Microphase Separation Research Articles

The antibacterial and antialgal enhancement of the hydroquinone acrylamide polyurethane coating based on microphase separation

The undesirable and inevitable adhesion of marine organisms on submerged surfaces has seriously affect the environment, economy and society, so emerging and promising strategies for antifouling are required. Here, the novel and environmental strategy of the antibacterial and antialgal materials was proposed for the application of the antifouling coating without releasing harmful substances. The environment-friendly antifouling agent, the capsaicin derivative N-(2,5-dihydroxy-4-acrylamide meth-ylbenzyl)acrylamide (PHABA), was modified to the molecular chain of the polyurethane. The best tensile strength was up to 23.5 MPa of PUP-25% and the elongation at break was 415% of PUP-25%. The excellent wear resistance (300 wear cycles) and chemical solution resistance (H2SO4, NaOH, and NaCl solutions) revealed the applicability of the coating. PHABA would migrate to the surface of the polyurethane coating with time and enhanced the antibacterial and antialgal properties of the coating. PUP-25% prevented more than 90% of bacterial and algal adhesion, indicating the potential application of the antifouling coating.

PEG-crosslinked O-carboxymethyl chitosan films with degradability and antibacterial activity for food packaging

This study developed a kind of PEG-crosslinked O-carboxymethyl chitosan (O-CMC–PEG) with various PEG content for food packaging. The crosslinking agent of isocyanate-terminated PEG was firstly synthesized by a simple condensation reaction between PEG and excess diisocyanate, then the crosslink between O-carboxymethyl chitosan (O-CMC) and crosslinking agent occurred under mild conditions to produce O-CMC–PEG with a crosslinked structure linked by urea bonds. FT-IR and 1H NMR techniques were utilized to confirm the chemical structures of the crosslinking agent and O-CMC–PEGs. Extensive research was conducted to investigate the impact of the PEG content (or crosslinking degree) on the physicochemical characteristics of the casted O-CMC–PEG films. The results illuminated that crosslinking and components compatibility could improve their tensile features and water vapor barrier performance, while high PEG content played the inverse effects due to the microphase separation between PEG and O-CMC segments. The in vitro degradation rate and water sensitivity primarily depended on the crosslinking degree in comparison with the PEG content. Furthermore, caused by the remaining –NH2 groups of O-CMC, the films demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus. When the PEG content was 6% (medium crosslinking degree), the prepared O-CMC–PEG−6% film possessed optimal tensile features, high water resistance, appropriate degradation rate, low water vapor transmission rate and fine broad-spectrum antibacterial capacity, manifesting a great potential for application in food packaging to extend the shelf life.

A Strong and Highly Transparent Ionogel Electrolyte Enabled by In Situ Polymerization-Induced Microphase Separation for High-Performance Electrochromic Devices.

Electrochromic devices built with ionogel electrolytes are seen as a pivotal step toward the future of quasi-solid electrochromic devices, due to their striking properties like exceptional safety and high ionic conductivity. Yet, the poor mechanical strength of electrolyte of these devices remains a constraint that hampers their advancement. As a resolution, this research explores the use of a robust, transparent ionogel electrolyte, which is designed using an in situ microphase separation strategy. The ionogels are highly transparent and robust and exhibit excellent physicochemical stability, including a wide electrochemical window and high temperature tolerance. Benefitting from these properties, a high-performance electrochromic device is fabricated through in situ polymerization with the ionogels, PPRODOT as the electrochromic layer, and PEDOT: PSS as the ion storage layer, achieving high transmittance contrast (43.1%), fast response (1/1.7 s), high coloring efficiency (1296.4 cm2 C-1), and excellent cycling endurance (>99.9% retention after 2000 cycles). In addition, using ITO-poly(ethylene terephthalate) as flexible substrates, a deformable electrochromic device displaying high stability is realized, highlighting the potential use in functional wearables.

Dendronized polyurethanes showing improved mechanical properties and unprecedent thermoresponsiveness

Introduction of topological structures to polyurethanes (PUs) may impart them with different microphase separation, which would be beneficial to afford them novel properties and expand their applications. Herein, a series of dendronized polyurethanes (DPUs) were synthesized with polyols carrying three-fold dendritic OEGs as the soft segment and either aliphatic or aromatic isocyanates as the hard segments. Different from conventional PUs with linear polyols as the soft segments, DPUs contain soft segments with spherical pendants, which may contribute different phase separation. In addition, dendritic OEGs afford DPUs with excellent thermoresponsiveness. Films from aliphatic DPUs and those from the mixture of aromatic DPU and linear PU were prepared. These thermoresponsive DPU films show tunable regulation capacity for encapsulated guests during thermally-induced aggregation of the dendritic OEGs. Remarkably, the phase separations of DPUs were found to be closely related to the amount of dendritic OEGs, and the PU films exhibited excellent mechanical properties with suitable amount of dendritic OEGs as the soft segment. Therefore, dendronization of PUs not only can modulate their microphase separation, but also provides a unique approach to develop PUs materials with novel properties.

Flexible and rigid block copolymers from recyclable polyesters

The paper addresses a study on the thermoplastic elastomers (TPE) that can be synthesized using monomers retrieved from the chemically recycled semi-aromatic polyesters, such as terephthalic acid from low value stream recyclable polyethylene terephthalate (rPET). In contrast to PET, because of their physical and mechanical properties, TPEs are often used as an engineering polymer in automotive and consumer goods. The understanding of the crystallization and phase behavior of these materials is crucial to fine-tune the molecular structure and properties. We explore the interplay between the crystallization and phase separation in these materials by performing experiments on model thermoplastic elastomers consisting of polybutylene terephthalate (PBT) and polytetrahydrofuran (PTHF). A common denominator in the synthesis of PBT is terephthalic acid that can be obtained from Dimethyl Terephthalate (DMT) or recycling used PET. We show that by varying the compositions and block length of different blocks, in PBT-PTHF block copolymers, morphological variations from spherulites to dendrites can be induced, which could be captured using optical microscopy. By performing rheological and small angle X-ray scattering studies, we correlate these morphological variations at microscopic length scales, to the chain architecture at nanometer length scales. Our observations reveal that at the higher rigid PBT content, the process of phase separation strongly influences the crystallization kinetics that promotes the lamellar structure of the semi-crystalline polymer, observed at room temperature. On the other hand, in the presence of higher soft block content, the crystal growth occurs with minimal influence of the microphase separation. In broader generality, no morphological differences in the TPEs synthesized using the terephthalic acid from rPET are found. However, when the monomer from rPET is used, enhancement in crystallization rate occurs in the TPEs having similar molar mass and molecular configuration. We attribute the enhanced crystallization rate to the catalyst residues present in the terephthalic acid obtained fom rPET.

Poly(ethylene oxide)- and Polyzwitterion-Based Thermoplastic Elastomers for Solid Electrolytes.

In this article, ABA triblock copolymer (tri-BCP) thermoplastic elastomers with poly(ethylene oxide) (PEO) middle block and polyzwitterionic poly(4-vinylpyridine) propane-1-sulfonate (PVPS) outer blocks were synthesized. The PVPS-b-PEO-b-PVPS tri-BCPs were doped with lithium bis-(trifluoromethane-sulfonyl) imide (LiTFSI) and used as solid polyelectrolytes (SPEs). The thermal properties and microphase separation behavior of the tri-BCP/LiTFSI hybrids were studied. Small-angle X-ray scattering (SAXS) results revealed that all tri-BCPs formed asymmetric lamellar structures in the range of PVPS volume fractions from 12.9% to 26.1%. The microphase separation strength was enhanced with increasing the PVPS fraction (fPVPS) but was weakened as the doping ratio increased, which affected the thermal properties of the hybrids, such as melting temperature and glass transition temperature, to some extent. As compared with the PEO/LiTFSI hybrids, the PVPS-b-PEO-b-PVPS/LiTFSI hybrids could achieve both higher modulus and higher ionic conductivity, which were attributed to the physical crosslinking and the assistance in dissociation of Li+ ions by the PVPS blocks, respectively. On the basis of excellent electrical and mechanical performances, the PVPS-b-PEO-b-PVPS/LiTFSI hybrids can potentially be used as solid electrolytes in lithium-ion batteries.

Chitosan-derived large surface area porous carbon via microphase separation engineering of pore-regulation and nitrogen-doping coupling for high-performance supercapacitors

In the face of the contradiction between the shortage of fossil raw materials, global warming and growing energy demand, it is of great practical significance to apply biomass, which is widely available in nature, environmentally friendly and renewable, to energy storage. Based on the coupling mechanism of pore-regulation and N-doping, this study implements pre-carbonization through microphase separation engineering in the chitosan (CS) and aniline (AN) co-hydrothermal. Using hydrochar as the precursor, porous carbon with good electrochemical properties has been prepared by a multi-step process consisting of KOH activation, pyrolysis, pickling and water washing. The CS/AN co-doped porous carbons (1830.08–2576.53 m2/g) show an enhancement of 8.48%–52.73 % in specific surface area compared to the CS porous carbon (1687.02 m2/g). The hierarchical network structure of the micro-mesoporous interconnects enables fast ion transport and the ultra-micropores further increase the specific capacitance of the electrodes. Theoretical calculation shows that N doping can effectively activate the chemically inert carbon structure and enhance the adsorption capacity of electrolyte ions, thus increasing the specific capacitance. Using 6 M KOH as the electrolyte, CS-AN60-220-800 exhibits a specific capacitance of 368.6 F/g (1.0 A/g) in the three-electrode system. In the two-electrode system, the supercapacitor device constructed with CS-AN60-220-800 demonstrates a capacitance retention of 95.32 % (after 10,000 cycles) along with an energy density of 14.16 Wh/kg (with a power density of 125 W/kg), which is at a high level among similar biomass symmetric supercapacitors. The preparation strategy provides a valuable reference for the preparation of other biomass-based porous carbon, as well as for applications in energy storage.

The effect of polymer with tunable alkyl spacers on the microstructure of amphoteric membrane for vanadium redox flow battery (VRB)

Amphoteric membranes, as promising candidates for VRBs, have attracted more attention. The side-chain-type polymers go far towards improving ion exchange capacity and further enhancing ion conductivity. A kind of Amphoteric ion exchange membranes (AIEMs) with different alkyl chain lengths (C2, C6, and C12 spacers) were synthesized by using ring-opening metathesis polymerization (ROMP). In addition, the interactions between N-containing groups with positively charged and -SO3- groups prevent swelling and vanadium crossover. The microphase separation structure through side chain induction was regulated, to respond to the ionic mobility of the membrane. The effect of the spacer lengths on the ion selectivity of AIEMs is investigated. In addition, the size and matrix of the constructed ion channel were calculated by using coarse-grained molecular dynamics (CGMD) simulation, which further verified the experiment.

Interpenetrating polymer networks of polyurethane and polytriazole: Effect of the composition and number average molecular weight of glycidyl azide polymer on the mechanical properties and morphology

AbstractOn account of some special advantages of interpenetrating polymer networks (IPNs), the preparation of IPNs with excellent properties may be a promising way to strengthen the polyurethanes (PUs) and toughen the glycidyl azide polymer (GAP) based polytriazoles (PTAs). This work provides the effect of composition and number average molecular weight (Mn) of GAP on the mechanical properties and morphology of full‐IPNs. A series of IPNs based on the crosslinked Ace‐terminated GAP (Ace‐GAP) as polytriazole phase and crosslinked hydroxy‐terminated liquid fluorinated polymer (HTLF‐1500) as polyurethane phase (namely, GAP‐HTLF‐X full‐IPNs) were successfully fabricated via in situ polymerization without any catalysts at 80°C by azide–alkynyl click chemistry and hydroxyl‐isocyanate urethane reaction. These IPNs were characterized using attenuated total reflectance/Fourier‐transform infrared spectroscopy (ATR/FTIR), uniaxial tensile testing, swelling measurement, and scanning electron microscopy (SEM). The tensile strength of GAP‐HTLF full‐IPNs gradually increased by increasing the weight ratio of Ace‐GAP, but the breaking elongation dramatically decreased compared with elongation at break of HTLF polyurethane. In addition, a small Mn of GAP is beneficial in enhancing the tensile strength, elongation at break and toughness of the IPNs. However, a small Mn of GAP corresponds to increased difficulty of preparing GAP‐HTLF full‐IPNs. GAP1k‐HTLF full‐IPN was not successfully prepared. When the Mn of GAP was 2000 g/mol, the GAP2k‐HTLF‐80 full‐IPN exhibited prominent mechanical performance with a tensile strength of 83.1 MPa, elongation at break of 28.5% and fracture energy of 99.1 kJ/m3. Swelling measurement showed that when the weight ratio of GAP with larger Mn (5, 3, and 2 k) increased to more than 70%, the molecular interpenetration existed in the IPNs, demonstrating the presence of additional physical crosslinks and entanglement for full‐IPNs. SEM studies revealed that highly formed interpenetration and few microphase separations can be observed on the fracture surface of the IPNs with optimal mechanical properties. Combined with the results of mechanical properties, swelling measurement, and SEM studies, the degree of molecular interpenetration and microphase separation were beneficial to improve the mechanical properties of elastomers. This work can provide a certain guiding significance for the preparation of IPN with excellent properties.

Green waterborne synthesis of hemocompatible polycarbonate–polyether polyurethanes

Polyurethane (PU) is a family of biomedical elastomers with promising applications. In this study, we describe the synthesis of a novel waterborne PU with high solid content and low viscosity. The soft segment of the PU consists of polycarbonate diol (PCDL) and polytetramethylene ether glycol. Dimethylolbutanoic acid is used as a chain extender. To stabilize the emulsion in the synthetic process, nonionic groups (polyoxyethylene styrenated phenyl and polyoxyethylene tridecyl ethers) are used as surfactants. PUs with good hydrophilicity and proper hemocompatibility were successfully synthesized using this approach. The chemical composition of the PU was adjusted by changing the soft-to-hard segment ratio. The effects of this composition ratio on the crystallization properties of PU were characterized using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, attenuated total reflectance infrared spectroscopy, thermogravimetric analysis, alternating magnetic field, and contact angle measurements. Film casts from PUs prepared in this study showed good mechanical properties, including Young’s modulus (0.66–48 MPa), tensile strength (11.7–30.9 MPa), and strain at break (173%–579%). Moreover, introducing PCDL in the soft segment during preparation improved the microphase separation and reduced the water contact angle of the films, which enhanced the hydrophilicity of the PU. Our findings demonstrate the potential of the new waterborne PU formulation to significantly improve the performance and durability of biomaterials and blood-contacting devices. Furthermore, this formulation meets the required hemolytic standards, which supports its suitability for medical applications.

Biased motility-induced phase separation: from chemotaxis to traffic jams

We propose a one-dimensional model of active particles interpolating between quorum sensing models used in the study of motility-induced phase separation (MIPS) and models of congestion of traffic flow on a single-lane highway. Particles have a target velocity with a density-dependent magnitude and a direction that flips with a finite rate that is biased toward moving right. Two key parameters are the bias and the speed relaxation time. MIPS is known to occur in such models at zero bias and zero relaxation time (overdamped dynamics), while a fully biased motion with no velocity reversal models traffic flow on a highway. Using both numerical simulations and continuum equations derived from the microscopic dynamics, we show that a single phase-separated state extends from the usual MIPS to congested traffic flow in the phase diagram defined by the bias and the speed relaxation time. However, in the fully biased case, inertia is essential to observe phase separation, making MIPS and congested traffic flow seemingly different phenomena if not simultaneously considering inertia and tumbling. We characterize the velocity of the dense phase, which is static for usual MIPS and moves backward in traffic congestion. We also find that in presence of bias, the phase diagram becomes richer, with an additional transition between phase separation and a microphase separation that is seen above a threshold bias or relaxation rate.

Research on the performance of three-dimensional-braided-glass fiber reinforced in-situ polymerized TPU

In this study, thermoplastic polyurethane (TPU) is prepared by using 4,4′-methylenediphenyl diisocyanate (4,4′-MDI), poly (1,4-butylene adipate) (PBA), and butane-1,4-diol (BDO). PBA as soft segment for TPU. 4,4′- MDI and BDO as hard segment for TPU. The effects of isocyanate index, hard segment content, and soft segment molecular weight on TPU micro-phase separation, molecular weight, and thermal performance are investigated. 3D-Braided-Glass Fiber (GF) reinforced TPU composites are prepared by in-situ polymerized TPU as the matrix resin. Investigation is conducted into how the mechanical properties and microstructure of the composites are affected by the matrix resin TPU’s structural parameters. As the isocyanate index increases, the mechanical properties of the composites first enhance and then weaken, and the interface bonding between TPU and GF gradually deteriorates. Increasing the molecular weight of soft segments has the same trend of change. With the increase of hard segment content, the mechanical properties of the composites are enhanced. The results demonstrate that the mechanical properties of the TPU/GF composites are at their best when the isocyanate index is 1.01, the hard segment content is 43%, and the PBA molecular weight is 2000, with the stretching strength being 289.6 MPa, the impact strength being 141.8 KJ/mm2, the bending strength being 183.2 MPa, and the flexural modulus being 10.7 GPa.

Mechanically Ultra-Robust Fluorescent Elastomer for Elaborating Auxetic Composite.

Fluorescent elastomers are predominantly fabricated through doping fluorescent components or conjugating chromophores into polymer networks, which often involves detrimental effects on mechanical performance and also makes large-scale production difficult. Inspired by the heteroatom-rich microphase separation structures assisted by intensive hydrogen bonds in natural organisms, an ultra-robust fluorescent polyurethane elastomer is reported, which features a remarkable fracture strength of 87.2MPa with an elongation of 1797%, exceptional toughness of 678.4MJm-3 and intrinsic cyan fluorescence at 445nm. Moreover, the reversible fluorescence variation with temperature could in situ reveal the microphase separation of the elastomer in real time. By taking advantage of mechanical properties, intrinsic fluorescence and hydrogen bonds-promoted interfacial bonding ability, this fluorescent elastomer can be utilized as an auxetic skeleton for the elaboration of an integrated auxetic composite. Compared with the auxetic skeleton alone, the integrated composite shows an improved mechanical performance while maintaining auxetic deformation in a large strain below 185%, and its auxetic process can be visually detected under ultraviolet light by the fluorescence of the auxetic skeleton. The concept of introducing hydrogen-bonded heteroatom-rich microphase separation structures into polymer networks in this work provides a promising approach to developing fluorescent elastomers with exceptional mechanical properties.

Photocleavable Polymer Cubosomes: Synthesis, Self-Assembly, and Photorelease.

Polymer cubosomes (PCs) are a recent class of self-assembled block copolymer (BCP) microparticles with an accessible periodic channel system. Most reported PCs consist of a polystyrene scaffold, which provides mechanical stability for templating but has a limited intrinsic functionality. Here, we report the synthesis of photocleavable BCPs with compositions suitable for PC formation. We analyze the self-assembly mechanism and study the model release of dyes during irradiation, where the transition of the BCPs from amphiphilic to bishydrophilic causes the rapid disassembly of the PCs. A combination of modeling and experiment shows that the evolution of PCs proceeds first via liquid-liquid phase separation into polymer-rich droplets, followed by microphase separation within this droplet confinement, and finally, membrane reorganization into high internal order. This insight may encourage exploration of alternative preparation strategies to better control the size and homogeneity of PCs.

Ultrathin, Mechanically Robust Quasi-Solid Composite Electrolyte for Solid-State Lithium Metal Batteries.

Herein, we present the preparation and properties of an ultrathin, mechanically robust, quasi-solid composite electrolyte (SEO-QSCE) for solid-state lithium metal battery (SLB) from a well-defined polystyrene-b-poly(ethylene oxide) diblock copolymer (SEO), Li6.75La3Zr1.75Ta0.25O12 nanofiller, and fluoroethylene carbonate plasticizer. Compared with the ordered lamellar microphase separation of SEO, the SEO-QSCE displays bicontinuous phases, consisting of a Li+ ion conductive poly(ethylene oxide) domain and a mechanically robust framework of the polystyrene domain. Therefore, the 12 μm-thick SEO-QSCE membrane exhibits an exceptional ionic conductivity of 1.3 × 10-3 S cm-1 at 30 °C, along with a remarkable tensile strength of 5.1 MPa and an elastic modulus of 2.7 GPa. The high mechanical robustness and the self-generated LiF-rich SEI enable the SEO-QSCE to have an extraordinary lithium dendrite prohibition effect. The SLB of Li|SEO-QSCE|LiFePO4 reveals superior cycling performances at 30 °C for over 600 cycles, maintaining an initial discharge capacity of 145 mAh g-1 and a remarkable capacity retention of 81% (117 mAh g-1) after 400 cycles at 0.5 C. The high-voltage SLB of Li|SEO-QSCE|LiNi0.5Co0.3Mn0.2O2 displays good cycling stability for over 150 cycles at 30 °C. Moreover, the exceptional robustness of SEO-QSCE enables the high-voltage solid-state pouch cell of Li|SEO-QSCE|LiNi0.5Co0.3Mn0.2O2 with high flexibility and excellent safety features. The current investigation delivers a promising and innovative approach for preparing quasi-solid electrolytes with features of ultrathin design, mechanical robustness, and exceptional electrochemical performance for high-voltage SLBs.

Microphase Separation 3D Printing of Binary Inorganic Polymer Precursors to Prepare Nanostructured Carbon‐Ceramic Multimaterials

AbstractTraditionally, combining carbon and ceramic materials has been challenging due to their different chemical and physical properties. Despite the development of numerous methodologies for their synthesis, these techniques frequently necessitate intricate, multi‐stage protocols and specialized equipment. This study introduces a novel approach for fabricating nanostructured carbon‐ceramic multimaterials through polymerization‐induced microphase separation 3D printing. By combining inorganic precursors, polycarbosilane, and acrylonitrile (AN) within a photocurable resin, heterogeneous nanostructured materials composed of PAN‐preceramic and sacrificial polymer phases are 3D printed. Upon pyrolysis, PAN‐preceramic domains transformed into a carbon‐ceramic matrix while sacrificial polymer domains thermally decomposed to yield nanoscale voids. The utilization of synchrotron X‐ray spectroscopy and microscopy techniques revealed that the phase compositions and microstructure of the resulting multi‐materials are significantly influenced by the initial composition of the resins. The co‐existence of ceramic and carbon phases within a single 3D printed material brought together a combination of properties from both phases, such as the low thermal conductivity of ceramics and the relatively high electrical conductivity of carbon, along with the exceptional chemical resistance. The insights into the microstructure, atomic configuration, and property relationships of the resulting materials have broad implications for the development of multi‐phase nanostructured hybrid materials.

Non-swelling polyelectrolyte complex hydrogels with tissue-matchable mechanical properties for versatile wet wound closure

The stable adhesion of hydrogel-based bioadhesives with tissue-matchable mechanical properties in biological environments remains a significant challenge. In this work, we propose a polyethyleneimine-polyacrylic acid (PEI-PAA, PEA) double-network polyelectrolyte hydrogel with swelling resistant capacity and tunable mechanical properties via one-step UV-initiated polymerization. Driven by electrostatic interactions and polymer-chain entanglement, this PEA hydrogel displays a distinctive microphase separation behavior, which facilitates a wide tunability in mechanical properties. Specifically, the modulus varies from 0.4 MPa to 106 MPa, and the toughness ranges from 1479 kJ/m3 to 7641 kJ/m3, respectively. Besides, the microphase separation endows PEA hydrogel with notable anti-swelling properties in saline, TBS buffer, and blood, leading to consistent adhesion to diverse moist tissues. We further demonstrate that our PEA hydrogels provide matchable mechanical properties and long-lasting adhesion to rat skin and arteries, which promote skin injury healing and effectively halt artery rupture bleeding in vivo. This work presents a straightforward method to generate non-swelling hydrogels and offers novel insight into the development of bioadhesives to meet diverse mechanical requirements.

Incomplete ionic interactions and hydrogen bonds constructing elastomers with water accelerated Self-Healing and self-healing strengthening capacities

Self-healing polymers with microphase separation structure typically require external stimuli to achieve self-healing, and their performance often degrades. To solve these issues, we introduce tertiary amine and carboxyl groups into polymer. The intermolecular ionic interactions and H-bonds contribute to the formation of microphase separation structures, endowing polyurethane elastomers (PU-n) outstanding mechanical properties with a maximum tensile strength and toughness of 20.61 MPa and 59.02 MJ/m3, respectively. The self-healing of the prepared PU-n can be achieved at room temperature and accelerated significantly by water because hard phases can be dissociated, resulting in enhanced molecular movement. After self-healing with water, the enhanced molecular movement and further ionization of ionic groups lead to stronger H-bonds and ionic interactions, promoting more distinct microphase separation. Thus, the mechanical strength is strengthened and the self-healing efficiency can reach 104.72 %. The enhanced molecular movement and strengthened intermolecular interactions when self-healing with water can also be verified through in-depth analysis of molecular dynamics (MD) simulations of the self-healing process. Furthermore, PU-n display remarkable shape memory and can be recycled through exposure to solvents and hot water. This study provides a novel and general method for preparing materials that can self-heal with water and self-strengthen after self-healing.

Multi-cation alkoxy chains with high ion conductivity and durability in cross-linked poly (aryl piperidinium) anion exchange membranes

AEMs with high ionic conductivity and excellent alkali stability are one of the cores to ensure that AEMWE achieves high performance. For the current problems of AEMs, multi-cation side chain crosslinkers present a mitigation strategy for the inherent “trade-off” between ion conductivity and mechanical strength and ensure exceptional alkali resistance. Herein, we introduced the first report on cross-linked AEMs with several hydrophilic multi-cation alkoxy chains, featuring ethylene oxide (EO). The differentiation in the hydrophilic/hydrophobic microphase separation structures, characterized by varying positions of the alkoxy chains within the three-stage multi-cation crosslinker, was explored by experiments and simulation, as well as bearing on the comprehensive performance of AEMs. Notably, EO located in the middle of multi-cations crosslinker was found to establish a coherent and ordered ion channel. QPTP-NOBN15 AEM exhibited the highest OH− conductivity (166.6 mS cm−1) and demonstrated lower water uptake (44.4 %) and swelling ratio (14.5 %) at 80°C. And meticulously designed cross-linked structures, along with ether-free backbones, bestowed upon QPTP-NOBN15 impressive alkali stability. After being retained in 1 M KOH solutions for 1200 h, ion conductivity of QPTP-NOBN15 remained largely unaffected. Furthermore, QPTP-NOBN15-MEA was evaluated by water electrolysis in 1 M KOH solutions at 60°C and found that the current density reached 1.8 A cm−2 at 2.99 V.

Thermoplastic elastomer obtained by photopolymerization‐induced concomitant macrophase and microphase separations

AbstractWe report on concomitant photoinitiated polymerization‐induced macrophase and microphase separation strategies to produce hierarchically structured recyclable poly(n‐butyl acrylate) based elastomeric materials. The investigated crosslinker‐free formulations are composed of n‐butyl acrylate monomer and a UV photo‐initiator mixed with poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐poly(methyl methacrylate) ABA triblock copolymers. Two different pre‐synthesized copolymers are used to control the macrophase separation. One synthesized by nitroxide‐mediated radical polymerization (NMRP), and a second by anionic polymerization (AP). Essentially, NMRP route leads to copolymer with unsaturated chain ends, activated during UV photopolymerization. On the other hand, the copolymer synthesized by AP are chemically inert. That dissimilarity is also highlighted by time‐resolved FTIR and SAXS, performed to monitor respectively monomer conversion and nanostructure evolution during photopolymerization. The experimental data demonstrate that the reactivity of the triblock copolymer impacts drastically the polymerization kinetics and the self‐assembly processes. Finally, the rheological analysis shows that the produced materials present a solid‐like behavior at low frequencies despite a large PnBA content (i.e., 85 wt%). This property is associated to the phase segregation and to the sample hierarchical morphology.