Grafted Side Chains Research Articles

Effect of Grafting Density on the Crystallization Behavior of Molecular Bottlebrushes.

A unique case of sterically constrained crystallization arises in bottlebrush polymers bearing semicrystalline side chains. Bottlebrushes with grafted side chains can form crystalline structures governed by the complex interplay between side chain packing and backbone confinement. The confinement effect can be readily tuned by varying the side chain grafting density, thus affording control over the crystallization behavior of these systems. In this work, the grafting density effect on the crystallization behavior of molecular bottlebrushes comprising poly(ethylene oxide) (PEO) side chains grafted to a methacrylate backbone was systematically studied. Thermal analysis using differential scanning calorimetry showed that the bottlebrush polymers displayed suppressed crystallization temperatures, lower melting temperatures, and reduced crystallinities compared to linear homopolymer PEO. The crystalline morphology was investigated using polarized light, atomic force, and scanning electron microscopy. Isothermal crystallization experiments revealed a nonmonotonous dependence of the nucleation density on the side chain grafting density. The grafting density effect was also investigated using self-seeding experiments, revealing an increased clearing temperature and memory retention at higher grafting densities. This work highlights how grafting density influences the crystallization behavior of semicrystalline bottlebrushes, providing information for the processing and application of these unique polymers.

An endothelium membrane mimetic antithrombotic coating enables safer and longer extracorporeal membrane oxygenation application

Thrombosis and plasma leakage are two of the most frequent dysfunctions of polypropylene (PP) hollow fiber membrane (PPM) used in extracorporeal membrane oxygenation (ECMO) therapy. In this study, a superhydrophilic endothelial membrane mimetic coating (SEMMC) was constructed on polydopamine-polyethyleneimine pre-coated surfaces of the PPM oxygenator and its ECMO circuit to explore safer and more sustainable ECMO strategy. The SEMMC is fabricated by multi-point anchoring of a phosphorylcholine and carboxyl side chained copolymer (PMPCC) and grafting of heparin (Hep) to form PMPCC-Hep interface, which endows the membrane superior hemocompatibility and anticoagulation performances. Furthermore, the modified PPM reduces protein adsorption amount to less than 30 ng/cm2. More significantly, the PMPCC-Hep coated ECMO system extends the anti-leakage and non-clotting oxygenation period to more than 15 h in anticoagulant-free animal extracorporeal circulation, much better than the bare and conventional Hep coated ECMO systems with severe clots and plasma leakage in 4 h and 8 h, respectively. This SEMMC strategy of grafting bioactive heparin onto bioinert zwitterionic copolymer interface has great potential in developing safer and longer anticoagulant-free ECMO systems. Statement of significanceA superhydrophilic endothelial membrane mimetic coating was constructed on surfaces of polypropylene hollow fiber membrane (PPM) oxygenator and its ECMO circuit by multi-point anchoring of a phosphorylcholine and carboxyl side chain copolymer (PMPCC) and grafting of heparin (Hep). The strong antifouling nature of the PMPCC-Hep coating resists the adsorption of plasma bio-molecules, resulting in enhanced hemocompatibility and anti-leakage ability. The grafted heparin on the zwitterionic PMPCC interface exhibits superior anticoagulation property. More significantly, the PMPCC-Hep coating achieves an extracorporeal circulation in a pig model for at least 15 h without any systemic anticoagulant. This endothelial membrane mimetic anticoagulation strategy shows great potential for the development of safer and longer anticoagulant-free ECMO systems.

A Novel Side‐Chain Type Double‐Cation Grafted Poly (Binaphthyl Triphenyl Piperidine) Membranes for Anion Exchange Membrane Fuel Cells

AbstractRecent advancements in anion exchange membrane fuel cells (AEMFCs) have been primarily driven by improvements in anion exchange membranes (AEMs). Aryl ether bond‐free membranes have emerged as a promising avenue for enhancing the overall performance of AEMs. In this study, poly (binaphthyl triphenyl piperidine) with different side‐chain degree (PBTP‐s‐x), possesses double cationic groups, aiming at further enhancing overall performance for AEMs. The use of a twisted stereospecific backbone structure of polymerized binaphthyl and triple biphenyl monomer and grafted side chains of piperidine cationic groups not only improves the microphase separation structure of the membrane, but also improves the alkali resistance. Notably, the PBTP‐s‐100 AEMs exhibit exceptional OH− conductivity, reaching up to 138.21 mS cm−1, and show outstanding mechanical properties with a tensile strength of up to 28 MPa. Additionally, PBTP‐s‐100 displays excellent durability, proved by the NMR spectral consistency and over 80 % ion conductivity retention in 1 M NaOH at 60 °C for 4 weeks. And PBTP‐s‐100 exhibits a higher Lowest Unoccupied Molecular Orbital (LUMO) and a larger energy gap for LUMO and Highest Occupied Molecular Orbital (HOMO) by density functional theory calculation, which indicates it possesses sterling alkaline stability. These findings highlight the potential of PBTP‐s‐100 as a highly performing polymer structure suitable for anion exchange membranes, which is capable of significantly enhancing the performance of fuel cells.

Preparation of a Lignin-Based Cationic Flocculant and Its Application in Kaolin Suspension Treatment.

The preparation of an environmentally friendly and efficient flocculant for solid-liquid separation in industrial wastewater is highly important. In this study, a novel cationic flocculant (AL-g-PAMA) was synthesized by a thermal initiation method using alkali lignin (AL) as the main chain and acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) as the grafted side chains. The structure, thermal stability, and surface morphology of the copolymers were investigated by various characterization methods. The results indicated the successful synthesis of AL-g-PAMA. AL-g-PAMA was applied to improve solid-liquid separation in kaolin suspensions. The results showed that AL-g-PAMA had excellent flocculation-sedimentation and dewatering efficiency. When the dosage of AL-g-PAMA #5 was 600.0 g/t(s), the thickness of the compressed layer was 2.2 cm, the floc settling velocity was 24.1 cm/min, and the transmittance of the supernatant was 84.0%. The moisture content of the filter cake decreased from 55.0% to 43.4% after treatment with AL-g-PAMA #5. The results of zeta potential and focused beam reflectance measurement (FBRM) analysis indicated that bridging and electroneutralization were the main flocculation mechanisms. Therefore, this study extends the potential for using lignin as a bioflocculant and provides a feasible approach to efficiently purify high-turbidity wastewater.

Molecular brushes with long polyfluorene backbones and polymethacrylic acid side chains: Luminescent properties and self‐organization in solutions

AbstractA series of molecular brushes with a polyfluorene (PF) backbone and polymethacrylic acid side chains of varying lengths were prepared by atom transfer radical polymerization. The structure and composition of the synthesized compounds were confirmed by 1H NMR and IR spectroscopy. Effect of the length of the backbone on spectral and conformational parameters of the macromolecules in solutions was analyzed. The grafting density of side chains was about 90%. Spectral methods have been used to determine the dependence of side chain grafting on the luminescent properties of polymer solutions, including quantum yields. It was shown that an optimal length of polymethacrylic acid side chains provides solubility of the polymer brushes. Solutions of PF‐graft‐polymethacrylic acid complexes with the model substance curcumin were investigated. It was established that the molecular brushes containing curcumin form monomolecular micelles. Molecular brushes with zinc phthalocyanine, potential systems for photodynamic, and photothermal therapy, were studied.

Nanostructures of etherified arabinoxylans and the effect of arabinose content on material properties

To further our understanding of a thermoplastic arabinoxylan (AX) material obtained through an oxidation-reduction-etherification pathway, the role of the initial arabinose:xylose ratio on the material properties was investigated. Compression molded films with one molar substitution of butyl glycidyl ether (BGE) showed markedly different tensile behaviors. Films made from low arabinose AX were less ductile, while those made from high arabinose AX exhibited elastomer-like behaviors. X-ray scattering confirmed the presence of nanostructure formation resulting in nano-domains rich in either AX or BGE, from side chain grafting. The scattering data showed variations in the presence of ordered structures, nano-domain sizes and their temperature response between AX with different arabinose contents. In dynamic mechanical testing, three transitions were observed at approximately −90 °C, −50 °C and 80 °C, with a correlation between samples with more structured nano-domains and those with higher onset transition temperatures and lower storage modulus decrease. The mechanical properties of the final thermoplastic AX material can therefore be tuned by controlling the composition of the starting material.

Brownian dynamics simulations of bottlebrush polymers in dilute solution under simple shear and uniaxial extensional flows.

We study the dynamics of bottlebrush polymer molecules in dilute solutions subjected to shear and uniaxial extensional flows using Brownian dynamics simulations with hydrodynamic interaction (HI). Bottlebrush polymers are modeled using a coarse-grained representation, consisting of a set of beads interacting pairwise via a purely repulsive potential and connected by finitely extensible nonlinear springs. We present the results for molecular stretching, stress, and solution viscosity during the startup of flow as well as under steady state as a function of side chain length while keeping the backbone length fixed. In extensional flow, the backbone fractional extension and the first normal stress difference decrease with an increase in side chain length at a fixed Weissenberg number (Wi). Using simulation results both in the presence of and in the absence of HI, we show that this is primarily a consequence of steric interaction resulting from the dense grafting of side chains. In shear flow, we observe a shear-thinning behavior in all cases, although it becomes less pronounced with increasing side chain length. Furthermore, nonmonotonicity in the backbone fractional extension is observed under shear, particularly at high Wi. We contextualize our simulation results for bottlebrush polymers with respect to existing studies in the literature for linear polymers and show that the unique dynamical features characterizing bottlebrush polymers arise on account of their additional molecular thickness due to the presence of densely grafted side chains.

Research progress on the conformational properties of comb-like polymers in dilute solutions.

As a special type of branched polymers, comb-like polymers simultaneously possess the structural characteristics of a linear backbone profile and crowded sidechain branches/grafts, and such structural uniqueness leads to reduced interchain entanglement, enhanced molecular orientation, and unique stimulus-response behavior, which greatly expands the potential applications in the fields of super-soft elastomers, molecular sensors, lubricants, photonic crystals, etc. In principle, all these molecular features can be traced back to three structural parameters, i.e., the degree of polymerization of the backbone (Nb), the degree of polymerization of the graft sidechain (Ng), and the grafting density (σ). Consequently, it is of great importance to understand the correlation mechanism between the structural characteristics and physicochemical properties, among which, the conformational properties in dilute solution have received the most attention due to its central position in polymer science. In the past decades, the development of synthetic chemistry and characterization techniques has greatly stimulated the progress of this field, and a number of experiments have been executed to verify the conformational properties; however, due to the complexity of the structural parameters and the diversity of the chemical design, the achieved experimental progress displays significant controversies compared with the theoretical predictions. This review aims to provide a full picture of recent research progress on this topic, specifically, (1) first, a few classical theoretical models regarding the chain conformation are introduced, and the quasi-two-parameter (QTP) theory for the conformation analysis is highlighted; (2) second, the research progress of the static conformation of comb-like polymers in dilute solution is discussed; (3) third, the research progress of the dynamic conformation in dilute solution is further discussed. The key issues, existing controversies and future research directions are also highlighted. We hope that this review can provide insightful information for the understanding of the conformational properties of comb-like polymers, open a new door for the regulation of conformational behavior in related applications, and promote related theoretical and experimental research in the community.

Wholly sustainable graft copolymers derived from cellulose, lignin, and hemicellulose for high-performance elastomers, adhesives, and UV-blocking materials

Sustainable elastomers derived from renewable biobased resources with excellent mechanical properties and varied functions are highly pursued to substitute traditional petroleum-based polymers yet challenging due to their limited macroscopic performance. In this work, we designed a series of wholly biobased cellulose-graft-poly(vanillin acrylate-co-tetrahydrofurfuryl acrylate) (Cell-g-P(VA-co-THFA) copolymer elastomers with cellulose as the rigid backbone, sustainable VA derived from lignin and soft THFA derived from hemicellulose as the hard and soft segments in the rubbery side chains. Moreover, the grafted side chains can be cross-linked to introduce an additional dynamic network structure via Schiff-base chemistry between the aldehyde and amino groups. The mechanical properties of Cell-g-P(VA-co-THFA) copolymer elastomers, including tensile strength, extensibility, elasticity, and toughness can be facilely manipulated by the VA/THFA feed ratio, cellulose content, and cross-linking density. These Cell-g-P(VA-co-THFA) copolymer elastomers are thermally stable and possess outstanding adhesion behavior and prominent UV-shielding performance. Besides dramatically enhanced mechanical properties, the cross-linked Cell-g-P(VA-co-THFA) counterparts exhibit remarkable shape memory behavior. This work provides a robust and convenient strategy for developing strong and versatile sustainable elastomers with different application demands by integrating different biomass feedstocks via elaborate molecular design.

How does the precursor backbone length affect the grafting efficiency and kinetics for bottlebrush polystyrenes prepared by graft-onto Strategy?

The clarification of the potential dependence of grafting efficiency on the backbone length during the graft-onto reaction process is extremely important for subsequent structure–property study. In this work, by using alkyne-functional polypropargyne acrylate (PPANb, Mw/Mn < 1.10 and Nb = 960, 193, 35) and azide-functional polystyrene (PSNs, Mw/Mn < 1.15 and Ns = 54, 38, 22) as the backbone and sidechain precursors, we have investigated the Nb-dependence of the grafting reaction during the graft-onto click process. Specifically, the influence of solution concentration and feed ratio are investigated, and a combination of SEC characterization, Gaussian fitting and theoretical analysis is used to estimate the Nb-dependent grafting reaction for the bottlebrush product (PPANb-g-PSNs). The main findings include: 1) when the reaction time (t) is sufficient long (t = 24 h), the grafting efficiency is found to be nearly irrelevant with Nb, even if we consider 2 ∼ 5 times of difference in the diffusion coefficient (D) based the well-known scaling relation of D ∼ Nb1/2 in the semidilute reaction solution; 2) the time-dependent kinetics investigation further shows abnormal and different pathways for different backbone lengths when 0 min < t < 10 min, but the final grafting efficiency determined at t = 300 min shows no much difference, going back to the preliminary result of equilibrium state at t = 24 h; 3) the origin of abnormal pathways may be attributed to the relatively poor signal-to-noise ratio and potential dependence of dn/dC of PPANb-g-PSNs product on the composition at low grafting density range, which needs clarification in future. For the first time, our result has unambiguously demonstrated that, for a mixed solution of reaction system composed of backbone precursors with their lengths differing by hundreds of times, the polydispersity effect of the backbone length does not affect the final grafting efficiency during the process, no matter for long or short sidechain grafts. The result implies that it is the local dynamics of chain segments, instead of the overall translational diffusion dominates the graft-onto process in the concentration-regime studied.

Effect of carboxyl group introduction and graft modification on the thermal properties and Fe wall adsorption performance of HNBR

Hydrogenated nitrile butadiene rubber (HNBR) has been widely used in petrochemical, aerospace, and other fields for its excellent properties. In this study, molecular dynamics methods were employed to construct molecular models of HNBR and hydrogenated carboxyl butadiene rubber (HXNBR). It was found that the introduction of carboxyl groups significantly enhanced the mechanical properties of the material, whereas the glass transition temperature of the material increased by 9.96% and the thermal conductivity decreased by 17.3%. Subsequently, the grafted hydrogenated carboxylated nitrile butadiene rubber (HXNBR-Rx) model and the HXNBR-Rx/Fe bilayer adsorption model, which incorporate grafting modifications with of C5H11OH, C10H21OH, C15H31OH, C20H41OH and C25H51OH, were constructed. In comparison between their thermal properties and the adsorption properties on the metal walls, we revealed that as the number of grafted side chain carbon atoms increased, both the mechanical properties and the glass transition temperature of the material showed a trend of first decreasing and then increasing, while the thermal conductivity of the material first increased and then decreased. Furthermore, the effect of grafting on the material properties was analyzed at the molecular level in terms of free volume fraction, interfacial interaction energy, and relative atomic concentration. The simulation results can provide some theoretical guidance for optimizing the thermal properties of HNBR materials and the adsorption capacity of the metal walls while maintaining their oil resistance and mechanical properties.

Grafting α-aminoketone to SMA via highly efficient amide bond and their performances as macrophotoinitiators

Water-soluble macrophotoinitiators that can realize a high photoactivity together with low migration in waterborne photopolymerization systems are very necessary. However, the precise, highly efficient preparation of macrophotoinitiators remains a substantial challenge, such as grafting side chains according to stoichiometric ratios. Herein, based on styrene maleic anhydride copolymer (SMA) prepared by photopolymerization, water soluble macrophotoinitiators SMA5k-Ns and SMA13k-Ns series with controllable structure were successfully prepared through the amino bond of α-aminoketone small-molecule photoinitiator with maleic anhydride moieties. All of them exhibited excellent water dispersion properties, and solution photopolymerizations investigation showed they can be used as photoinitiators for radical polymerization with high conversion (up to 95%) in waterborne systems under LED@365–405 nm. Furthermore, the migration stabilities of these photoinitiators in photocured hydrogels were better than those of commercial photoinitiators. High efficiency and low migration make them have great potential applications in food packaging and biological materials.

Phenylene‐containing polyethylenimine‐like polymers absorb and release CO2 to blow biomass‐based polyurethanes

AbstractCO2 adducts of hydrophobically modified polyethylenimines (PEIs) are promising alternatives to global warming halogen‐containing blowing agents of polyurethanes (PUs), despite the high cost of the raw material PEIs. Herein, an economical synthesis of PEI‐like polymers was explored via condensation between pentaethylenehexamine and terephthalaldehyde, followed by chemical reduction of the as‐formed Schiff base linkages. The resultant p‐phenylene‐containing polyamine polymers (PEIPs) could be grafted with alkyl (Cn) side chains and adducted with CO2 to form a new type of CO2‐releasing blowing agents for PUs designated as yCn‐xPEIP‐CO2s, where x and y represent the backbone molecular weight and the side chain grafting rate, respectively. Among them, the specimen 10%C8−3.6 kPEIP‐CO2 was the most effective in terms of good dispersibility in PU raw materials, low foam density (about 51 kg/m3), and uniform pore morphology. Moreover, the phenylene linkages enhanced the hydrophobicity of the consequent CO2 adducts and weakened the intermolecular hydrogen bonding and ionic attraction, both facilitating the dispersion of the corresponding blowing agents into a castor oil‐derived polyol, Polycin M‐365. The specimen 10%C8−3.6 kPEIP‐CO2 could disperse as suspended fine floccules that finally aggregated into a flocculent, liquid‐like bottom layer, being easily redispersed into the bulk. The unique compatibility with plant oil‐derived polyols and the economic availability would make the PEIP‐based blowing agents suitable for the next generation of sustainable and biomass‐based PU foams.

Study on the preparation method of porous membranes with single pore size distribution and tailored pore sizes by the induced swelling effect of pre-set graft side chains

To improve the sieving accuracy of material separation, it is necessary to develop a porous membrane with tailored pore size and narrow pore size distribution. Polyvinylidene fluoride (PVDF), the mainstream membrane material, is a semi-crystalline polymer. On the basis of the high elastic state of the PVDF molecular chain in the amorphous region at room temperature, a novel method was proposed to prepare porous membranes with single pore size distribution and tailored pore sizes in this paper. First, 1,3-bis (tris(hydroxymethyl)methylamino) propane (Bis-Tris propane) was grafted onto the PVDF-CTFE main chain during casting solution preparation, and the membranes with the thin and nonporous skin layers were prepared by non-solvent-induced phase separation (NIPS), which had almost no water flux. The membrane with the nonporous skin layer produced a water flux of 35.3 L ∙ m−2∙ h−1∙ bar−1 after soaking in the alkaline glycine solution. FTIR and EDX tests demonstrated that small molecular glycine can be guided into the membrane matrix by the affinity with the polar groups on the pre-set side chains, inducing the reactive swelling effect, which led to the formation of new through holes. Subsequently, the membrane with the nonporous skin layer was initially soaked in ethanol to form pores in advance, then the induced reactive swelling of pre-set graft side chains was carried out. The water flux of obtained membrane was significantly up to 96.9 L ∙ m−2∙ h−1∙ bar−1, proving that the pre-pore forming process successfully strengthened the reactive swelling-caused pore generation effect. Furthermore, based on the enhanced swelling-caused pore generation strategy, amino acids with different molecular sizes were induced to the reactive swelling effect in the amorphous regions. The mathematical fitting showed a linear correlation between the average pore size of the membrane and the molar hydration volume of amino acids, and the membrane was single pore size distribution, verifying that controllably tailored membrane pore size can be realized by the reactive swelling effect of the reactive small molecule with different molecular sizes. Compared to some membranes with single pore size distribution prepared by track etching and anodic oxidation method, the membranes prepared by this method had higher water flux. The water contact angle result clarified that the membrane surfaces and pore channels had excellent hydrophilicity. The reactive swelling did not change the crystallinity and porosity, so the mechanical strength of the membrane did not deteriorate.

Facilely Control Grafting Density and Side Chain Composition of Bottlebrush Polymer.

Control over polymer architecture and composition is essential for disclosing structure-property relationships and developing high-performance materials. Herein, a new method is successfully developed to synthesize bottlebrush polymer (BP) with controllable graft density and side chain composition by "grafting-from" strategy using in situ halogen exchange and reversible chain transfer catalyzed polymerization (RTCP). The main chain of the BP is first synthesized by the polymerization of methacrylates containing alkyl bromide as a side group. Then, the alkyl bromine is quantitatively converted to alkyl iodide with sodium iodide (NaI) via in situ halogen exchange to efficiently initiate the RTCP of methacrylates. By adjusting the input amount of NaI and monomers in sequence, BP named PBPEMA-g-PMMA/PBzMA/PPEGMEMA which contains three different kinds of polymer side chains including hydrophilic PPEGMEMA, hydrophobic PMMA, and PBzMA is synthesized with narrow molecular weight distribution (Mw /Mn ≤1.36). The grafting density and the chain length of each polymer side chain are well controlled by the addition of NaI in batches and following RTCP. Moreover, the obtained BP self-assembled into spherical vesicles in aqueous with hydrophilic coronal structure, core region, and the hydrophobic wall between the former two, which enables to wrap hydrophobic pyrene and hydrophilic Rhodamine 6G separately or simultaneously.

Combined Core Stability and Degradability of Nanomedicine via Amorphous PDLLA-Dextran Bottlebrush Copolymer for Alzheimer's Disease Combination Treatment.

Nanomedicine faces the challenges of infinite dilution, shear force, biological protein, or electrolyte competition. However, core cross-linking leads to biodegradability deficiency and brings inevitable side effects of nanomedicine on normal tissues. In order to overcome this bottleneck problem, we turn to amorphous poly(d,l)lactic acid (PDLLA)-dextran bottlebrush to emphasize the core stability of nanoparticles, and the amorphous structure offers an additional advantage of fast degradation property over the crystalline PLLA polymer. The graft density and side chain length of amorphous PDLLA together played important influence roles in controlling the architecture of nanoparticles. This effort produces structure-abundant particles, including micelles, vesicles, and large compound vesicles after self-assembly. Here, the amorphous bottlebrush PDLLA was verified to play a beneficial role in the structure stability and degradability of nanomedicines. The codelivery of the hydrophilic antioxidant of citric acid (CA), vitamin C (VC), and gallic acid (GA) via the optimum nanomedicines could effectively repair the SH-SY5Y cell damage caused by H2O2. The CA/VC/GA combination treatment repaired the neuronal function efficiently, and the cognitive abilities of senescence-accelerated mouse prone 8 (SAMP8) recovered.

Prediction of mechanical properties for a grafted polypropylene system via transfer learning with a small database

The increasing demand for polymer dielectrics in different scenarios, such as electrical insulation cable, requires elevated electrical and mechanical properties. In order to understand the relationship between mechanical properties and the structure of grafted monomers in a grafted polypropylene (PP) system, a design framework based on the transfer-learning method has been proposed for designing grafted side chain structure in PP system. 22 samples of polypropylene-grafted polymer are synthesized. Through a well-trained multi-layer perceptron model for predicting glass transition temperature (Tg), mechanical properties of the grafted PP have been well predicted by the transfer-learning method. Meanwhile, the grafting group structures are divided into nine substructures. By assembling these substructures, the chemical space is established for prediction. Moreover, candidates with satisfied deep traps and flexible mechanical properties are screened out for reference. This work turns qualitative understanding into a quantitative analysis based on mathematical models and broadens the application of polymer materials design with a small dataset.

Development of a ZIF-91-Porous-Liquid-Based Composite Hydrogel Dressing System for Diabetic Wound Healing.

Porous metal-organic framework (MOF) liquids with permanent porosity, good fluidity, and fine dispersion attract broad attention in catalysis, transportation, gas storage, and chemical separations. Yet, the design and synthesis of porous MOF liquids for drug delivery remain less explored. Herein, a simple and general strategy is reported to prepare ZIF-91 porous liquid (ZIF-91-PL) via surface modification and ion exchange. The cationic nature of ZIF-91-PL not only renders it antibacterial but also with high curcumin loading capacity and sustained release. More importantly, the acrylate group on the grafted side chain of ZIF-91-PL makes it feasible to crosslink with modified gelatin through light curing, and the obtained hydrogel shows a significantly improved healing effect on the wound of diabetes. This work demonstrates for the first time, a MOF-based porous liquid for drug delivery, and the further fabrication of composite hydrogel may have potential applications in biomedical science.

Tailoring high mechanical performances of self‐healable poly(vinyl alcohol)‐based elastomers via judicious grafting of side chains

AbstractSelf‐healing conductive materials have become promising candidates for flexible sensor devices. However, the mechanical properties of the substrate elastomers are often poor due to the inherent performance of the materials. Here, a poly(vinyl alcohol) (PVA)‐based self‐healing material with high strength and good thermal stability was prepared by side‐linked grafting modification of PVA with a one‐step esterification reaction. Benefiting from the hydrogen bonds and ion coordination between iron ions and carboxyl groups, the synthesized elastomer exhibited excellent mechanical properties (tensile strength of 38.6 MPa, fracture elongation of 1565.0%) and good self‐healing performance (self‐healing efficiency of 53.4% at room temperature). In addition, the high sensitivity and self‐healing performance of a silver nanowire‐coated elastomer strain sensor demonstrated the wide potential applicability of the prepared PVA‐based elastomers in health care, electrocardiography and safety monitoring. © 2023 Society of Industrial Chemistry.

Poly (aryl piperidinium) anion exchange membranes for acid recovery: The effect of backbone structure

The anion exchange membrane (AEM)-based diffusion dialysis is considered as an efficient strategy for the recovery of acid. Recently, the novel ether-free poly (aryl piperidinium) (PAP) AEMs modified by side chain grafting has been applied in the area of acid separation, showing excellent acid flux. However, there is little study focusing on the influence of polymer backbone structures of AEMs in acid separation. Herein, a series of PAP AEMs with different backbone arrangements based on diphenyl, m-terphenyl, and p-terphenyl were prepared for acid separation via diffusion dialysis. Compared with diphenyl and p-terphenyl, the m-terphenyl-based AEM exhibits a fantastic comprehensive performance, with a dialysis coefficient of 20.1 × 10-3 m h−1 and H+/Fe2+ selectivity of 196. The acid flux and selectivity can be kept after 7 days of acidic stability test in 1 mol/L HCl and 0.25 mol/L FeCl2. This can be attributed to its unique spatial configuration that induces a microphase-separated structure, which is beneficial to H+ conduction. Meanwhile, its high rigidity and low solubility could restrain the water uptake and swelling, and thus reduce the Fe2+ flux and enhance the selectivity. Furthermore, the stability of all PAP AEMs was tested in 2 mol/L HCl at 60 °C for 60 days, and their ionic conductivities still remained above 90 %. This study highlights a simple and reliable strategy to enhance the acid separation performance of AEMs via the facile backbone design.