Bridged Bicyclic Lactam Enables Chemically Recyclable Nylon.

Nylon, a widely-used high-performance thermoplastic, boasts exceptional durability and resistance to various solvents and weak acids, making it indispensable across diverse applications. However, its nonbiodegradable nature has led to alarming environmental pollution in land and oceans. Chemical recycling to monomers (CRM) stands as a crucial strategy for establishing a circular plastic economy, but the CRM of nylon remains largely unexplored. Herein, we introduce the bridged bicyclic lactam 5-azabicyclo[2.2.1]octan-6-one (5/6-LM), evolved from δ-valerolactam and pyrrolidone, to solve the trade-off in depolymerizability and performance. Notably, 5/6-LM exhibits nearly 95 % conversion in mild polymerization conditions and efficient depolymerization catalyzed by lewis acids. This compound is synthetically accessible from commercially available chemicals in a single step at room temperature, demonstrating high efficiency and scalability up to 50 g in laboratory. Furthermore, the resulting polyamide displays remarkable attributes including high crystallinity and thermostability up to 283 °C, significantly broadening the scope of chemically recyclable nylons.

Oxygen-Tolerant Near-Infrared Organic Long-Persistent Luminescent Copolymers.

Organic materials exhibiting long-lasting emission in the near infrared are expected to have applications in bio-imaging and other areas. Although room temperature phosphorescence and thermally activated delayed fluorescence display long-lived emission of approximately one minute, organic long-persistent luminescence (OLPL) systems with a similar emission mechanism to inorganic persistent emitters can emit for several hours at room temperature. In particular OLPL with a hole-diffusion mechanism can function even in the presence of oxygen. However, ionic materials lack long-term stability in neutral organic host owing to aggregation and phase separation. In this study, we synthesized polymers with stable near-infrared persistent luminescence at room temperature via the copolymerization of electron donors and acceptors. The copolymers exhibit long-persistent luminescence (LPL) at temperatures below the glass transition temperature and can be excited by approximately the entire range of visible light. LPL properties and spectra can be controlled by the dopant.

Mechanistic Insight into Anion-Binding Catalytic Living Cationic Polymerization.

Exploiting non-covalent interactions to catalyze challenging ionic polymerizations is an ambitious goal but is in its infancy. We recently demonstrated non-covalent anion-binding catalysis as an effective methodology to enable living cationic polymerization (LCP) of vinyl ethers in an environmentally benign manner. Here, we further elucidate the structure-reactivity relationships of the elaborately designed seleno-cyclodiphosph(V)azanes catalysts and the roles of anion-binding interactions by a combined theoretical DFT study and experimental study. The investigation suggests that the distinct cis-cyclodiphosph(V)azane framework combined with "selenium effect" and electron-withdrawing 3,5-(CF3 )2 -Phenyl substitution pattern in catalyst enables a critical contribution to accessing excellent stability, anion affinity and solubility under polymerization conditions. Thus, the catalyst could leverage anion-binding interactions to precisely control reversible and transient dormant-active species equilibrium, allowing it to dynamically bind, recognize and pre-organize propagating ionic species and monomer, thereby facilitating efficient chain propagation and minimizing irreversible chain transfer events under mild conditions. The more in-depth understanding of the mechanism for anion-binding catalytic LCP reported herein should help to guide future catalyst design and to extend this concept to broader polymerization systems where ionic species serve as crucial intermediates.

Performance-Advantaged Stereoregular Recyclable Plastics Enabled by Aluminum-Catalytic Ring-Opening Polymerization of Dithiolactone.

Chemically recyclable polymers that can depolymerize into their constituent monomers are attractive candidates to replace non-recyclable petroleum-derived plastics. However, the physical properties and mechanical strengths of depolymerizable polymers are commonly insufficient for practical applications. Here we demonstrate that by proper ligand design and modification, aluminum complexes can catalyse stereoretentive ring-opening polymerization of dithiolactone, yielding highly isotactic polythioesters with molar masses up to 45.5 kDa. This material can form crystalline stereocomplex with a Tm of 94.5 °C, and exhibits mechanical performances comparable to petroleum-based low density polyethylene. Exposure of the polythioester to aluminum precatalyst used to synthesized it resulted in depolymerization to pristine chiral dithiolactone. Experimental and computational studies suggest that aluminum complexes have appropriate binding affinity with sulfide propagating species, thereby avoiding catalyst poisoning and minimizing epimerization reactions, which has not been accessible using other metal catalysts. Overall, aluminum catalysis provides access to performance-advantaged stereoregular recyclable plastics as a promising alternative to petrochemical plastics, thus incentivizing improved plastic sustainability.

Initiator-free in-situ synthesized polymer electrolytes with high ionic conductivity for dendrite-free lithium metal batteries.

In-situ preparation of polymer electrolytes (PEs) can enhance electrolyte/electrode interface contact and accommodate the current large-scale production line of lithium-ion batteries (LIBs). However, reactive initiators of in-situ PEs may lead to low capacity, increased impedance and poor cycling performance. Flammable and volatile monomers and plasticizers of in-situ PEs are potential safety risks for the batteries. Herein, we adopt lithium difluoro(oxalate)borate (LiDFOB)-initiated in-situ polymerization of solid-state non-volatile monomer 1,3,5-trioxane (TXE) to fabricate PEs (In-situ PTXE). Fluoroethylene carbonate (FEC) and methyl 2,2,2-trifluoroethyl carbonate (FEMC) with good fire retardance, high flash point, wide electrochemical window and high dielectric constant were introduced as plasticizers to improve ionic conductivity and flame retardant property of In-situ PTXE. Compared with previously reported in-situ PEs, In-situ PTXE exhibits distinct merits, including free of initiators, non-volatile precursors, high ionic conductivity of 3.76 × 10-3 S cm-1, high lithium-ion transference number of 0.76, wide electrochemical stability window (ESW) of 6.06 V, excellent electrolyte/electrode interface stability and effectively inhibition of Li dendrite growth on the lithium metal anode. The fabricated LiFePO4 (LFP)/Li batteries with In-situ PTXE achieve significantly boosted cycle stability (capacity retention rate of 90.4% after 560 cycles) and outstanding rate capability (discharge capacity of 111.7 mAh g-1 at 3C rate).

Precision Synthesis of Polypeptides via Living Anionic Ring-Opening Polymerization of N-Carboxyanhydrides by Tri-thiourea Catalysts.

The chemistry of α-amino acid N-carboxyanhydrides (NCAs) has a history of over 100 years, but precise and efficient ring-opening polymerization methods for NCAs remain highly needed to facilitate the studies of polypeptides─that is, mimics of natural proteins─in various disciplines. Moreover, the universally accepted NCA polymerization mechanisms are largely limited to the "amine" and the "activated monomer" mechanisms, and the anionic ring-opening polymerization of NCAs has so far not been invoked. Herein, we show an unprecedented anion-binding catalytic system combining tripodal tri-thiourea with sodium thiophenolate that enables the fast and selective anionic ring-opening polymerization of NCAs. This method leads to the precision construction of various polypeptides with living polymerization behavior and is evidenced by narrow molecular weight distributions (Mw/Mn < 1.2), chain extension experiments, and minimal "activated monomer" pathway. Calculations and experimental results elucidate a living anionic polymerization mechanism, and high selectivities for monomer propagation relative to other deleterious side reactions, such as the "activated monomer" pathway, are attributed to the enhanced stabilization of the propagating carbamate anion, which is enforced by an intramolecular hydrogen bond within the tri-thiourea structure.

Tug-of-War between Two Distinct Catalytic Sites Enables Fast and Selective Ring-Opening Copolymerizations.

Ring-opening copolymerizations have emerged as a powerful approach towards the creation of sustainable polymers. Typical H-bonding catalysts for ring-opening are subject to a single catalytic site. Here we describe a H-bond-donor/Lewis-acidic-boron organocatalyst featuring two distinct catalytic sites in one molecule. The ring-opening copolymerization of epoxides with anhydride mediated by these modular, and tunable catalysts achieves high selectivity (>99 % polyester selectivity) and markedly higher activity compared to either of the di-thiourea analogues or any combinations of them. Calculations and experimental studies reveal that the superior catalytic performance arises from tug-of-war between two differentiated catalytic sites: thiourea pulls off the propagating chain-end from boron center, simultaneously enhancing the role of monomer activation and also nucleophilicity of the propagation intermediates.

Surface Functionalization of SBA-15 for Immobilization of Myoglobin.

Mesoporous molecular sieve SBA-15 was successfully modified with 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTMS). The functionalized SBA-15 were characterized by small-angle X-ray (SAXRD), thermogravimetric analysis (TG), N2 adsorption, and Fourier transformed infrared spectrum (FT-IR). APTES functionalized SBA-15 (named SBA-15-A) and GPTMS functionalized SBA-15 (named SBA-15-G) were used to immobilize myoglobin (Mb). The loading amounts of Mb by SBA-15-A and SBA-15-G were 511.2 and 547.8 mg/g, respectively, whereas only 359.6 mg/g was achieved by SBA-15. Mb/SBA-15-G and Mb/SBA-15-A demonstrated better reusability than SBA-15, retaining 84.6% and 82.7% of the initial activity after repeated use seven times. The Mb/SBA-15-A and Mb/SBA-15-G also exhibited improved thermal stability and storage stability.

Protein Engineering of an Artificial P450BM3 Peroxygenase System Enables Highly Selective O-Demethylation of Lignin Monomers.

The O-demethylation of lignin monomers, which has drawn substantial attention recently, is critical for the formation of phenols from aromatic ethers. The P450BM3 peroxygenase system was recently found to enable the O-demethylation of different aromatic ethers with the assistance of dual-functional small molecules (DFSM), but these prepared mutants only have either moderate O-demethylation activity or moderate selectivity, which hinders their further application. In this study, we improve the system by introducing different amino acids into the active site of P450BM3, and these amino acids with different side chains impacted the catalytic ability of enzymes due to their differences in size, polarity, and hydrophobicity. Among the prepared mutants, the combination of V78A/F87A/T268I/A264G and Im-C6-Phe efficiently catalyzed the O-demethylation of guaiacol (TON = 839) with 100% selectivity. Compared with NADPH-dependent systems, we offer an economical and practical bioconversion avenue.

Switchable Polymerization Organocatalysis: From Monomer Mixtures to Block Copolymers.

One-pot production of sequence-controlled block copolymer from mixed monomers is a crucial but rarely reached goal. Using a switchable Lewis-pair organocatalyst, we have accomplished sequence-selective polymerization from a mixture of O-carboxyanhydride (OCA) and epoxide. Polymerization of the OCA monomer occurs first and exclusively because of its exceedingly high polymerizability. When OCA is fully consumed, alternating copolymerization of epoxide and CO2 liberated in OCA polymerization is triggered from the termini of the first block. The two polymerizations thus occur in tandem, both in chemoselective fashion, so that a sequence-controlled block polymer with up to 99 % CO2 conversion is furnished in this one-pot protocol. Calculations and experimental results demonstrate a chemoselective and cooperative mechanism, where the high polymerizability of the OCA monomers guarantees exquisite sequence selectivity and the cooperative decarboxylation partly arose from the stabilization effect by triethylborane, which facilitates the smooth transformation of the chain end from carbonate to alkoxide.

Iterative Synthesis of Stereo- and Sequence-Defined Polymers via Acid-Orthogonal Deprotection Chemistry.

Absolute control over polymer stereo- and sequence structure is highly challenging in polymer chemistry. Here, an acid-orthogonal deprotection strategy is proposed for the iterative synthesis of a family of unimolecular polymers starting with enantiopure serines, featuring precise sequence, stereoconfiguration and side-chain functionalities that cannot be achieved using traditional polymerization techniques. Acid-orthogonal deprotections proceed independently of one another by the selection of protecting groups that feature the respective acid-lability. Under p-toluenesulfonic acid, acidolysis of tert-butyloxycarbonyl can proceed exclusively, while low-dosage trifluoroacetic acid and low temperature only trigger the selective and quantitative cleavage of trityl. The pioneering use of this acid-orthogonal deprotection chemistry increases the compatibility with otherwise sensitive groups and opens up pathways to facilely introduce structural and functional diversity into stereo- and sequence-defined polymers, thus imparting their unique properties beyond natural biopolymers.

The simulation dataset of each model for the circle antipode experiment.

This dataset includes trajectory data and video data produced by different models (including the traditional social force model, the Voronoi-based detour social force model and double-layer detour decision model) simulating the circle antipode experiment. During the simulation process, the coordinates of each pedestrian in each simulation step are recorded to form trajectory data, and each frame is recorded to form simulation video data. This data can provide an intuitive gap in the description of pedestrian detour behaviour among these pedestrian simulation models, and can be used as the comparative data when modify model to better describe pedestrian detour behaviour in the circle antipode experiment.

O-to-S Substitution Enables Dovetailing Conflicting Cyclizability, Polymerizability, and Recyclability: Dithiolactone vs. Dilactone.

Developing chemically recyclable polymers represents a greener alternative to landfill and incineration and offers a closed-loop strategy toward a circular materials economy. However, the synthesis of chemically recyclable polymers is still plagued with certain fundamental limitations, including trade-offs between the monomer's cyclizability and polymerizability, as well as between polymer's depolymerizability and properties. Here we describe the subtle O-to-S substitution, dithiolactone monomers derived from abundant feedstock α-amino acids can demonstrate appealing chemical properties different from those of dilactone, including accelerated ring closure, augmented kinetics polymerizability, high depolymerizability and selectivity, and thus constitute a unique class of polythioester materials exhibiting controlled molecular weight (up to 100.5 kDa), atactic yet high crystallinity, structurally diversity, and chemical recyclability. These polythioesters well addresses the formidable challenges of developing chemically recyclable polymers by having an unusual set of desired properties, including easy-to-make monomer from ubiquitous feedstock, and high polymerizability, crystallinity and precise tunability of physicochemical performance, as well as high depolymerizability and selectivity. Computational studies explain why O-to-S modification of polymer backbone enables dovetailing desirable, but conflicting, performance into one polymer structure.

HPLC-MS and Network Pharmacology Analysis to Reveal Quality Markers of Huo-Xue-Jiang-Tang Yin, a Chinese Herbal Medicine for Type 2 Diabetes Mellitus.

Huo-Xue-Jiang-Tang Yin (HXJTY) is a Chinese medicine formulation, which has been widely used for the treatment of various lipometabolism- and glycometabolism-related diseases in clinics. Currently, HXJTY is mainly prescribed to treat patients with type 2 diabetes mellitus (T2DM), yet its chemical and pharmacologic profiles remain to be elucidated. Here, the potential bioactive compound and action mechanism were investigated using chemical and network pharmacology analysis. A rapid HPLC-MS was employed to identify and quantify the component of HXJTY. On the basis of the identified chemical markers from HXJTY, a network pharmacology study, including target gene prediction and functional enrichment, was applied to screen out the main quality markers of HXJTY and explore its potential mechanism for the treatment of T2DM. The results showed that a total of 22 components were identified and quantified from HXJTY by HPLC-MS. Furthermore, 12 active components such as astragaloside IV, calycosin-7-O-ß-D-glucoside, hydroxysafflor yellow A, and others were proposed as quality markers of HXJTY for treating T2DM based on network pharmacology analysis. In addition, 125 corresponding possible therapeutic target genes of T2DM were obtained. These target genes are mainly related to peptidase activity, hydrolase activity, phosphatase activity, and cofactor binding, suggesting the involvement of PI3K-Akt, MAPK, AGE-RAGE, and Rap1 signaling pathways in HXJTY-treated T2DM. Our results may provide a useful approach to identify potential quality markers and molecular mechanism of HXJTY for treating T2DM.

S-Carboxyanhydrides: Ultrafast and Selective Ring-Opening Polymerizations Towards Well-defined Functionalized Polythioesters.

Aliphatic polythioesters are popular polymers because of their appealing performance such as metal coordination ability, high refractive indices, and biodegradability. One of the most powerful approaches for generating these polymers is the ring-opening polymerization (ROP) of cyclic monomers. However, the synthesis of precisely controlled polythioesters via ROP of thiolactones still faces formidable challenges, including the minimal functional diversity of available thiolactone monomers, as well as inevitable transthioesterification side reactions. Here we introduce a hyperactive class of S-carboxyanhydride (SCA) monomers derived from amino acids that are significantly more reactive than thiolactones for ultrafast and selective ROP. Inclusion of the initiator PPNOBz ([PPN]=bis(triphenylphosphine)-iminium) with chain transfer agent benzoic acid, the polymerizations that can be operated in open vessels reach complete conversion within minutes (1-2 min) at room temperature, yielding polythioesters with predictable molecular weight, low dispersities, retained stereoregularity and chemical recyclability. Most fascinating are the functionalized SCAs that allow the incorporating of functional groups along the polythioester chain and thus finely tune their physicochemical performance. Computational studies were carried out to explore the origins of the distinctive rapidity and exquisite selectivity of the polymerizations, offering mechanistic insight and explaining why high polymerizability of SCA monomer is able to facilitate exquisitely selective ring-opening for enchainment over competing transthioesterification and backbiting reactions.

Effects of Pore Size and Crosslinking Methods on the Immobilization of Myoglobin in SBA-15.

A series of stable mesoporous silica sieves (SBA-15) with different pore sizes (9.8, 7.2, and 5.5 nm) were synthesized using a hydrothermal method. The resulting mesoporous material was then utilized for protein immobilization using myoglobin (Mb) as the target protein. The effects of pore size and adsorption methods on the immobilization efficiency of Mb in a mesoporous material were studied. The SBA-15 with a pore size of 7.2 nm showed the best loading capacity, reaching 413.8 mg/g. The SBA-15 with a pore size of 9.8 nm showed the highest retained catalytic ability (92.36%). The immobilized enzyme was more stable than the free enzyme. After seven consecutive assay cycles, Mb adsorbed by SBA-15 (Mb/SBA-15) and Mb adsorbed by SBA-15 and crosslinked with glutaraldehyde (Mb/G/SBA-15) retained 36.41% and 62.37% of their initial activity, respectively.

Co-Construction of Sulfur Vacancies and Heterojunctions in Tungsten Disulfide to Induce Fast Electronic/Ionic Diffusion Kinetics for Sodium-Ion Batteries.

Engineering novel electrode materials with unique architectures has a significant impact on tuning the structural/electrochemical properties for boosting the performance of secondary battery systems. Herein, starting from well-organized WS2 nanorods, an ingenious design of a one-step method is proposed to prepare a bimetallic sulfide composite with a coaxial carbon coating layer, simply enabled by ZIF-8 introduction. Rich sulfur vacancies and WS2 /ZnS heterojunctions can be simultaneously developed, that significantly improve ionic and electronic diffusion kinetics. In addition, a homogeneous carbon protective layer around the surface of the composite guarantees an outstanding structural stability, a reversible capacity of 170.8 mAh g-1 after 5000 cycles at a high rate of 5 A g-1 . A great potential in practical application is also exhibited, where a full cell based on the WS2- x /ZnS@C anode and the P2-Na2/3 Ni1/3 Mn1/3 O2 cathode can maintain a reversible capacity of 89.4 mAh g-1 after 500 cycles at 1 A g-1 . Moreover, the underlying electrochemical Na storage mechanisms are illustrated in detail by theoretical calculations, electrochemical kinetic analysis, and operando X-ray diffraction characterization.

Highly Efficient Non-Nucleophilic Mg(CF3SO3)2-Based Electrolyte for High-Power Mg/S Battery.

The application of high-energy Mg/S batteries was obstructed by the insufficiency of low-cost and non-nucleophilic electrolyte. In this work, a non-nucleophilic electrolyte was prepared by facilely dissolving Mg(CF3SO3)2, MgCl2, and AlCl3 in 1,2-dimethoxyethane (DME). The equilibrium species of the MTB electrolyte mainly comprise [Mg2(µ-Cl)2(DME)4]2+ and [(CF3SO3)AlCl3]-, which are generated by dehalodimerization reaction and Lewis acid-base reaction, respectively. The electrolyte exhibits a highly efficient reversible Mg deposition/dissolution, low overpotential of around 250 mV, and good oxidative stability up to 3.5 V after conditioning. The conditioning process that the active [Mg2(µ-Cl)2(DME)4]2+ species transforms into [Mg3(µ3-Cl)(µ2-Cl)2(DME)7]3+ was demonstrated, owing to the irreversible deposition of Al3+ on Mg foil. More importantly, this electrolyte exhibited good compatibility and kinetics for reversible Mg/MgSx redox, resulting in a high specific capacity of 866 mAh g-1 at 200 mA g-1 and high power density of 550 W kg-1. This work offers a new direction for low-cost, non-nucleophilic electrolyte and paves the way to explore high-power Mg/S batteries.

Synergetic Organocatalysis for Eliminating Epimerization in Ring-Opening Polymerizations Enables Synthesis of Stereoregular Isotactic Polyester.

Ring-opening polymerization of O-carboxyanhydrides (OCAs) can furnish polyesters with a diversity of functional groups that are traditionally hard to harvest by polymerization of lactones. Typical ring-opening catalysts are subject to unavoidable racemization of most OCA monomers, which hampers the synthesis of highly isotactic crystalline polymers. Here, we describe an effective bifunctional single-molecule organocatalysis for selective ring-opening polymerization of OCAs without epimerization. The close vicinity of both activating groups in the same molecule engenders an amplified synergetic effect and thus allows for the use of mild bases, thereby leading to minimal epimerization for polymerization. Ring-opening polymerization of manOCA monomer (OCA from mandelic acid) mediated by the bifunctional single-molecule organocatalyst yields highly isotactic poly(mandelic acid) (PMA) with controlled molecular weights (up to 19.8 kg mol-1). Mixing of the two enantiomers of PMA generates the first example of a crystalline stereocomplex in this area, which displayed distinct Tm values around 150 °C. Remarkably, the bifunctional catalysts are moisture-stable, recyclable, and easy to use, allowing sustainable and scalable synthesis of a stereoregular functional polyester.

Effect of postoperative systemic antipsychotic therapy on psychiatric recurrence in patients with meningiomas.

A number of patients with meningiomas and psychiatric disorders will suffer psychiatric symptom recurrence following tumorectomies. The present study reported a retrospective analysis regarding 42 cases of patients with meningiomas using complete clinical follow-up data from June 2005 to June 2013. The patients were divided into the systemic antipsychotic (SP) group (n=20) following 6months of postoperative SP therapy and the none-SP (NSP) group (n=22), who did not receive postoperative antipsychotic treatment. Patients were assessed using the Positive and Negative Syndrome Scale (PANSS) and Brief Psychiatric Rating Scale (BPRS) at the time points of prior to surgery, immediately following surgery, and 6 months, 12 months and 3 years following surgery. The effective rate, recurrence rate, rehospitalization rate and survival analysis were calculated. The BPRS score and PANSS scores (including PANSS positive, PANSS negative, PANSS general psychopathology and PANSS overall) in the SP group at 6 months, 12 months and 3 years following surgery were significantly decreased compared with the NSP group (P<0.05). The effective rate was 95, 90 and 90% at 6 months, 12 months and 3 years, respectively, in the SP group, whilst it was 68.2, 63.6 and 59%, respectively, in the NSP group, which was statistically significant (χ2=4.89, χ2=4.01 and χ2=5.12; P<0.05). The recurrence rate of the SP group was 0, 5 and 10% at 6 months, 12 months and 3 years, respectively, whilst in the NSP group it was 22.7, 31.8 and 54.5%, respectively, which was statistically significant (χ2=5.16, χ2=4.89 and χ2=9.34; P<0.05). The rehospitalization rate of the SP group was 0, 0 and 5% at 6 months, 12 months and 3 years, respectively, whilst in the NSP group it was 13.6, 22.7 and 36.4%, respectively, and the data at 12 months and 3 years was statistically significant (χ2=5.16 and χ2=6.12; P<0.05). Kaplan-Meier survival analysis indicated that the accumulative survival rates of recurrence and rehospitalization in the SP group were improved compared with the NSP group. The log-rank of recurrence was χ2=9.369 (P=0.002) and the log-rank of rehospitalization was χ2=6.330 (P=0.012). In conclusion, postoperative SP therapy is of great importance to the consolidation of mental symptoms in patients with meningiomas and psychiatric symptoms, and it may significantly reduce the recurrence and rehospitalization rates.