最新刊期
- 摘要：The self-consistent field theory (SCFT) is employed to study the self-assembly behavior of AB diblock copolymers confined in alternately adsorbed nanopores. Focusing on the emergence and stability of the disk (Dk) phases, a series of phase diagrams are constructed with respect to the alternating adsorption period (w), size of the cylindrical pore (D), and the volume fraction of the A block (f). The results indicate a significant enhanced stability of Dk structure by the alternately adsorbing surface fields. The Dk structure is especially favored, when the alternating adsorption period is around 5.0Rg. With fixed w = 5.0Rg, the appearance of the Dk structure is tuned by D and f, it forms biconcave shape with negative curvatures within a certain varying ranges of D and f, otherwise it transforms into ellipsoidal or toroid shapes. Additionally, a number of novel cylinders and regularly arranged spheres emerged in the nanopores with specific surface fields. The results deepen the understanding of self-assembly behavior of block copolymers under cylindrical confinements, and provide theoretical guidance for the experimental preparation of such complex structures.关键词：Block copolymers;Self-assembly;Cylindrical confinement;Surface field induction;Self-consistent field theory (SCFT)
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发布时间：2024-05-08 - 摘要：The frictional behaviors of implant soft materials in vivo are important to medical effect. In this study, hydroxyethyl acrylate sodium/acryloyldimethyl taurate copolymer (EMT-10) aqueous dispersions are adopted, acting as lubricants in hydrophobic polydimethylsiloxane elastomer (PDMS) Gemini interfaces or hydrophilic polyamide hydrogel (PAM) Gemini interfaces, respectively. The associations exist in EMT-10 aqueous dispersions via hydrogen bonding, electrostatic and hydrophobic interactions, similar to bio-lubricants. The EMT-10 aqueous dispersions, surface characteristics of Gemini interfaces and the axial force (Na) during frictional experiments in Stribeck curves are studied. Under low and high concentrations of EMT-10 lubricant, the PDMS Gemini interfaces exhibit opposing sensitivity to Na, different from the PAM Gemini interfaces, which always showing lower CoF at higher Na. This phenomenon results from the various degree of perfection for lubrication film between the Gemini interfaces. To further distinguish the lubrication film formation, and correlate frictional surface characteristic and rheological behaviors of lubricant, a new parameter, relative thickness (φ), is established. When φ<1, the lubrication film is discrete, and the boundary lubrication regime plays dominant role during the frictional test. When φ>1, the entire lubrication film forms and the whole system enters hydrodynamic lubrication regime. For PDMS Gemini interfaces, the lubrication film is composed of the confined and adsorbed EMT-10 polymer chains owing to the strong attraction between the hydrophobic surface and the C－C backbone. As a result, the lubrication film is greatly affected by the concentration of the lubricant thus φ increases. The PDMS frictional system gradually converts from the boundary into hydrodynamic lubrication regime. For PAM Gemini interfaces, the film is made of the hydrogel surface mesh and the confined EMT-10 chains, so φ is always larger than 1, exhibiting the characteristic of hydrodynamic lubrication regime. The study tends to probe the frictional behavior of the complex fluids in the soft Gemini interfaces and unveils the mechanism behind the phenomenon.关键词：Lubrication;Gemini interfaces;Polydimethylsiloxane elastomer;Hydrogel
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发布时间：2024-05-08 - 摘要：Biomimetic construction of extracellular microenvironment with dynamic viscoelastic behavior is an important strategy for the design of extracellular matrix (ECM) in tissue engineering. In this study, a poly(vinyl alcohol) (PVA)/cellulose nanofiber (CNF) composite hydrogel with anisotropic structure was constructed through the cooperative strategy of directional freezing (DF) and confined drying and re-swelling (CDR). The prepared composite hydrogel showed the oriented fiber arrangement structure parallel to the directional freezing direction. Rheological experiments showed that PVA/CNF composite hydrogel had anisotropic dynamic modulus (G'∥ = (76.77±1.61) kPa and G'⊥ = (42.93±1.34) kPa; G''∥ = (5.44±0.26) kPa and G''⊥ = (3.71±0.13) kPa). The energy storage modulus (G') and loss modulus (G'') improved with the increase of PVA content in the low frequency and low strain regions, and showed a tendency of increasing and then decreasing with the increase of CNF content. The results of stress relaxation experiments indicated that the composite hydrogel had viscoelastic properties. Therefore, the viscoelastic properties and rules of the composite hydrogel with anisotropic structures summarized in this study have potential applications in guiding the design of tissue-engineered biomimetic ECM and its effect on cell biological behavior.关键词：Anisotropy;Composite hydrogel;Extracellular matrix;Rheological behavior;Stress relaxation
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发布时间：2024-05-07 - 摘要：Elastomer materials with long-lasting and stable room-temperature phosphorescence have great potential in the fields of flexible electronics and photonics. However, developing such materials remains a daunting challenge. Systems of small molecule doped polymers are limited by the tensile properties of the polymer matrix. Currently commonly used polymethylmethacrylate (PMMA) and poly(vinyl alcohol) (PVA) have poor tensile properties. However, the increased flexibility cannot provide rigid external conditions for phosphorescence emission. This trade-off parameter adjustment has always hindered its development. Here, we report a highly stretchable and mechanically strong sustainable luminescent room-temperature phosphorescent covalent organic framework elastomer (SPU-D230-UPy COF) material. The material is composed of an alkyl chain soft segment and a limited covalent organic framework containing multiple hydrogen bonding hard segments. This structural design of separated soft and hard segments provides the structural basis for high mechanical properties, high toughness, and phosphorescent emission. The soft segment structure can ensure its high stretchability, and the hard segment structure can provide high mechanical strength while also providing a rigid environment for phosphorescence emission. These prepared elastomers exhibit high mechanical properties and high elasticity, and exhibit bright and sustained luminescence after removal of 365 nm excitation (luminescence time lasts for 3.0 s). Mechanical studies show that the obtained material exhibits a strength of ∼33.5 MPa and excellent toughness of ∼188.26 MJ/m3, with a Young's modulus of ∼76.6 MPa. The material can easily lift heavy objects without breaking. Impressively, these elastomers maintain strong optical properties even under repeated mechanical deformation, an unprecedented property. These outstanding properties make these long-lasting luminescent elastomers ideal for potential applications in wearables, flexible displays, and anti-counterfeiting devices. This separate structural design of soft and hard segments effectively breaks the trade-off between structural flexibility and phosphorescence emission. It can not only improve the mechanical properties, flexibility and stretchability of the material, but also effectively maintain the phosphorescence emission, which will provide a new path for the development of stretchable elastomer phosphorescent emissive materials.关键词：Elastomer;Covalent organic framework;ultralong room temperature phosphorescence;multiple hydrogen bonds
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发布时间：2024-04-29 -
Preparation and Research of Polyurethane Based Anti-icing Coating Based on Different Young's Modulus
摘要：Using 4,4'-diphenylmethane diisocyanate (MDI) and polytetrahydrofuran ether diol (PTMEG) as precursors, a one-component wet-cured polyurethane elastomer (PUE) coating with tunable Young's modulus (0.72-5.95 MPa) was synthesized by manipulating the R value. The effect of Young's modulus of coating on ice adhesion strength was studied by comparing polyether diols with different molecular weights. The results show that higher molecular weight series of polyether diols exhibit lower ice adhesion strength (average 57.71 kPa). As the Young's modulus of the coating increases, the corresponding ice adhesion strength initially rises and then declines. The analysis reveals that the surface of the coating with low Young's modulus (for example, PTMEG-1000 as the soft segment, 1.05-2.96 MPa) is easily deformed during water icing expansion, forming uneven structures and providing more adhesion points for the ice structure to adhere, which makes the ice adhesion strength closely related to the surface energy, resulting in the possibility of increasing the ice adhesion strength. However, the decrease interval of ice adhesion strength in coatings with higher Young's modulus (for example, PTMEG-1000 as the soft segment, 2.96-5.95 MPa) is not consistent with the positive correlation between Young's modulus and ice adhesion strength. This is due to the effect of low temperature resilience, the elastic mismatch between the ice and the coating induces micro-cracks and cavitation of the ice-coating interface, resulting in the possibility of reducing the ice adhesion strength. Therefore, understanding how coating's Young's modulus affects ice adhesion can be effectively utilized to reduce such adhesive properties.关键词：Polyurethane elastomer;Young's modulus;Ice adhesion strength;Mechanical property- 83
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发布时间：2024-04-28 - 摘要：This study focuses on the development of a sustainable and highly sensitive Antheraea pernyi silk paper-based electrochemical sensor, utilizing the excellent solvent resistance of silk paper as the substrate and incorporating molybdenum disulfide (MoS2) functional units. The electrochemical sensing principle of this sensor is based on a transpiration-driven electricity generation mechanism. Different solvents interact distinctly with the sensor, resulting in transpiration-driven electrical signals with varying characteristics. Although these electrical signals display complex band-shaped patterns lacking sharp peaks or specific mutation points, they exhibit highly reproducible trends for specific solvent systems. Consequently, this study further employs a feedforward neural network to construct a solvent identification model based on the oak silk fibroin ultrafine paper electrochemical sensor. This model processes and analyzes these complex yet highly repetitive electrical signals. The AI-driven A. pernyi silk paper-based electrochemical sensor not only accurately identifies solvents with highly similar chemical structures and properties, such as methanol, ethanol, isopropanol, and deionized water, but also recognizes chemically similar mixed solvent systems, like varying proportions of ethanol-water mixtures. In 100 identification tests, the accuracy was 100%. The development of this AI-driven A. pernyi silk paper-based electrochemical sensor offers a convenient, cost-effective method for rapid and accurate solvent detection, holding significant implications in fields such as alcohol testing, environmental monitoring, and chemical analysis.关键词：Silk paper;Eutectic solvent;Depolymerization;Electrochemical sensor;Deep learning
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发布时间：2024-04-25 - 摘要：The properties and applications of crystalline polymer materials largely depend on their crystallinity. Rapid preparation of highly crystalline or single crystal polymer materials is not only beneficial for studying their structure-property relationship, but can also expand their practical applications. However, efficiently and accurately assembling organic molecules into polymer single crystals through polymerization is a challenging task. To address this issue, our group has developed a supercritically-solvothermal method for achieving ultra-fast preparation of polymer single crystals. This method uses supercritical carbon dioxide as the reaction medium, which greatly improves the growth rate of polymer crystals due to its high diffusion rate and low viscosity. This feature article reviews the commonly used synthesis methods for covalent organic frameworks (COFs), as well as the challenges faced in single crystal preparation. Then, the basic properties and applications of supercritical fluids, the advantages of supercritically-solvothermal method, and the structural characterization of the prepared COF single crystals are systematically discussed. Finally, the challenges and development directions faced in the synthesis of polymer single crystals by supercritically-solvothermal method are prospected.关键词：Supercritically-solvothermal method;Polymer;Single crystal;Covalent organic frameworks;Fast synthesis
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发布时间：2024-04-24 - 摘要：Combining features of liquid crystal polyester (LCP) and benzocyclobutene (BCB), two BCB-containing compounds, 2-(dicyclo[4.2.0]oct-1,3,5-triene-3-yl)-5-hydroxy-1H-isoindole-1,3(2H)-diketone (BCB-HP) and 2,3-dihydro-1,3-dioxo-2-(dicyclo[4.2.0]oct-1,3,5-triene-3-yl)-1H-isoindole-5-carboxylic acid (BCB-CP), were designed and prepared as terminal capping compounds for LCP synthesis. Liquid crystal polyesterimides (LCPEIs) were synthesized by solution condensation copolymerization of the phenolic BCB-HP, the carboxylic BCB-CP, 4-hydroxybenzoic acid (4-HBA), and 6-hydroxy-2-naphthoic acid (HNA), along with N-(3-carboxyphenyl)-4-hydroxyphthalimide (3-CHP), in the presence of esterification reagents and conditions, diphenyl chlorophosphate (DPCP), LiCl and pyridine at room to reflux temperature, and subsequent methanol precipitation and drying as fine powder. Films of LCPEI-22/44-BCB (with 22 mol%/44 mol% 3-CHP) were generated by hot-pressing and curing procedures, and the curing temperature is around 270 ℃, which is favorably lower than those of 3-ethynylaniline (3-EA, 310 ℃) and 4-phenylethynylphthalic anhydride (PEPA, 370 ℃), two alkyne-type thermal reactive terminal groups used in literature. These BCB-type LCPEIs have good thermal stabilities (Td5% = 416.7-454.8 ℃) in thermo-gravimetric analysis (TGA) under nitrogen gas. Compared with the commercially available Vectra A950 LCP and non-BCB-containing LCPEI-22/44, LCPEI-22/44-BCB have better solubility (4/1 v/v chloroform-pentafluorophenol), lower melting temperature (Tm, 200 ℃), higher glass transition temperature (Tg, 149-167 ℃), and lower isotropic temperature (Ti, 350 ℃), indicating processing convenience and application potential. Compared to LCPEI-22, film of LCPEI-22-BCB has a favorably lower linear thermal expansion coefficient (CTE, 41.13 versus 73.29×10-6 K-1), a higher storage modulus (E', 3.48 versus 0.53 GPa), higher elastic modulus (Er, 10.83 versus 9.40 GPa), and higher hardness (H, 0.66 versus 0.58 GPa). Film of LCPEI-22-BCB also has better hydrophobicity with increased water contact angle (124.7° versus 114.3°). Film of LCPEI-22-BCB exhibits good and comparable low dielectric constant (Dk=3.364) and excellent low dielectric loss (Df=0.0019) at 10 GHz high frequency and room temperature. Merits of the above features would make the BCB-type LCPEIs promising materials for flexible copper clad laminates.关键词：Liquid crystal polyester;Polyesterimide;Benzocyclobutene;Low dielectric constant
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发布时间：2024-04-24 - 摘要：The aramid fiber reinforced polyurethane composites (AF@PU), which exhibit high strength and lightweight characteristics, have attracted widespread concerns for advanced personal protective systems. However, the interface has consistently been the scientific issue that permeates composite research and is frequently overlooked. In this work, polydopamine and γ-aminopropyltriethoxysilane modified SiO2 (m-SiO2) were used to optimize the interfacial properties, and the effects on ballistic performance and ballistic damage mechanism of composites were deeply investigated. Attributing to the strong bonding strength between fibers and polymer resins improved by them at the interface, the interfacial peeling strength of m-SiO2/PDA/AF@PU is increased by 244.1% (4.68 N/cm); the interlaminar shear strength is increased by 30.7% (6.09 MPa); the tensile, flexural and compressive strength of is maximally increased by 5.0%, 91.4% and 69.5%, respectively. Notably, because the introduction of abundant m-SiO2 enhances the interface roughness, m-SiO2/PDA/AF@PU demonstrates the maximal energy absorption value; the ballistic limit velocity is improved from 449.8 m/s of AF@PU to 481.9 m/s of m-SiO2/PDA/AF@PU. This work highlights the optimization of interfacial properties and provides an efficient guideline for the design of next-generation fiber reinforced polymer resin composites.关键词：Composites;Interfacial modification;Polydopamine;Nano silica;Ballistic performance
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发布时间：2024-04-24 - 摘要：A series of large-ring metal coordination catalysts with manganese (Ⅲ) as the axial ligand and alkali metal (Ⅰ) as the core were synthesized in this experiment, and their structures were characterized in detail by MALDI-TOF-MS and elemental analysis. These catalysts can catalyze the polymerization of propylene glycolide (LA) and ε-caprolactone (ε-CL) in the presence of cyclohexane oxide (CHO). We screened and optimized different alkali metal ions to ensure the best polymerization performance. The experimental results show that the introduction of alkali metal centers significantly improves the performance of the catalysts, far exceeding that of mononuclear Schiff base manganese catalysts. The steric hindrance effect of the amine bridge moiety of the catalyst on the reaction activity is also significant. We investigated the stereo-selectivity of the catalysts for monomers and conducted copolymerization studies using different LA isomers, finding that this catalyst is more prone to obtaining polymers with isotactic tendencies. The polymerization mechanism was further analyzed by using MALDI-TOF-MS spectrometer to analyze the end groups of the obtained PLA and assist in the study of the polymerization mechanism. Experimental studies show that the stereo-selectivity of the polymerization is achieved through a chain-end control mechanism.关键词：Heterodinuclear complex;Polylactic;Polycaprolactone;Ring-opening polymerization;Non-homogeneous catalysts
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发布时间：2024-04-24 - 摘要：It is a desirable method to develop high energy density supercapacitors without sacrificing power density to prepare electrode materials with both capacitance and battery characteristics by composite modification of conductive conjugated polymers. In this study, the intermolecular force is strengthened by electron-withdrawing groups to improve the charge transfer performance of materials, improve the cyclic stability of electrode materials and make them have higher energy density and power density. We use liquid-phase treatment to treat CC and in situ oxidation polymerization to polymerize three D-A type conductive conjugated polymers on the surface of CC with 2,3-dichloro-5,6-dicyano-p-benzoquinone as the acceptor and 3,3-dimethylbenzidine, 3,3-dimethoxybenzidine and 3,3-dihydroxybenzidine as the donors. We studied the capacitance characteristics of three flexible composite electrodes. The P2/CC electrode material with a donor end of 3,3-dimethoxybenzidine exhibits fast electrochemical kinetics characteristics in the range of less than 70 mV·s-1, its discharge specific capacitance reaches 686.27 F·g-1 at a current density of 0.5 A·g-1, and the retention rate of the specific capacitance after 5000 charge discharge cycles is 99.70%. The composite electrode also achieved an energy density of 50.66 Wh·kg-1 at an ultra-high power density of 497.46 W·kg-1. The organic-inorganic synergistic effect between conductive conjugated polymers and CC helps to improve the conductivity and stability of electrodes, and the pseudocapacitive charge storage behavior of conductive conjugated polymers enhances the discharge specific capacity. The preparation of flexible composite electrodes provides a favorable reference for the low-cost development of new electrode materials with high energy density and power density to further improve the performance of supercapacitors.关键词：D-A type conductive polymer;Carbon cloth;Flexible electrodes;High energy density;High power density
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发布时间：2024-04-24 - 摘要：Sodium lignosulfonate (LSS) with good photothermal property and gold nanoparticles (Au NPs) with excellent localized surface plasmon resonance (LSS) were used as raw materials to fabricate LSS/PVA@Au composite films with synergistic photothermal effect through in situ blending strategy. During the preparation process, the functional groups on the LSS structure play an important role in dispersing, stabilizing, chelating and reducing Au3+. The existence of Au NPs makes the surface of the LSS/PVA@Au composite film rougher, with an average roughness of 30.3 nm, which also endows its stronger and wider absorption in the ultraviolet to near infrared region. The increase of LSS content is beneficial to the enhancement of photothermal property of the LSS/PVA composite material. The maximum temperature of the LSS50/PVA50 composite film can reach (120.6±3.1) ℃ with thermal conversion efficiency of 27.61% under standard 5 sun irradiation. Benefiting from the synergistic photothermal effect of Au NPs, the highest temperature of (190.1±3.5) ℃ can be attained for LSS50/PVA50@Au1 composite film with thermal conversion efficiency of 42.47%. A thermoelectric generator are powered by LSS50/PVA50 and LSS50/PVA50@Au1 composite films successfully, which can convert the heat absorbed into electric energy. The maximum voltage generated by LSS50/PVA50@Au1 is (280.8±4.6) mV and the corresponding current is (48.9±1.9) mA under standard 5 sun irradiation. Due to the good photo-responsiveness to near infrared light (NIR), the LSS50/PVA50@Au1 composite film also show satisfactory photothermal antibacterial performance. After 10 min irradiation of 1.47 W NIR, the antibacterial rates of E.coil and S.aureus can reach 99.5% and 99.2%, respectively. In summary, through a simple, green, and efficient composite blending strategy, abundant solar energy resources can be utilized effectively through the synergistic photothermal effect of LSS and Au NPs. Considering the satisfactory effective antibacterial activity of the LSS50/PVA50@Au1 composite, this work may provide perspectives on the design of green photothermal antibacterial materials via pulp and paper industry waste lignin sulfonate as well as contributes to the enrichment of linin structure and chemistry.关键词：Sodium lignin sulfonate;gold nanoparticles;Photothermal effect;Photothermal-antibacterial
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发布时间：2024-04-24 - 摘要：The ring-opening copolymerization of epoxides and cyclic anhydrides constitutes a straightforward route for synthesizing polyesters. The resultant copolymers are mainly obtained with alternating structures, which might limit their application situations due to their low toughness caused by the high density of ester group. It has been demonstrated that the incorporation of ether segments into the mainchain of polyesters is an efficient strategy to tune the thermal and mechanical properties of polyesters, which is greatly limited by the lack of efficient catalyst. In response to these issues, this study proposed to achieve the random copolymerization of cyclohexene oxide (CHO) and phthalic anhydride (PA) to prepare poly(ether-ester)s via the hetero-bimetallic synergistic catalysis strategy. A series of heterodinuclear Al-K complex has been designed for catalyzing the copolymerization of CHO and PA. The structures of the resultant copolymers are confirmed as poly(ether-ester)s using nuclear magnetic resonance spectroscopy and electrospray ionization mass spectrometry. The exploration of the polymerization process further revealed the randomly structure of obtained poly(ether-ester)s, that is, ester and ether segments were randomly distributed in the polymer mainchain. Systemic studies on the effects of ligand structure, metal ions, reaction temperature and catalyst concentration on the copolymerization were explored, indicating that it is the synergistic cooperation between two metal centers that results in the formation of random copolymers. In addition, thermal property characterization of resultant copolymers indicates that the incorporation of polyether segments into polyester could effectively tune their glass transition temperatures, thus enriching the application of polyester materials.关键词：Poly(ester-ether)s;Heterodinuclear metal complex;Ring-opening copolymerization;Random copolymer
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发布时间：2024-04-24 - 摘要：This study presents a simple method to obtain LCE with high degree of substitution (DS>2.5) by directly utilizing microcrystalline cellulose (MCC), trifluoracetic anhydride (TFAA), and long chain lauric acid (LA). The impact of ball milling speed, grinding time, and feeding ratio on substitution, melting behavior, and thermal stability is thoroughly investigated. The results show that with increasing ball milling speed and time, LCE substitution increased and the melting temperature decreased. When the DS is larger than 2.81, LCE can be completely melted. Optimal conditions involve a feed ratio of 1:6:3, and ball milling at 400 r/min for 4 h yields cellulose laurel ester with a flow temperature (Tf) of 115 ℃ and a decomposition temperature of 324 ℃. In addition, the introduction of PVA into the system is explored to mitigate excessive TFAA and the side product trifluoroacetic acid. The results show that PVA not only fixed trifluoroacetic acid successfully but also had little effect on the melting and processing properties of the product. This strategy has significant advantages over conventional homogeneous methods, such as streamlining the preparation process, reducing monomer quantities, shortening reaction time, and promoting environmental friendliness. Its potential application in large-scale industrial production of thermoplastic cellulose derivatives is promising.关键词：Cellulose;Cellulose laurate ester;Mechanochemistry;Heterogeneous reaction
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发布时间：2024-04-23 - 摘要：Incorporating ultra-low loading of nanoparticles into polymer matrices can simultaneously improve the dielectric constant and breakdown strength, thereby significantly increasing the capacitance energy storage density of polymer nanocomposites and miniaturing electronics and devices. However, there are still a series of tough issues to be dealt with, such as the use of organic solvents in the current solution blending, which face enormous challenges in scalable preparation and application of the polymer nanocomposites. Here, a dual in situ synthesis strategy is proposed, namely the polymerization of polyethylene terephthalate (PET) synchronizes with the growth of calcium borate nanoparticles. In particular, 0.2 wt% calcium borate nanoparticles are uniformly dispersed in the PET matrix without any solvent, and rich compatibility of the interfaces occurs. The dielectric constant reaches 4.91 and the maximum energy storage density is up to 10.69 J/cm3, which is 1.94 times that of neat PET. The unique dual in situ synthesis strategy tends to be extended to the scalable fabrication of polyester nanocomposites filled with a variety of borates, which paves a way for exploring electrical energy storage and other applications of polyester nanocomposites.关键词：Dual in situ;Ultra-low filled;Dielectric properties;Energy storage density
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发布时间：2024-04-23 - 摘要：Poly(lactic acid) (PLA) is one of the most important biodegradable polymers, which has attracted much attention due to its renewable raw materials and excellent biodegradation properties. The quest to develop sustainable and high-performance catalytic technologies as alternatives to the tin catalysts, which are prevalent currently, is a hot topic in this field. Cyclic PLA, contrasting with the extensively produced linear PLA, has garnered significant attention due to its superior crystallinity, thermal stability, and low intrinsic viscosity, and it has been reported that the mixture of cyclic poly(lactic acid) and linear poly(lactic acid) has better hydrolysis resistance and thermal stability. This study reports the design and synthesis of a binuclear guanidine zinc complex, exhibiting exceptional activity (TOF = 7.50×103-3.45×104 h-1) in catalyzing lactide ring-opening polymerization for the efficient production of cyclic poly(lactic acid) under simulated industrial conditions. Gel permeation chromatography (GPC) analysis revealed a narrow, unimodal distribution (1.25-1.49) of the obtained products, with a molecular weight range of 6.2-34.3 kg/mol. Matrix-assisted Laser Desorption Ionization Time-of-flight Mass Spectrometry (MALDI-TOF-MS) characterization of low molecular weight products confirmed the predominant presence of cyclic PLA, allowing for the proposal of a plausible ring formation mechanism. Moreover, the experiment demonstrated the binuclear guanidine zinc complex's effective catalytic action on a diverse range of lactone monomers, offering a novel avenue for the development of broad-spectrum catalytic systems within the realm of metal catalysis.关键词：Metal guanidine complex;Lactide;Cyclic poly(lactic acid);Binuclear zinc complex
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发布时间：2024-04-23 - 摘要：To investigate the effective procedure for controlled polymer structure and thermal properties through radical polymerization, amylose derivatives were used as chiral additives to induce the radical polymerization of methyl methacrylate (MMA). The effect of amylose derivatives on the structure and thermal properties of polymethylmethacrylate (PMMA) was subsequently explored. Four kinds of amylose derivatives were synthesized through carbamoylation, including amylose tri(4-chlorophenyl carbamate) (ACPC), amylose tri(phenylcarbamate) (ATPC), amylose tri(4-methylphenylcarbamate) (AMPC) and amylose tri(S-(-)-α-methylbenzyl carbamate) (ASMBC). The structures and degree of substitution of the amylose derivatives were characterized by magnetic resonance spectroscopy (1H-NMR) and CD spectra, demonstrating complete substitution and regular chiral helical structure of the obtained derivatives. The thermal stability of PMMA was assessed using DSC and thermogravimetric analysis (TGA), revealing a significant enhancement in the thermal stability of PMMA induced by amylose derivatives. Furthermore, the substituents properties of the derivatives and the polarity of the polymerization solvent significantly influenced the radical polymerization behavior of MMA. Both bulk polymerization and solution polymerization were effective in improving the thermal properties of PMMA, with the solution polymerization system utilizing non-polar octane as the solvent achieving the most significant improvement. Among the amylose derivatives, the para-methyl-substituted amylose derivatives (AMPC) demonstrated the most effective induction effect, which could increase the glass transition temperature (Tg) and the onset decomposition temperature (T0) of PMMA by 26 and 71 ℃, respectively. The induction mechanism of amylose derivatives was investigated using gel permeation chromatography (GPC), dynamic laser light scattering (DLS) and X-ray diffraction (XRD). The results indicated that MMA monomers could be arranged in order along the chiral helical cavity of the derivatives. This ordered arrangement can not only improve the structure order of polymer molecular chains, but also have a positive effect on its aggregation behavior, thereby achieving effective control of the thermal properties of PMMA. It suggests that the radical polymerization behavior and thermal properties of MMA can be effectively regulated by selecting appropriate helical polymers, offering a novel idea for exploring the controlled radical polymerization method of methacrylate monomers.关键词：Amylose derivatives;Polymethyl methacrylate;Thermal stability;Free radical polymerization
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发布时间：2024-04-19 - 摘要：Fluoropolymers possess many outstanding physical and chemical properties, allowing applications in aerospace, defense, chemicals, new energy, biomedicine, etc. Reversible deactivation radical polymerization (RDRP) is among the important methods for realizing precise synthesis of polymers. However, compared with the (methyl)acrylate and styrene derivatives, RDRPs of fluorinated monomers are very limited. Recently, a growing number of research reports demonstrated that the precise regulation of polymer structures contributes to improving properties of polymers, promoting the development of high-end materials. Herein, this review focuses on RDRPs of fluorinated monomers, introduces the research advancements of the controlled synthesis of side-chain and main-chain fluorinated polymers, and summarizes the RDRP reports of fluorinated acrylates, fluorinated styrene, chlorotrifluoroethylene, tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, and perfluoroalkyl vinyl ethers. Given the urgent need for customized synthesis of fluorinated polymers in many frontier fields, the development of controlled synthesis methods for fluorinated polymers will not only contribute to regulating the structural scope of fluorinated polymers but also facilitate the production of high-performance fluorinated polymer materials. This review serves as a valuable resource for researchers working in the field of fluorinated polymers, providing an overview of the current state of the art and briefly illustrating the prospects and challenges for the RDRP of fluorinated monomers.关键词：fluoropolymers;fluoroalkenes;reversible deactivation radical polymerization (RDRP);Living polymerization
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发布时间：2024-04-18 - 摘要：Based on the synergistic non-covalent interaction of tadpole-like single-chain particles with multiple sites on the wafer surface, a PEG brush grafting strategy has been developed that combines ease of handling and excellent "biofouling" properties. Specifically, the block copolymer poly(ethylene glycol)-b-poly(4-vinylpyridine) (PEG-b-P4VP) was synthesized by atom transfer radical polymerization (ATRP). The P4VP block was then intra-chain cross-linked using the "electrostatic-mediated" strategy, and the P4VP "head" was completely quaternized by further addition of excess ethyl iodide, yielding tadpole-like single-chain particles with completely quaternized "heads" (TSCP-Q). By simple solution immersion grafting method, the completely cross-linked and collapsed "head" significantly reduces its adsorption area on the silicon wafer through multi-site non-covalent synergistic interaction, while the extended PEG "tail" ensures grafting uniformity of TSCP-Q brushes on the surface through volume repulsion effect. As a result, the obtained TSCP-Q brushes achieve stable and uniform grafting on the silicon wafer, with PEG "tail" overlying the P4VP "head" anchoring layer and effectively masking the charge of the anchoring layer. The TSCP-Q brushes were shown to have excellent anti-bovine serum albumin (BSA) adsorption (4.8 ng/cm2) and could effectively inhibit the colonization of Staphylococcus aureus (S. aureus) (killing efficacy up to 81%).关键词：Tadpole-like single-chain particle;Polymer brush;Poly(ethylene glycol);Anti-protein adsorption;Antibacterial
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发布时间：2024-04-18 - 摘要：Soft matter science is an important branch in the fields of physics, chemistry, and material science. However, the complexity of soft matter systems, especially their multi-scale structures and rich dynamic behaviors, poses significant challenges to researchers. To address these challenges, simulation methods based on field theory demonstrate unique advantages in simulation techniques. By introducing continuous field variables, they provide a more efficient and macroscopic perspective for describing and handling complex interactions in soft matter systems. This article first introduces the basic principles of polymer field theory and elaborates on their applications in soft matter physics, such as the structure prediction of protein HP models, the static topological entanglement problems of polymer chains, chemical reaction/light induced microphase separation, etc. It then explores the application of modern computational technologies like deep learning in soft matter research, and finally looks forward to the future research trends and developments in the field of soft matter, pointing out that field theory remains a powerful tool for soft matter study.关键词：Soft matter;Simulation methods based on field theory;Self-consistent field theory;Deep learning
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发布时间：2024-04-18
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