic methods, thermal sensors, chitosan-multiwalled carbon nanotubes, etc.). However, the ionic polymer metal composite (IPMC) is used as a sensor or actuator; for this application, IPMC is explored as a sensor for detecting the impurities in milk. IPMC used in this experiment is Nafion base, which is a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. In this letter, the authors took the opportunity to use the electroactive polymer material IPMC as a taste sensor.

Flexible sugarcane juice based ionic polymer membrane

Flexible sugarcane juice based ionic polymer membrane

Magnetically-separable quasi-homogeneous catalyst: Brush-type ionic liquid polymer coated magnetic polymer microspheres for tandem reactions to produce 4H-pyrans/biodiesel

Employing magnetic polystyrene microspheres as the core and brush-type alkaline imidazolium ionic liquid polymers as the covalent bonds, a robust magnetically-separable quasi-homogeneous magnetic brush-type ionic liquid polymers ([Im][OH]/MP-B) was synthesized. Due to the features of brush-type ionic liquid polymer (BILPs), [Im][OH]/MP-B demonstrated high catalytic activity. With a broad variety of substrates, [Im][OH]/MP-B was applied in Knoevenagel-Michael tandem reactions for the synthesis of 4 H-pyrans (achieving 99.99% conversion and 93.6% yield) and transesterification tandem reactions for sustainable biodiesel production (achieving 99.9% conversion and 95.2% yield). Furthermore, the catalytic performance of [Im][OH]/MP-B was superior to that of [Im][OH]/MP-CL and [Im][OH]/MP-L and comparable with that of homogeneous catalysts. The reasonable and feasible reaction mechanism of magnetic ionic liquid polymers catalyzing tandem reactions was explored in-depth based on the catalytic performance and kinetics, which clearly demonstrated the catalytic activity and stability of [Im][OH]/MP-B. Notably, [Im][OH]/MP-B was effortlessly recovered by magnetic separation and reutilized numerous times with no evident change in catalytic performance, composition, or microstructure, indicating promising possibilities for ecologically friendly procedures. This work provides a potential strategy for the synthesis of magnetic BILPs for tandem reactions, which could serve as a platform for ecologically friendly and sustainable chemistry.

Hollow Carbon Nanopillar Arrays Encapsulated with Pd-Cu Alloy Nanoparticles for the Oxygen Evolution Reaction.

Delicate design and bottom-up synthesis of hollow nanostructures for oxygen evolution electrocatalysts is a promising way to accelerate the reaction kinetics of overall water splitting. Herein, an efficient and versatile strategy for the controllable preparation of Pd-Cu alloy nanoparticles encapsulated in carbon nanopillar arrays (PD-Cu@HPCN) is developed. Core-shell structured MOF@imidazolium-based ionic polymers (ImIPs) have been prepared and adopted as a template, along with the decomposition of the inner Cu-MOFs when an anion exchange occurs between sodium tetrachloropalladate in solution and bromides in the external ImIP shell. Pd nanoparticles will be highly dispersed in the resulting Pd-Cu@HO-ImIP array, and subsequent topotactic transformation generates Pd-Cu@HNPC. No hazardous reagents or tedious steps are used to remove the inner Cu-MOF templates in contrast to the traditional top-down methods. Remarkably, the Pd-Cu@HPCN catalyst possesses outstanding oxygen evolution reaction (OER) activity, including small overpotential with 10 mA cm-2 at an overpotential of 188 mV, a large double layer capacitance (73.8 mF cm-2), and high stability (20 h). This simple, green, and efficient synthesis methodology represents a new way to design metal alloys for OER electrocatalysts or other electrocatalytic devices.

Perylene Diimide-Containing Dynamic Hyper-crosslinked Ionic Porous Organic Polymers: Modulation of Assembly and Gas Storage

A strategy to synthesize hyper-crosslinked polymers with strong visible-light absorption and abundant ionic sites is discussed. This is achieved in a one-pot reaction via the simultaneous Friedel–Crafts alkylation and quaternization reaction between α,α′-dibromo-p-xylene (DBX) and perylene diimide (PDI) substituted with N,N-dimethyl ethylene to result in hyper-crosslinked ionic polymers (HIPs). These HIPs display good surface areas with strong visible-light absorption (400–650 nm) and dispersibility in polar solvents like water and DMSO. Importantly, our experimental and theoretical studies indicate that PDI-HIPs possess a dynamic network with good uptake of water up to seven times their weight. Notably, PDI in PDI-HIPs is not only responsible for visible-light absorption but also acts as a probe to study their dynamic nature. Moreover, the presence of ultramicropores and CO2-philic functional groups in PDI-HIPs renders good CO2 uptake up to 2.11 mmol/g at 273 K despite their relatively low surface area.

Electrochemo-poromechanics of Ionic Polymer Metal Composites: Towards the Accurate Finite Element Modelling of Actuation and Sensing

Ionic polymer metal composites (IPMCs) consist of an electroactive polymeric membrane, which is plated with metal electrodes and includes a fluid phase of ions in a solvent, whose diffusion allows for actuation and sensing applications. We build on a previous finite-deformation theory of our group that accounts for the cross-diffusion of ions and solvent and couples the mass balances of these species with the stress balance and the Gauss law. Here, we abandon the assumption that the fluid phase is a dilute solution, with benefits on both modelling and computation. A reliable finite element (FE) implementation of electrochemomechanical theories for IPMCs is challenging because the IPMC behaviour is governed by boundary layers (BLs) occurring in tiny membrane regions adjacent to the electrodes, where steep gradients of species concentrations occur. We address this issue by adopting the generalized FE method to discretise the BLs. This allows unprecedented analyses of the IPMC behaviour since it becomes possible to explore it under external actions consistent with applications, beside obtaining accurate predictions with a reasonable computational cost. Hence, we provide novel results concerning the influence of the membrane permittivity on the species profiles at the BLs. Additionally, by leveraging on the mobility matrix, we establish that the initial peak deflection in actuation strongly depends on the constitutive equations for the species transport and discuss the predictions of some experimental results from the literature. Overall, we demonstrate the potential of the proposed model to be an effective tool for the thorough analysis and design of IPMCs.

Engineering the Pore Structure and Functionality of Ionic Porous Polymers for Separating Acetylene over Carbon Dioxide

AbstractPrecise engineering of organic porous polymers to realize the selective separation of structurally similar gases presents a great challenge. In this study, a new class of ionic porous polymers P(Ph3Im‐Br‐nDVB) with a high ionic density and microporous surface area are constructed through a facile copolymerization strategy, providing an efficient path to rational control over pore structure and functionality. The first example of ionic porous organic polymers is reported to address the challenge of discriminating the subtle difference of C2H2 and CO2, which have almost identical molecular sizes and similar physicochemical properties, which achieve the highest C2H2/CO2 selectivity (17.9) among porous organic polymers. These ionic porous polymers exhibit high stability and excellent dynamic breakthrough performance for binary C2H2/CO2 mixtures, indicating their practical feasibility. Modeling studies reveal that anions are the specific binding sites for preferential C2H2 capture because of Br−···HCCH interactions. This study not only demonstrates an efficient strategy to build novel ionic porous polymers integrating abundant micropores and ionic sites but also sheds some light on the development of functionalized materials for the separation of structurally similar gas molecules.

A Flexible Solid-State Ionic Polymer Electrolyte for Application in Aluminum Batteries

Rechargeable aluminum batteries are promising candidates for post-lithium energy storage systems. The electrolyte system of rechargeable aluminum batteries is an urgent research topic hindering the deployment in large-scale applications. To solve the critical problems of current ionic liquid electrolytes, such as leakage, corrosivity, and the need for using separators, we developed a freestanding ionic polymer electrolyte using the direct complexation of polyamide 6 (PA6) with aluminum chloride (AlCl3) and the organic salt triethylamine hydrochloride (Et3NHCl). This complexation allows a dissolution of up to 20 wt % of PA6 in the sample to achieve outstanding mechanical strength and stable electrode–electrolyte interfaces without loss of electrolyte properties. The mechanical and electrochemical properties of the polymer were studied and correlated to the complexation mechanism, which was investigated by FTIR spectroscopy. The ionic polymer electrolyte allows the elimination of unfavorable separators and achieves a high ionic conductivity up to 0.3 mS cm–1 and is capable of electrochemical stripping/plating of aluminum. An Al/graphite battery using this electrolyte provides excellent cycling performance. In addition, the nonflowing ionic polymer electrolyte eliminates the corrosion caused by electrolyte leakage in aluminum batteries and enables the use of conventional stainless steel housings. Our results indicate that this type of solid-state ionic polymer is a promising strategy for achieving stable and safe, yet flexible aluminum batteries.

Improved ionic and mechanical properties of ion-exchange membrane with an ionic silica network for high-performance ionic polymer-metal composites

Ion-exchange membranes considerably affect the actuation of ionic polymer–metal composites (IPMCs) through ion movement under an applied voltage. To enhance the performances of IPMCs, previous studies have increased the ionic content of the ion-exchange membrane, thereby improving its ionic conductivity and water uptake. Although this increased ionic content enhances IPMC displacement, the increased water uptake diminishes IPMC stiffness, resulting in decreased IPMC blocking force. Therefore, a new approach is needed to resolve the trade-off between displacement and force. Here, we reinforced the Nafion membrane by forming a sulfonated polysilsesquioxane structure inside. The incorporation of this ionic silica network increased the total ion content of the membrane and included silica as a mechanically reinforcing filler. The force of the IPMC can be enhanced despite increased water uptake by the membrane. Therefore, IPMCs were obtained with improvements in displacement and blocking force. Comparison of the IPMCs with commercial Nafion films revealed similar displacement and superior force, demonstrating their applicability. These findings represent a breakthrough in enhancing the actuation of IPMCs while resolving the trade-off between displacement and force.