Construction of Polycarbonates with Pendant Multifunctional Groups via a One-Step CO2/ Diepoxide Copolymerization Approach.

A "one-step" strategy has been demonstrated for the tunable synthesis of multifunctional aliphatic polycarbonates (APCs) with ethylene oxide (EO), ethylene carbonate (EC), and cyclohexene oxide (CHO) side groups by the copolymerization of 4-vinyl-1-cyclohexene diepoxide with carbon dioxide under an aminotriphenolate iron/PPNBz (PPN = bis(triphenylphosphine)-iminium, Bz = benzoate) binary catalyst. By adjusting the PPNBz-to-iron complex ratio and incorporating auxiliary solvents, the content of functional side groups can be tuned within the ranges of 53-75% for EO, 18-47% for EC, and <1-7% for CHO. The yield and molecular weight distribution of the resulting multifunctional APCs are affected by the viscosity of the polymerization system. The use of tetrahydrofuran as an auxiliary solvent enables the preparation of narrow-distribution polycarbonates at high conversion. This work presents a novel perspective for the preparation of tailorable multifunctional APCs.

Synthesis of α-Diimine Complex Enabling Rapidly Covalent Attachment to Silica Supports and Application of Homo-/Heterogeneous Catalysts in Ethylene Polymerization.

For covalent attachment-supported α-diimine catalysts, on the basis of ensuring the thermal stability and activity of the catalysts, the important problem is that the active group on the catalyst can quickly react with the support, anchoring it firmly on the support, shortening the loading time, reducing the negative impact of the support on the active centers, and further improving the polymer morphology, which makes them suitable for use in industrial polymerization temperatures. Herein, we synthesized a α-diimine nickel(II) catalyst bearing four hydroxyl substituents. The hydroxyl substituents enable the catalyst to be immobilized firmly on silica support by covalent linkage in 5-10 min. Compared with the toluene solvent system, the homogeneous catalysts show high activity and thermal stability in hexane solvent at the same conditions. Compared with homogeneous catalysts, heterogeneous catalysis leads to improvements in catalyst lifetime, polymer morphology control, catalytic activity, and the molecular weight of polyethylene (up to 679 kg/mol). The silica-supported catalysts resulted in higher melting temperatures as well as lower branching densities in polyethylenes. Even at 70 °C, the polyethylene prepared by S-CatA-2 still exhibits dispersed particle morphology, and there is no phenomenon of reactor fouling, which is suitable for industrial polymerization processes.

Emission accounting and drivers in Central Asian countries.

Emerging countries are at the frontier of climate change actions, and carbon emissions accounting provides a quantifiable measure of the environmental impact of economic activities, which allows for comparisons of emissions across different entities. However, currently there is no study covering detailed emissions inventories for emerging countries in Central Asian. This paper compiles detailed and accurate carbon emissions inventories in several Central Asian countries (i.e., Kazakhstan, Kyrgyzstan, Pakistan, Palestine, Tajikistan, and Uzbekistan) during the period 2010-2020. Using the IPCC administrative territorial approach, we for the first time compile their emissions inventories in 47 economic sectors and five energy categories. Moreover, we also investigate decoupling status based on Tapio decoupling model and examine emissions driving factors based on the index decomposition analysis method. The primary results illustrate that carbon emissions in Central Asian countries are increasing with huge differences. Decoupling results highlight that most of the sample countries still need more effort to decouple the economy and emissions except that Pakistan achieves an ideal strong decoupling state. The results of the decomposition indicate that the economy and population both raise emissions, while energy intensity and carbon intensity are negative drivers in some countries. We propose practical policy implications for decarbonization and energy transition roadmap in Central Asian countries.

Crystallization and melting of unentangled poly(ε-caprolactone) cycles containing pendants.

The Rouse model provides a basic framework to understand the chain dynamics of polymers, which is confirmed to be more suitable for exploring the linear dynamics of unentangled polymers. The crystalline morphology governed by chain dynamics and crystallization kinetics is expected to differ in linear and cyclic polymers. Cyclic poly(ε-caprolactone)s (c-PCLs) containing two bi-anthracenyl group pendants with molecular weights close to the critical molecular weight (Mc) were synthesized to investigate the chain dynamics based crystallization and melting behavior by DSC, POM, and in situ simultaneous small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) investigations during heating of the isothermally crystallized samples. Double endothermic peaks were observed in the DSC curves with a low heating rate of c-PCLs without entanglement after isothermal crystallization, especially for c-PCLs with Mc. The structure evolution of the crystalline structures observed from the in situ investigations during the heating and double endothermic peaks in DSC heating curves of the c-PCLs indicate the role of pendants in the chain dynamics, which leads to the reorganization of the metastable structures. Banded spherulites of c-PCL without entanglement were observed for the first time, and the uneven growth of spherulites along the radial direction may be caused by the mismatch between chain dynamics and crystallization kinetics.

Mpemba effect in crystallization of polybutene-1.

The Mpemba effect and its inverse can be understood as a result of nonequilibrium thermodynamics. In polymers, changes of state are generally non-equilibrium processes. However, the Mpemba effect has been rarely reported in the crystallization of polymers. In the melt, polybutene-1 (PB-1) has the lowest critical cooling rate in polyolefins and tends to maintain its original structure and properties with thermal history. A nascent PB-1 sample was prepared by using metallocene catalysis at low temperature, and the crystallization behavior and crystalline structure of the PB-1 were characterized by DSC and WAXS. Experimentally, a clear Mpemba effect is observed not only in the crystallization of the nascent PB-1 melt in form II but also in form I obtained from the nascent PB-1 at low melting temperature. It is proposed that this is due to the differences in the chain conformational entropy in the lattice which influence conformational relaxation times. The entropy and the relaxation time can be predicted using the Adam-Gibbs equations, whereas non-equilibrium thermodynamics is required to describe the crystallization with the Mpemba effect.

Effects of end groups and entanglements on crystallization and melting behaviors of poly(ε-caprolactone).

The topology including end groups, entanglement loops, and tie molecules has a significant impact on the rheological and crystallization behavior and consequently on the functionality of a polymer. Unentangled, weakly entangled, and strongly entangled poly(ε-caprolactone)s (PCLs) with end groups and various molecular weights were synthesized. POM and DSC were used to observe spherulite growth and characterize thermal properties during crystallization and melting. The viscosity and structure of the samples were probed by rheology and X-ray analysis, respectively. The crossover of the scaling relationship of viscosity vs molecular weight demonstrates that the samples cover a wide range of entanglement density, and the bulky end groups cause deviations from the classical scaling laws. In situ simultaneous SAXS/WAXS investigations showed that the crystal structure of PCLs did not change with end groups and heating. The results of POM and DSC imply that the end groups and entanglements affect the crystallization rate and the spherulite morphology. The melting of PCLs containing end groups was found to be a multi-step process involving various nanoscale crystalline structures. The evolution of nanoscale crystalline structures of isothermally crystallized PCLs during heating was analyzed by fitting 1D SAXS profiles, and the continuous structural evolution was found to be a process influenced by end groups and entanglements. The results show that end groups and entanglements affect the chain dynamics and lead to constrained crystallization behavior and the formation of metastable structures, ultimately affecting the structure evolution during melting.

Nucleophilic ring-opening of thiocyclic carbonates: A scheme to prepare sulfhydryl-rich binders for high-performance lithium-sulfur batteries.

Problems such as cathode collapse caused by volume change and shuttle effect of lithium polysulfides (LiPSs) limit the commercialization of Lithium-Sulfur (Li-S). Herein, we developed a sulfhydryl-containing multifunctional binder prepared by the nucleophilic ring-opening reaction of thiocyclic carbonates with amino groups. The binders (CNP-T and CNP-F) form sulfur-containing polymers with sulfur through the wet-slurry process, thereby effectively suppressing the shuttle effect. The abundant polar functional groups (e.g., -NH2, -CS(NH)-) in CNP-T and CNP-F can effectively adsorb LiPSs to weaken the shuttle effect, which is confirmed by both density functional theory (DFT) and experimental results. At the same time, their own hyperbranched network structure can also limit the volume change of the sulfur cathode. Therefore, the Li-S battery exhibits an initial specific capacity of 924.02 mAh/g and a decay rate of 0.033% when cycled at 1C for 500 cycles.

Emission growth and drivers in Mainland Southeast Asian countries.

Mainland Southeast Asian (MSEA) countries (Cambodia, Laos, Thailand, Myanmar, and Vietnam) are likely to become one of the next hotspots for emission reduction, since CO2 emissions in this area will have a two-thirds increase by 2040 due to rapid economy growth and associated energy consumption. As one of the most vulnerable areas to climate change, MSEA countries need to develop low-carbon roadmaps based on accurate emission data. This study provides emission inventories for MSEA countries for 2010-2019, based on the IPCC territorial emission accounting approach , including emissions from five types of fuels (i.e., coal, crude oil, oil products, natural gas, and biofuels & waste) used in 47 economic sectors. The results show that the emissions in MSEA countries are on the rise, with average annual growth rates ranging from 2.5% in Thailand to 19.3% in Laos. Biomass is one of the most important sources of carbon emissions, contributing between 11.8% and 76.7% of total carbon emissions, but its share has been declining in most countries, whereas the share of emissions from coal has risen sharply in Laos, Vietnam, and Cambodia. We further examine the drivers behind the changes in emissions using index decomposition analysis. Economic growth was the strongest driver of growth in emissions, while population growth has only had a small effect on emission growth. Energy intensity varies widely across nations, but only significantly reduced CO2 emission growth in Thailand. The secondary sector considerable contributed to an increase in CO2 emissions in Laos and Vietnam, while the tertiary sector only moderately contributed to emissions in Thailand. Our study provides a better understanding of the composition and underlying factors of emission growth in MSEA countries, this could shape their low-carbon development pathway. Our results could also inform other emerging economies, which may become emission hotspots in the next decades, to develop low-carbon roadmaps, thereby contributing to the achievement of global climate change targets.

High-Entropy Microdomain Interlocking Polymer Electrolytes for Advanced All-Solid-State Battery Chemistries.

All-solid-state polymer electrolytes (ASPEs) with excellent processivity are considered one of the most forward-looking materials for large-scale industrialization. However, the contradiction between improving the mechanical strength and accelerating the ionic migration of ASPEs has always been difficult to reconcile. Herein, a rational concept is raised of high-entropy microdomain interlocking ASPEs (HEMI-ASPEs), inspired by entropic elasticity well-known in polymer and biochemical sciences, by introducing newly designed multifunctional ABC miktoarm star terpolymers into polyethylene oxide for the first time. The tailor-made HEMI-ASPEs possess multifunctional polymer chains, which induce themselves to assemble into micro- and nanoscale dynamic interlocking networks with high topological structure entropy. HEMI-ASPEs achieve excellent toughness, considerable ionic conductivity, an appreciable lithium transference number (0.63), and desirable thermal stability (Td  > 400 °C) for all-solid-state lithium metal batteries. The Li|HEMI-ASPE-Li|Li symmetrical cell shows a stable Li plating/stripping performance over 4000 h, and a LiFePO4 |HEMI-ASPE-Li|Li full cell exhibits a high capacity retention (≈96%) after 300 cycles. This work contributes an innovative design concept introducing high-entropy supramolecular dynamic networks for ASPEs.

Construction of Bio-Based Polyurethanes via Olefin Metathesis and Their Thermal Reversible Behavior.

With the increase in awareness of environmental protection and the shortage of oil resources, bio-based polyurethane has attracted increasing attention due to its ecological friendliness, low cost and easy degradation. In this paper, using Eugenol (Eug) derived from plant essential oils as the raw resource, syringyl ethanol (Syol) was prepared, and three monomers were obtained by the reaction of the Eug or Syol with Hexamethylene diisocyanate (HDI)or 4,4'-methylene di (phenyl isocyanate) (MDI), respectively. Then, three novel bio-based polyurethanes, P(Eug-HDI), P(Syol-HDI) and P(Syol-MDI), were synthesized by olefin metathesis polymerization. The effects of the catalyst type, reaction solvent, reaction temperature, reaction time, molar ratio of catalyst dosage and metal salts on the Eug-HDI olefin metathesis polymerization were investigated in detail. Under the optimal conditions, the yield reached 64.7%. It is worth noting that the addition of metal Ni salts could significantly promote the polymerization, in which NiI2 could increase the yield to 86.6%. Furthermore, the thermal decomposition behaviors of these bio-based polyurethanes were explored by DSC and variable temperature infrared spectroscopy. The test results showed that P(Eug-HDI) had a reversible thermal decomposition and a certain self-healing performance. This paper provided a new method for the preparation of bio-based polyurethane.

Slurry Homopolymerization of Ethylene Using Thermostable α-Diimine Nickel Catalysts Covalently Linked to Silica Supports via Substituents on Acenaphthequinone-Backbone.

Four supported α-diimine nickel(II) catalysts covalently linked to silica via hydroxyl functionality on α-diimine acenaphthequinone-backbone were prepared and used in slurry polymerizations of ethylene to produce branched polyethylenes. The catalytic activities of these still reached 106 g/molNi·h at 70 °C. The life of the supported catalyst is prolonged, as can be seen from the kinetic profile. The molecular weight of the polyethylene obtained by the 955 silica gel supported catalyst was higher than that obtained by the 2408D silica gel supported catalyst. The melting points of polyethylene obtained by the supported catalysts S-C1-a/b are all above 110 °C. Compared with the homogeneous catalyst, the branching numbers of the polyethylenes obtained by the supported catalysts S-C1-a/b is significantly lower. The polyethylenes obtained by supported catalyst S-C1-a/b at 30-50 °C are free-flowing particles, which is obviously better than the rubber-like cluster polymer obtained from homogeneous catalyst.

Rational design of a topological polymeric solid electrolyte for high-performance all-solid-state alkali metal batteries.

Poly(ethylene oxide)-based solid-state electrolytes are widely considered promising candidates for the next generation of lithium and sodium metal batteries. However, several challenges, including low oxidation resistance and low cation transference number, hinder poly(ethylene oxide)-based electrolytes for broad applications. To circumvent these issues, here, we propose the design, synthesis and application of a fluoropolymer, i.e., poly(2,2,2-trifluoroethyl methacrylate). This polymer, when introduced into a poly(ethylene oxide)-based solid electrolyte, improves the electrochemical window stability and transference number. Via multiple physicochemical and theoretical characterizations, we identify the presence of tailored supramolecular bonds and peculiar morphological structures as the main factors responsible for the improved electrochemical performances. The polymeric solid electrolyte is also investigated in full lithium and sodium metal lab-scale cells. Interestingly, when tested in a single-layer pouch cell configuration in combination with a Li metal negative electrode and a LiMn0.6Fe0.4PO4-based positive electrode, the polymeric solid-state electrolyte enables 200 cycles at 42 mA·g-1 and 70 °C with a stable discharge capacity of approximately 2.5 mAh when an external pressure of 0.28 MPa is applied.

Cr-Catalyzed Direct ortho-Aminomethylation of Phenols.

We developed a Cr-catalyzed strategy for the regioselective formation of Csp2-Csp3 bonds through the direct and efficient ortho-aminomethylation of N,N-dimethylanilines with phenols. The approach showed excellent site selectivity at the ortho-position of phenols and accommodated broad substrate scope and functional group compatibility for both N,N-dimethylanilines and phenols. Mechanistic studies revealed that the direct ortho-aminomethylation between N,N-dimethylanilines and phenols occurred via an ionic mechanism.

Construction of Mechanically Reinforced Thermoplastic Polyurethane from Carbon Dioxide-Based Poly(ether carbonate) Polyols via Coordination Cross-Linking.

Using carbon dioxide-based poly(propylene ether carbonate) diol (PPCD), isophorone diisocyanate (IPDI), dimethylolbutyric acid (DMBA), ferric chloride (FeCl3), and ethylene glycol (EG) as the main raw materials, a novel thermoplastic polyurethane (TPU) is prepared through coordination of FeCl3 and DMBA to obtain TPU containing coordination enhancement directly. The Fourier transform infrared spectroscopy, 1H NMR, gel permeation chromatography, UV-Vis spectroscopy, tensile testing, dynamic mechanical analysis, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were explored to characterize chemical structures and mechanical properties of as-prepared TPU. With the increasing addition of FeCl3, the tensile strength and modulus of TPU increase. Although the elongation at break decreases, it still maintains a high level. Dynamic mechanical analysis shows that the glass-transition temperature moves to a high temperature gradually along with the increasing addition of FeCl3. X-ray diffraction results indicate that TPUs reinforced with FeCl3 or not are amorphous polymers. That FeCl3 coordinates with DMBA first is an effective strategy of getting TPU, which is effective and convenient in the industry without the separation of intermediate products. This work confirms that such Lewis acids as FeCl3 can improve and adjust the properties of TPU contenting coordination structures with an in-situ reaction in a low addition amount, which expands their applications in industry and engineering areas.

Preparation and crystalline transformation of functionalized poly(1-butene) containing PFPU and mPEG side chain.

A series of 1-butene/pentafluorophenylundec-1-ene ester random copolymers were synthesized under the Ziegler-Natta catalyst system. The content of the pentafluorophenyl (PFP) group in the copolymer can reach up to 0.59 mol%. The DSC test found that the PFP groups attached to the PB main chain retard the crystalline transformation of Form II to Form I. Nucleophilic aromatic substitutions of pentafluorophenyl ester occurred with biocompatible poly(ethylene glycol) methyl ether (mPEG) introduced into the side chain of PB under very mild conditions. The results show that not only is the crystallization rate of mPEG functionalized PB increased, but also T m, T c, χ c and the crystalline phase transition rate of Form II to Form I are also enhanced. Among them, mPEG with a M n of 500 has the best promoting effect. On the other hand, the hydrophilicity of mPEG-functionalized PB is improved, and it is proportional to the chain length of mPEG. However, the experimental results show that the regularity of the PB structure is the determinant of the rate of crystallization and phase transition.

Organocatalytic Strategy for the Fixation of CO2 via Carboxylation of Terminal Alkynes.

An organocatalytic strategy for the direct carboxylation of terminal alkynes with CO2 has been developed. The combined use of a bifunctional organocatalyst and Cs2CO3 resulted in a robust catalytic system for the preparation of a range of propiolic acid derivatives in high yields with broad substrate scope using CO2 at atmospheric pressure under mild temperatures (60 °C). This work has demonstrated that this organocatalytic method offers a competitive alternative to metal catalysis for the carboxylation of terminal alkynes and CO2. In addition, this protocol was suitable for the three-component carboxylation of terminal alkynes, alkyl halides, and CO2.

Preparation of Boron Nitride Nanoplatelets via Amino Acid Assisted Ball Milling: Towards Thermal Conductivity Application.

Hexagonal boron nitride nanoplatelets (BNNPs) have attracted widespread attention due to their unique physical properties and their peeling from the base material. Mechanical exfoliation is a simple, scalable approach to produce single-layer or few-layer BNNPs. In this work, two amino acid grafted boron nitride nanoplatelets, Lys@BNNP and Glu@BNNP, were successfully prepared via ball milling of h-BN with L-Lysine and L-Glutamic acid, respectively. It was found that the dispersion state of Lys@BNNP and Glu@BNNP in water had been effectively stabilized due to the introduction of amino acid moieties which contained a hydrophilic carboxyl group. PVA hydrogel composites with Lys@BNNP and Glu@BNNP as functional fillers were constructed and extensively studied. With 11.3 wt% Lys@BNNP incorporated, the thermal conductivity of Lys@BNNP/PVA hydrogel composite was up to 0.91 W m-1K-1, increased by 78%, comparing to the neat PVA hydrogel. Meanwhile, the mechanical and self-healing properties of the composites were simultaneously largely enhanced.

A gadolinium(III)-porphyrin based coordination polymer for colorimetric and fluorometric dual mode determination of ferric ions.

A coordination polymer (CP) based nanoprobe is described for colorimetric and fluorometric (dual mode) determination of ferric ion. The method is making use of a nanosized Gd(III)-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin coordination polymer that was prepared by a single-step hydrothermal procedure. The nanoprobe is monodisperse and has uniform size and good water solubility. It also exhibits strong fluorescence and magnetic resonance response. On exposure to Fe(III), the color of the solution changes from red to brown as the concentration of Fe(III) exceed 5 µM. Similarly, the red fluorescence of the probe (with excitation/emission peaks at 420/675 nm) decreases as concentrations of Fe(III) increase from 0.5 to 100 µM. The limit of detection is 98 nM in the fluorometric mode. The assay was applied to the determination of Fe(III) in fetal bovine serum samples. Graphical abstract Schematic presentation of the synthesis and application of lanthanide-porphyrin based coordination polymer for ferric ion detection in colorimetric and fluorometric dual modes.

The influence of polymer architectures on the dewetting behavior of thin polymer films: from linear chains to ring chains.

The dewetting behavior of ring polystyrene (RPS) film and linear polystyrene (LPS) film on silanized Si substrates with different grafting densities and PDMS substrate was investigated. Results showed that polymer architectures greatly influenced the dewetting behavior of the thin polymer film. On the silanized Si substrate with 69% grafting density, RPS chains exhibited stronger adsorption compared with LPS chains, and as a result the wetting layer formed more easily. For LPS films, with a decreased annealing temperature, the stability of the polymer film changed from non-slip dewetting via apparent slip dewetting to apparently stable. However, for RPS films, the polymer film stability switched from apparent slip dewetting to apparently stable. On the silanized Si substrate with 94% grafting density, the chain adsorption became weaker and the dewetting processes were faster than that on the substrate with 69% grafting density at the same experimental temperature for both the LPS and RPS films. Moreover, on the PDMS substrate, LPS films always showed non-slip dewetting, while the dewetting kinetics of RPS films switched from non-slip dewetting to slip dewetting behaviour. Forming the wetting layer strongly influenced the stability and dewetting behavior of the thin polymer films.

Luminescent Lanthanide-Based Organic/Inorganic Hybrid Materials for Discrimination of Glutathione in Solution and within Hydrogels.

Glutathione (GSH) as a biothiol is an essential peptide related to various diseases. Although multiple strategies for biothiols detection have been developed, there is increasing demand for sensors that can differentiate GSH from cysteine (Cys) and homocysteine (Hcy), owing to the similar structures and thiol groups in these amino acids. Herein, we report a novel Eu3+/LAPONITE (Lap)-based organic/inorganic hybrid material for selective detection of GSH via an "off-on" process. The fluorescence of Eu(DPA)3@Lap-Tris can be quenched by Cu2+ through photoinduced electron transfer (PET). The addition of GSH into the Eu(DPA)3@Lap-Tris/Cu2+ system induces the removal of Cu2+ from Eu(DPA)3@Lap-Tris and blocks PET, resulting in the recovery of fluorescence. This proposed assay demonstrates higher selectivity toward GSH than Cys and Hcy, and showed a detection limit of 162 nM within a linear range of 0.5-30 µM. Unlike other GSH selective sensors, this platform could be formed into a hydrogel while its sensitivity was maintained. The sensitive response to GSH in serum samples makes this platform an efficient tool for biological applications because of its ease of preparation, high selectivity, good biocompatibility, and low toxicity.