Copolymerization Reaction Research Articles

Eco‐friendly synthesis of non‐isocyanate polyurea using PET and CO2 upcycling: A double green approach

AbstractFrom the perspective of sustainability, this research explored both the recycling of polyethylene terephthalate (PET) and the conversion of carbon dioxide (CO2) into polymer materials. To this end, a series of copolyurea specimens were synthesized through the polycondensation of carbon dioxide with hexamethylenediamine (HDA) and terephthalic dihydrazide (TDH), where TDH was derived from the chemical recycling of PET via the aminolysis method. FTIR spectroscopy, 1H NMR, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) characterized the products of PET recycling and synthesized copolyureas. Additionally, we sought to identify the optimal parameters for both the recycling and copolymerization processes. The results of identification analyses for both the recycling and copolymerization reactions confirmed the formation of the desired structures. An increase in the hard segment (TDH) led to discrepancies between the intended and actual monomer ratios in the synthesis, possibly due to dimethyl sulfoxide (DMSO) solubility issues or unreacted TDH. Furthermore, the TGA analysis indicated that the initial degradation temperature (Td,5%) of the copolymer increased with the proportion of aromatic rings in the hard segment, underscoring the complex interactions within the copolymer matrix affecting its thermal and structural properties. The DSC results revealed that for copolyureas with the formula HDAxTDH100–x (where x = 50, 60, 70, 80, 90), reducing the x fraction or increasing the TDH content lowered the melting temperature. Furthermore, at a high percentage of TDH, the melting point disappeared entirely due to the destruction of the crystalline structure, indicating a critical threshold where the copolymer transitions from a semi‐crystalline to an amorphous state.

Evaluation of Grafting Parameters of Styrene onto Alkaline Modified Sugarcane Bagasse using Fe2+/H2O2 and Fe2+/H2O2-N2H4 initiator systems and Characterization of the Hydrolyzed Grafted Polystyrene Chains

Cellulose the most abundant natural fibre can be modified, via grafting with vinyl monomers, in homogenous or heterogeneous reaction medium. Therefore, the objective of this paper was to study the grafting parameters of styrene onto alkaline modified sugarcane bagasse using Fe2+/H2O2 and Fe2+/H2O2- N2H4 initiator systems and characterized the hydrolyzed grafted polystyrene chains for their viscometry and average molecular weight distributions using standard appropriate methods. The grafting parameters increases within 0.10-0.25 M styrene concentration in both initiator systems and initiator concentration within the range 1.0x10-3 to 6.0x10-3 for Fe2+/H2O2- N2H4 and 1.0x10-3 to 9.0x10-3 for Fe2+/H2O2 systems, albeit with higher values in the former system. These parameters decrease at higher monomer and initiator concentrations in both systems. The viscometry of hydrolyzed polystyrene chain prepared at optimum initiator concentrations and 0.10-0.30 M styrene concentration in both initiator systems are in the range (1.6416-4.5327 cP), (0.6416-3.5327 cP) and (73.2277-202.1927 cP) for relative, specific and inherent viscosities respectively, consistent with increases in activation energy of flow (1.24-5.30 KJmol-1) and average viscosity molecular weights (307.92-565.79 gmol-1) , these parameters decreases at higher monomer concentration in both initiator systems. The number and weight-average molecular weight distributions and polydispersity indices indicates that grafted polystyrene chains in Fe2+/H2O2 system are broader and more polydispersed than those for Fe2+/H2O2- N2H4 initiator system. The results showed that the hydrazine enhanced initiator system was more effective for the copolymerization reaction with polystyrene polydispersity indices comparable to those of synthetic chain-growth polymers.

Binder‐induced inorganic‐rich solid electrolyte interphase and physicochemical dual cross‐linked network for high‐performance SiOx anode

AbstractSilicon oxide (SiOx) is heralded as the forefront anode material for high‐energy density lithium‐ion batteries, owing to its exceptional specific capacity. Nevertheless, the traditional combination of polyacrylic acid binder and acetylene black conductive carbon continues to struggle with the immense stress induced by the repetitive volume expansion and contraction processes. Here we report a high ionic conductivity, sulfonyl fluoro‐containing binder for SiOx anode via free radical copolymerization reaction between perfluoro (4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride and acrylic acid. The electrode fabrication process incorporated amino‐functionalized carbon nanotubes (CNT‐NH2) as the conductive agent. A three‐dimensional conductive network structure is constructed through physical and chemical double cross‐linking interactions between the ‐COOH and ‐SO2F functional groups of PAF0.1 binder, the ‐NH2 groups of CNT‐NH2, and the ‐OH groups on the surface of SiOx, including hydrogen bonds and covalent bonds. In addition, the binder induces the formation of a solid electrolyte interphase (SEI) rich in inorganic components such as Li2O, Li2SO3, Li2CO3, and LiF. Benefiting from the synergistic effects of the physically and chemically double cross‐linked three‐dimensional conductive network constructed by the PAF0.1 binder and CNT‐NH2, coupled with the rich‐inorganic SEI, the SiOx anode delivers exceptional rate performance, cycle stability, and lithium‐ion diffusion dynamics.

Synthesis and luminescence properties of carbon quantum dots with core@shell structures

The luminescence stability of carbon quantum dots (CQDs) in air impedes their extensive applications. Ample –NH2 groups on the surface of a green carbon quantum dots (GCQDs) had high organic reactivity, the surface of GCQDs was modified with allyl functional groups through a simple surface substitution reaction (named as GCQD-A). The surface of the GCQD-A was continuously formed a thin organic shell by free radical copolymerization reaction with methyl methacrylate and styrene respectively, and they were named as GCQD@PMMA and GCQD@PS respectively. The allyl functional groups on the surface of GCQD-A, the shell composition of GCQD@PMMA and GCQD@PS were characterized by their 1H nuclear magnetic resonance (1H NMR) data and infrared adsorption spectra. The luminescence stabilities for GCQD@PMMA and GCQD@PS in air were greatly improved compared with that for the GCQDs. The work can provide a novel method to get stable luminescence of CQDs in air, and it will extend their application areas in solid state.

Novel ionic polymers encompassing di-cationic pyridinium hydrazones and aromatic ester as potent antimicrobial agents against resistant bacteria

In this work, readily achievable synthetic pathways including quaternization, metathesis and copolymerization reactions were utilized for the construction of a new di-pyridinium monomers and their respected ionic polymers scaffold with ester fragments. All synthesized material were well characterized by spectroscopic experiments. The surface morphology and thermal study of the produced polyesters were carried out using SEM, PXRD, and TGA analysis. The impact of the counter anions on the crystallinity and thermal analysis of the polymer network was confirmed by thermal analysis and surface investigation. The related polyesters' crystallinity was decreased, and their thermal stability was increased by the TFSI anion. Various significant consequences regarding the development of innovative antibacterial agents along with specific therapies. Subsequently, we evaluated the antimicrobial, antibiotic resistant strains, and anti-prophage properties of these novel class of ionic and poly-ionic materials. Throughout antibacterial studies, the M-Br monomer excelled all synthesized materials, although PPy-TFSI and its monomer outperformed antibiotic-resistant organisms. Both M-PF6 and PPy-PF6 decreased S. aureus bacteriophage proliferation. Understanding the bacterial species or strains that are vulnerable to polyesters encourages subsequent studies in this field to focus on creating targeted therapies for illnesses caused by these pathogens.

Accurate Determination of Reactivity Ratios for Copolymerization Reactions with Reversible Propagation Mechanisms

Accurate Determination of Reactivity Ratios for Copolymerization Reactions with Reversible Propagation Mechanisms

PIM-1-assisted structuring of amine-functionalized porous organic copolymer for post-combustion carbon dioxide capture

Capturing CO2 from flue gas of coal-burned power plants has been considered to be a promising technology to mitigate the environmental problems caused by rising level of CO2 at the atmosphere. Amine-functionalized adsorbents, showing impressive CO2 adsorption capability and selectivity even at low CO2 partial pressure, face the challenge of permanent structural changes and performance deterioration due to the irreversibly bonding of SO2, a common impurity of flue gas, particularly under humid condition. Besides, the reported amine-functionalized adsorbents are usually nano-sized powders, impractical for industrial applications. Therefore, the development of efficient, stable, and structured CO2 adsorbents is still an urgent need. Herein, we develop a novel structured mixed-matrix adsorbent (PIM-PP-DETA), using a diethylenediamine-appended porous organic copolymer (PP-DETA, prepared by a copolymerization reaction of dichloro-p-xylene and 4,4′-bis(chloromethyl)biphenyl and a one-step amine grafting process) as main adsorbent and PIM-1 as polymer matrix through a phase inversion process. The as-developed PIM-PP-DETA not only exhibits high CO2 adsorption capacity and outstanding CO2 selectivity over N2, but also shows fast adsorption kinetics and high stability under repeated adsorption-desorption cycling under dynamic flow conditions. Furthermore, PIM-PP-DETA possesses high tolerance towards acidic and moist environments, with CO2 adsorption capacity remained at a relatively high level after SO2 and humid exposure, suggesting its potential usage to post-combustion CO2 capture.

Designing network structure hydrogels derived from carrageenan- phosphated polymers by covalent and supramolecular interactions for potential biomedical applications

Recently, various efforts have been made to explore the potential of natural polysaccharides derived from sea weeds to promote sustainable development. Herein, carrageenan (CG), a polysaccharide extracted from red sea algae, was utilized to design network structures as hydrogels, aimed at significant applications in drug delivery (DD) systems. Hydrogels were designed by graft copolymerization reaction of poly(bis [2-methacryloyloxy] ethyl phosphate [poly(BMEP)] and poly(acrylic acid) [poly(AAc)] onto CG in the presence of a crosslinking agent. Hydrogels were developed by covalent linkage by graft copolymerization and supramolecular interactions, existing in the copolymers. Copolymers were characterized by Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance (NMR), and X-ray diffraction (XRD) instrumentations. The drug diffusion exhibited a sustained pattern due to polymer-drug interactions. The drug release followed non-Fickian diffusion mechanism and the release profile was most accurately depicted by first order kinetic model. The biocompatible nature of the copolymer was demonstrated from the hemolytic index value signifying minimal adverse interactions with blood component upon exposure. A protein adsorption test was performed using bovine serum albumin (BSA), exhibiting 8.15 ± 0.26 % albumin adsorption. Polymers exhibited mucoadhesive character, evidenced by their requirement of a detachment force measuring 195 ± 4.72 mN for separation from the membrane during interactions with the mucosal surface. The hydrogels exhibited antioxidant properties, evidenced by 2, 2′-Diphenylpicrylhydrazyl (DPPH) assay, revealing copolymer capable of scavenging 58.21 ± 2.26 % of free radical. The hydrogel revealed antimicrobial activity against P. aeruginosa and S. aureus bacteria, a property further enhanced in hydrogels with the drug doxycycline. These findings suggest suitability of these hydrogels for biomedical applications, with a significant emphasis on drug delivery.

Composite polymer films with semiconductor nanocrystals for organic electronics and optoelectronics

Organic materials and, in particular, polymer films enhanced with certain nanocrystals have a potential for wide application in electronics and optoelectronics due to their organic flexibility, lightweight, simple integration, affordable manufacturing cost, and low environmental impact of their production. The purpose of this research is to investigate the electrical properties of polymer-based composite films containing Cd1–xCuxS nanocrystals in order to determine their prospects for use as conductive layers in organic electronics and optoelectronics. The paper contains a detailed description of the synthesis method of hybrid nanocomposite films based on peroxide reactive copolymer (PRC) with Cd1–xCuxS nanocrystals. The defect structure of the films is studied by analyzing the photoluminescence spectra. Current-voltage characteristics of the films with different Cd and Cu contents in the Cd1–xCuxS nanocrystals embedded into the polymer matrix, deposited on glass substrates are measured in the dark and under light illumination. The film conductivity is found to increase with the Cu content in the Cd1–xCuxS nanocrystals. The carrier transport corresponds to the Ohm law at low voltages and the space charge limited current (SCLC) or Poole–Frenkel mechanisms at higher ones. The conductivity of the polymer-based hybrid nanocomposite films has a weak dependence on the intensity of light illumination. The explanation of the obtained experimental results is proposed.

INFLUENCE OF EXTERNAL FACTORS ON BINARY SYSTEMS DURING RAFT POLYMERIZATION

The article discusses the method of radical copolymerization as an effective way to obtain new polymer compounds with practically valuable properties. This method is based on the free radical mechanism, in which the sequential addition of molecules of an unsaturated monomeric compound to a growing macroradical occurs. Due to the relative simplicity of this method, it makes it possible to produce a large number of polymers for various purposes on an industrial scale. Unsaturated polyesters of various compositions and molecular weights, which can significantly affect the properties of the final products, are considered promising coreagents capable of entering into radical copolymerization reactions with vinyl monomers. The article discusses the results of studies of polymer gels obtained on the basis of unsaturated carboxylic acids. The author refers to previous studies, showing that such gels have high sorption capacity, while the starting material does not have similar properties. The following describes the structure analysis of p-PGFPh copolymers with these acids, where important characteristics such as the presence of ionized units in vinyl monomers are discussed. The significance of these studies for the creation of materials with the necessary properties of sorption and interaction with other substances. Study of the influence of environmental pH on the behavior of copolymers based on polypropylene glycol fumarate phthalate with acrylic and methacrylic acids. The equilibrium degree of swelling of the studied copolymers in aqueous solutions at different temperatures was also determined by the gravimetric method. In general, analysis of the swelling curve when varying the acidity/alkalinity of the external solution indicates that the gels we synthesized are polyelectrolytes; analysis of the curve when exposed to temperature, the resulting copolymers are thermosensitive. Thus, the main idea of the article is the importance of using unsaturated carboxylic acids to create polymer gels with high sorption capacity and emphasizes the importance of analyzing the structure of such materials to understand their properties and application possibilities.

Design of degradable hybrid dual-crosslinked polymer for high-efficiency profile control in high temperature reservoirs

Profile control and water plugging are key technologies to enhance oil and gas recovery. Traditional plugging materials, due to short gelation time, low mechanical strength, and difficulty in balancing plugging and protection, thus limiting application in high temperature reservoirs. Herein, a degradable hybrid dual-crosslinked polymer was prepared by employing a copolymerization - dual-grafting and physical adsorption design strategy. The dual-crosslinked process and reaction mechanism were analyzed using infrared spectroscopy and differential scanning calorimetry. The mechanical properties, water dilution resistance, aging stability and degradability of the dual cross-linked composite were also investigated. The solvation forces enable silica particles to exhibit excellent suspension stability in a PEG solvent. The temperature ranges from normal atmospheric temperature (20 °C) to reservoir temperature (140 °C), with the apparent viscosity falling within the range of 10–1200 mPa·s, meeting the requirements for mixing and injection. The combination of free radical copolymerization and click reaction is utilized to control the gelation time (2–10 h) in high temperature environment (140 °C), which is favorable for regulating the action position of the plugging agent in the reservoir. The cured material exhibits excellent mechanical strength owing to the presence of dual-crosslinking and inorganic hybridization, with a compressive strength of 0.221 MPa and a peak strain of 55.3 %. Furthermore, this composite material undergoes hydrolysis through an addition-elimination reaction, transitioning from a solid to a liquid state within 24 h, thereby aiding in the restoration of productivity in the temporarily shielded target layer. Compared to traditional materials, this dual-crosslinked composite system have the advantages of controllable gelation time, high mechanical strength, aging resistance, and degradability, making it suitable for profile control in high temperature reservoirs (140 ℃, 21.81×104 mg/L).

Innovative Approach to Chiral Polyurethanes: Asymmetric Copolymerization with Isocyanates.

The introduction of nitrogen-containing functional groups to chiral polymer backbones enables the tailoring of physical properties and offers opportunities for further post-polymerization modification. However, the substrate scope of such polymers is extremely limited because monomers having nitrogen-containing groups can change coordination state with respect to the metal centers, thus decreasing the activity and enantioselectivity and even poisoning the catalyst completely. In this paper, we report our attempts to carry out the asymmetric copolymerization of meso-epoxide with highly reactive isocyanates. In particular, we found that biphenol-linked bimetallic Co(III) complexes with multiple chiral centers are very efficient in catalyzing this asymmetric copolymerization reaction, affording optically active polyurethanes with a completely alternating nature and a high enantioselectivity of up to 94% ee. Crucially, we identified that the steric hindrance at the phenolate ortho position of the ligand strongly influences the catalytic activity and product enantioselectivity. In addition, density functional theory calculations revealed that the highly sterically bulky substituents change the mechanism from bimetallic to monometallic, and result in the unexpected inversion of the chiral induction direction. Moreover, the high stereoregularity of the produced polyurethanes enhances their thermal stability. This study offers a versatile methodology for the synthesis of chiral polymers containing nitrogen functionalities.

Innovative Approach to Chiral Polyurethanes: Asymmetric Copolymerization with Isocyanates

AbstractThe introduction of nitrogen‐containing functional groups to chiral polymer backbones enables the tailoring of physical properties and offers opportunities for further post‐polymerization modification. However, the substrate scope of such polymers is extremely limited because monomers having nitrogen‐containing groups can change coordination state with respect to the metal centers, thus decreasing the activity and enantioselectivity and even poisoning the catalyst completely. In this paper, we report our attempts to carry out the asymmetric copolymerization of meso‐epoxide with highly reactive isocyanates. In particular, we found that biphenol‐linked bimetallic Co(III) complexes with multiple chiral centers are very efficient in catalyzing this asymmetric copolymerization reaction, affording optically active polyurethanes with a completely alternating nature and a high enantioselectivity of up to 94 % ee. Crucially, we identified that the steric hindrance at the phenolate ortho position of the ligand strongly influences the catalytic activity and product enantioselectivity. In addition, density functional theory calculations revealed that the highly sterically bulky substituents change the mechanism from bimetallic to monometallic, and result in the unexpected inversion of the chiral induction direction. Moreover, the high stereoregularity of the produced polyurethanes enhances their thermal stability, and they can be selectively decomposed into oxazolidinones. This study offers a versatile methodology for the synthesis of chiral polymers containing nitrogen functionalities.

Antimicrobial, anti‐inflammatory, and antioxidant evaluations of ammonium and phosphonium salts based on poly(vinylbenzyl chloride‐co‐acrylonitrile)

AbstractPolymers with ammonium or phosphonium salts have been known to possess antimicrobial activity. Herein, synthesis of poly(vinylbenzyl chloride‐co‐acrylonitrile) (P(VBC‐co‐AN)) is reported via a free radical polymerization by employing AIBN as initiator. The copolymer was then quaternized using triethylamine, triphenylphosphine, and tributylphosphine. The triphenylphosphonium salt was selected for further modification, on which the polyacrylonitrile chains were reacted with two different amines: tris (2‐aminoethylamine) and diethylenetriamine. The copolymerization, quaternization, and amination reactions were confirmed by spectroscopic and morphologic analysis besides the thermal features. The water uptake of modified polymers was investigated, where tributylphosphonium salt (KH4) showed the highest water uptake capacity (41 g/g). The antimicrobial assay findings demonstrated that all the evaluated copolymers displayed a wide range of antimicrobial activity against different multidrug resistant human pathogens, for example polymer coded KH4 containing tributylphosphonium salt showed the highest growth inhibition rates against Staphylococcus aureus and Staphylococcus epidermidis populations, recorded 87% and 72%; respectively. The anti‐inflammatory activity revealed that all the quaternized copolymers have a protection effect of human erythrocyte membrane against lysis. Antioxidant results revealed that all quaternized copolymers displayed 1,1‐diphenyl‐2‐picryl hydrazyl scavenging activities. Among the studied copolymers, aminated copolymer coded (KH6) exhibited the highest scavenging activity, with IC50 ~ 120 μg/mL.

Emulsion copolymerization of 2-methylene-1,3-dioxepane (MDO) and acrylate monomers: Incorporation vs hydrolysis

The incorporation of polyester moieties to the backbone of waterborne polymer dispersions by the emulsion copolymerization of 2-methylene-1,3-dioxepane (MDO) and acrylate monomers (n-butyl acrylate and 2-octyl acrylate) is explored in this work. Due to the competition between the consumption of MDO by hydrolysis (MDO is very sensitive to water) and by copolymerization reactions, seeded semibatch emulsion copolymerizations were carried out varying the temperature of the reaction, the feeding rates of the comonomers, and maintaining a basic pH (∼pH = 8) that decreases notably the rate of hydrolysis of the MDO. Interestingly, we found that the lower the temperature of the reaction (T = 20 °C) and the higher the monomer addition flow rate, allowed the highest incorporation of MDO in the copolymer (up to 86 mol %). Unfortunately, the MDO incorporated in the closed formed (i.e., in the acetal form) and therefore, the acrylate copolymers produced did not contain ester groups in the backbone. Furthermore, increasing the MDO composition in the copolymers under the same polymerization conditions favored more hydrolysis than copolymerization and hence, incorporation content decreased. On the other hand, the ester size (2-octyl vs n-butyl) of the acrylate did not have any noticeable effect in the MDO incorporation content.

Improvement of thermal, mechanical, and electromagnetic interference shielding properties of polyethylene nanocomposites by introducing non‐covalently modified carbon nanotube and reactive polyethylene copolymer

AbstractWe herein report the enhancement of thermal, electrical, electromagnetic interference (EMI) shielding, and mechanical performance of polyethylene (PE) nanocomposites by the introduction of non‐covalently modified multi‐walled carbon nanotube (MWCNT) and ethylene‐glycidyl methacrylate (EGMA) copolymer. For this purpose, benzylacetic acid‐functionalized MWCNT (BA‐M) is prepared by ball milling, and it is melt‐mixed with EGMA to prepare a masterbatch. The masterbatch is then melt‐compounded with neat PE to manufacture a series of PE/EGMA/BA‐M nanocomposites with 0.5–5 wt% MWCNTs. Electron microscopic and spectroscopic analyses confirm the successful fabrication of non‐covalently functionalized BA‐M, the uniform dispersity of MWCNTs in the PE matrix, and the chemical reactions between the carboxylic acid groups of BA‐M and the epoxy group of EGMA in the nanocomposites. Scanning calorimetric data reveals that BA‐M acts as an efficient nucleating agent for the crystallization of PE. The excellent dispersity and robust interfacial bonding of BA‐M in the PE matrix result in improved electrical and EMI shielding properties in PE/EGMA/BA‐M nanocomposites. Furthermore, the tensile strength, initial modulus, and impact strength of the nanocomposites gradually rise as the BA‐M content increases. Thus, the PE/EGMA/BA‐M nanocomposite containing 5 wt% MWCNT achieves excellent performance of EMI shielding effectiveness of ~14.7 dB/mm, tensile strength of ~34.5 MPa, initial modulus of ~295.7 MPa, and impact strength of ~539.9 J/m, which represent enhancements of ~265%, ~40%, ~82%, and ~452%, respectively, compared to pristine PE.Highlights Non‐covalently modified MWCNT (BA‐M) was prepared by facile ball milling. PE nanocomposites with BA‐M and EGMA were prepared by masterbatch melt‐mixing. Excellent dispersity and interfacial bonding of MWCNT in the PE matrix were attained. Tensile strength and initial modulus of the nanocomposites were highly improved. EMI shielding effectiveness of the nanocomposite with 5 wt% MWCNT was ~14.7 dB/mm.

Acrylic acid incorporated nanocellulose/acrylamide ion-conductive hydrogels for wearable sensors

In this paper, CNC/PAM/PAA interpenetrating network composite hydrogels were prepared from acrylamide (AM), cellulose nanocrystals (CNC), and acrylic acid (AA) by in situ free radical polymerization. CNC/PAM/PAA-Ca2+ hydrogels were successfully prepared by adding CaCl2 to the mixed solution to introduce ions. The composite hydrogels were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy and tested for their mechanical, electrical, and sensing properties. The experimental results showed that the copolymerization reaction of AM and AA resulted in hydrogels with excellent mechanical properties, with a maximum tensile strength of 98.7 kPa and an elongation at break of 643.6%. In addition, the introduction of Ca2+ ions significantly improved the conductivity and sensitivity of the hydrogel. The developed multifunctional poly (AM-AA) hydrogels were able to stably detect the relative changes in electrical resistance during cyclic tensile, compressive, and bending motions of a human finger, which is expected to be widely used in flexible sensor devices.

Mechanically robust poly(urethane-imide) aerogels with excellent thermal insulation and sound absorption by ambient drying

Polyimide (PI) aerogels are the great candidates for sound absorption, thermal insulation and mechanical cushioning materials due to their low density, excellent mechanical properties and good thermal stability. However, the high shrinkage and hydrophilicity of PI aerogels, as well as the time-consuming and complexity of the process directly limit their wide application in many fields. Herein, a facile one-step method for the synthesis of porous monolithic poly(urethane-imide) (PUI) aerogels was successfully developed. Hydrothermal synthesis and ambient drying methods were adopted in the construction of monolithic chemically cross-linked PUI aerogels, which avoids the complex imidization process. PUI aerogels were homogeneously produced by a chemical cross-linking copolymerization reaction between polyurethane (PU) oligomers, Benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA) and 1, 3, 5-tris (6-isocyanatohexyl)-1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H)-trione without any catalysts. Interestingly, the introduction of linear flexible PU oligomers chain segments effectively prevented the shrinkage of the network backbone and enhanced the hydrophobicity of PUI aerogels. The obtained PUI aerogels have low density (0.196 g/cm3), low shrinkage (9.30%), high porosity (79.54%) and hydrophobicity (water contact angle of 129.2°). Under high pressure, PUI aerogel was compressed but not break and the compression Young's modulus as high as 3.638 MPa. Moreover, the thermal conductivity of PUI aerogels was only 59.92 mW/m/K at 150 °C. When the back cavity depth was 5 mm, the highest sound absorption coefficient of PUI aerogel was up to 0.7219. This work provides a new method for the development of lightweight, high-mechanical-strength polymer aerogels, and the prepared aerogels have a potential application in the field of multifunctional integrated sound absorption materials.

Restraining Lattice Oxygen Escape by Bioinspired Antioxidant Enables Thermal Runaway Prevention in Ni−Rich Cathode Based Lithium−Ion Batteries

AbstractNi−rich cathodes are hopeful materials for advanced lithium−ion batteries (LIBs) due to high capacity. Nonetheless, the chemical crosstalk triggered by reactive oxygen (O*) represents a critical factor in thermal runaway (TR). Currently, there are few effective means to prevent this parasitic reaction. Here, inspired by the O* scavenging effect of β−carotene in living organisms, it is innovatively identified that β−carotene can impede TR by restraining the escape of O* during the thermal decomposition of nickel−rich cathodes. Using LiNi0.6Co0.2Mn0.2O2 as model and extending to higher nickel content cathodes (LiNi0.8Co0.1Mn0.1O2, LiNi0.9Co0.05Mn0.05O2), it is demonstrated that β−carotene can undergo an in situ oxygen copolymerization reaction to trapping O*, thereby attenuating chemical crosstalk. Additionally, the generated oxygen copolymer can also adjust band center of the O 2p orbitals of delithiated cathode, alleviating the charge compensation behavior of oxygen anions, and thus delaying the phase transition of charged LiNi0.8Co0.1Mn0.1O2. As a result, the TR trigger temperature of NCM811∣Graphite pouch cell is increased from 131.0 to 195.0 °C and maximum temperature is reduced from 657.8 to 412.4 °C. This work introduces a new and simple strategy for designing functional additives to block TR, offering a promising avenue for advancing the safety of LIBs.

Target-Oriented Synthesis of Triphenylphosphine Functionalized Carbon Dots with Negative Charge for ROS Scavenging and Mitochondrial Targeting.

Triphenylphosphine functionalized carbon dots (TPP-CDs) showcase robust mitochondria targeting capacity owing to their positive electrical properties. However, TPP-CDs typically involve complicated synthesis steps and time-consuming postmodification procedures. Especially, the one-step target-oriented synthesis of TPP-CDs and the regulation of TPP linkage modes remain challenges. Herein, we propose a free-radical-initiated random copolymerization in combination with hydrothermal carbonation to regulate the TPP backbone linkage for target-oriented synthesis of triphenylphosphine copolymerization carbon dots (TPPcopoly-CDs). The linkage mechanism of random copolymerization reactions is directional, straightforward, and controllable. The TPP content and IC50 of hydroxyl radicals scavenging ability of TPPcopoly-CDs are 53 wt % and 0.52 mg/mL, respectively. TPP serves as a charge control agent to elevate the negatively charged CDs by 20 mV. TPPcopoly-CDs with negative charge can target mitochondria, and in the corresponding mechanism the TPP moiety plays a crucial role in targeting mitochondria. This discovery provides a new perspective on the controlled synthesis, TPP linkage modes, and mitochondrial targeting design of TPP-CDs.