最新刊期
卷 36 ， 期 10 ， 2023
- 摘要：Polyolefin is one of the most-consumed and most widely used synthetic resins. The incorporation of even a small amount of functional groups would endow polyolefin with polarity, reactivity, adhesiveness, antioxidant and fluorescence properties while maintaining their novel intrinsic properties, thus obtaining functional polyolefin with imperative applications. Post modification is nowadays the essential route to produce functional polyolefin. Suffering from poor control on the reaction process and inevitable side reactions, traditional free radical grafting (FRG) method can only produce ill-defined functional polyolefin with relatively low grafting ratios. Through utilization of new initiators, control on the grafting reactions can be enhanced, resulting in polyolefin with high grating ratios. Owing to its excellent control and diverse functional groups available, C—H activation has now emerged as a powerful tool to synthesize well-defined functional polyolefin. After a brief introduction on new developments on FRG, this review contributes a detailed survey on the advances on synthesis of functional polyolefin via efficient C—H activation.关键词：Polyolefin Post-modification;Radical;Grafting;Carbon Hydrogen Bond;Activation;Catalysis
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发布时间：2023-09-19 - 摘要：Paclitaxel is an effective natural compound with anticancer properties. However, its hydrophobicity leads to the limitation of clinical application. In order to solve this problem, amphiphilic polymers are generally used as their drug delivery carriers to achieve effective drug encapsulation and efficient drug delivery. For instance, water-soluble polyvinylpyrrolidone, is combined with hydrophobic segments to form amphiphilic copolymers, which is used in paclitaxel drug delivery system, owing to its excellent hydrophilicity and biocompatibility. In this paper, the controllable preparation methods of polyvinylpyrrolidone and its block copolymers are reviewed, and their applications in paclitaxel drug delivery systems are summarized. How to design and fabricate drug delivery carrier based on paclitaxel with comprehensive performance is prospected.关键词：Polyvinylpyrrolidone;Paclitaxel;Drug release;Controlled radical polymerization
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发布时间：2023-09-19 - 摘要：With the continuous advancement of modern technology and the wide application of combustible materials, fire safety has become a global challenge. In order to fundamentally reduce the negative impact of conflagration, the research and application of fire safety sensors have gradually attracted people’s attention. Fire warning sensors and self-flame-retardant sensors are the two cores of fire safety sensor. The former mainly uses carbon nanotubes, graphene oxide and transition metal carbon/nitride as the most mainstream materials, focusing on its response speed and alarm duration. The latter focuses on the research of non-halogen materials like red phosphorus, and the self-extinguishing characteristics of sensors are mainly studied. Nevertheless, it hasn’t been studied enough with few articles published. This review comprehensively discusses the concept, preparation, characterization methods and research significance of fire safety sensors based on polymer materials. Meanwhile, performances of different substrates in recent years are summarized and compared to explore the application potential of different sensors, so as to better understand the properties and working mechanism of sensors, providing guidance to solve the problems faced by fire safety sensors.关键词：Polymer materials;Fire-warning sensor;Self-flame-retardant sensor;Fire performance
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发布时间：2023-09-19 - 摘要：Ultrahigh molecular weight polyethylene (UHMWPE) is widely used in national defense, military, aerospace, marine engineering and sporting goods and other fields with its excellent physical and chemical properties such as wear resistance, impact resistance and corrosion resistance. More recently, catalysts that regulate UHMWPE morphology, molecular weight and distribution, branching degree, etc. have attracted great attentions from scientists. The development of Ziegler-Natta catalysts, metallocene catalysts, FI catalysts and posttransition metal catalysts for UHMWPE polymerization are reviewed.关键词：Ultrahigh molecular weight polyethylene;Ziegler-Natta catalysts;Phenoxy imine-based catalysts;Post-transition metal complex
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发布时间：2023-09-19 - 摘要：Attributed to the advantages of mechanical flexibility, high sensitivity, excellent repeatability, low power consumption, and high spatial resolution, polymer-based flexible capacitive pressure sensors have attracted widespread attention, which are widely used in wearable electronic devices, electronic skin, and other fields. In this review, we briefly introduce various pressure sensing materials with different sensing mechanisms. Subsequently, we systemically summarize the recent progress of polymer-based flexible capacitive pressure sensing materials, including their sensing mechanisms, advantages and disadvantages as well as optimization strategies. Finally, the current challenges and future development trends of capacitive pressure sensing materials are also discussed in this paper.关键词：Polymer-based flexible sensing materials;Capacitive pressure sensor;Iontronic pressure sensor;Sensing mechanism;Wearable electronics
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发布时间：2023-09-19 - 摘要：One of the greatest challenges to the forming technology of continuous fiber reinforced polymer composites is quality control, and the shear rheological behavior of tool/ply and ply/ply due to friction is extremely critical during the forming process. This paper is to summarize the work available on literature about frictional rheology of continuous fiber reinforced polymer composites in the molding process, in order to characterize and simulate its deformation mechanism, and ultimately achieve process optimization design. By elaborating the theoretical models and experimental measurement techniques respectively, the measurement methods of the devices and the results were analyzed and discussed. It was found that various factors (temperature, pressure, motion rate, fiber orientation, surface morphology, surface roughness, device structure, friction area) play an important role on the friction rheological mechanism. The research in this field aims to provide a theoretical basis for the processing technologies of continuous fiber reinforced polymer composites, and will also lay a theoretical foundation for the cross development of traditional tribology and rheology.关键词：Polymer composite materials;Forming and processing;Friction;Rheology;Characterization method;Constitutitive model
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发布时间：2023-09-19 - 摘要：Upconversion particle-assisted near-infrared photopolymerization (UCAP) has shown promising applications in 3D printing. However, due to the low fluorescence efficiency of upconversion particles, the surface of the printed material suffers from severe oxygen inhibition effects. It reduces the printing speed and printing accuracy. In this study, we overcome this difficulty by introducing thiol-ene photopolymerization monomers into the ink design. By optimizing the printing ink formulation, it was found that the ink with secondary thiol-olefin monomer as the light-curing substrate and 4% thixotropic agent addition exhibited the best thermal stability and printing performance. By using this optimal ink formulation for 3D printing, fast printing of black lattice structures and unsupported spiral structures at 25 mm/s printing speed (1 mm diameter nozzle) was successfully achieved. The mechanical properties of the printed material were comparable to those of the molded material, with a tensile strength of 55 MPa.关键词：Near-infrared photopolymerization;Upconversion particle;Direct ink writing;Thiol-ene photopolymerization
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发布时间：2023-09-19 - 摘要：The bioderived chitosan was modified by carbon dioxide (CO2) and utilized to prepare hydrogel beads loaded with silver nanoparticles (AgNPs). The reaction intermediate between CO2 and the amine group of chitosan, carbamic acid group, was proven effective in increasing the coordination site of chitosan for silver. The conductivity and viscosity changes of the solution confirmed the occurrence of the reaction and that the largest amount of carbamic acids was formed at 30 min. The scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared resonance (ATR-FTIR) results confirmed that the silver loading capacity of chitosan after modification with CO2 was doubled. The silver content was the largest and the AgNPs size was the smallest when the reaction time was 30 min. The results also showed that the Ag atoms were coordinated with the N and O atoms of chitosan. The prepared silver-loaded chitosan (CS-Ag) hydrogel beads were applied to catalyze the methylene blue reduction reaction. The reaction rate catalyzed by CO2-modified CS-Ag beads were greater than that catalyzed by unmodified beads under the same conditions, and the beads modified for 30 min performed the best. Also, the reactions catalyzed by CO2-modified CS-Ag beads were more sensitive to temperature, and with the increase of reaction temperature, the difference of reaction rate became larger, up to about three times of the original one.关键词：Chitosan;Silver nanoparticles;Hydrogel bead;Dye reduction
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发布时间：2023-09-19 - 摘要：In order to explore the effect of pre-stretching treatment on the conductivity and sensing properties of polypyrrole elastic conductive filaments, polypyrrole-coated fibers with different weight gain ratios were obtained by pre-stretching the elastic filaments to different degrees during pyrrole polymerization. Its microscopic morphology was observed by scanning electron microscopy, and the electrical and sensing performances were tested and analyzed. The research results show that the resistance decreases with the increase of pre-stretch ratio (>70%). At 10% pre-stretch ratio, the polypyrrole layer is smoother, but has the best strain sensing performance: in the range of 0~2 cN, the internal sensitivity is high up to 7.68/N, and the sensitivity decreases and stabilizes at about 1/N after exceeding 2 cN. Both the repeatability experiment and the finger bending test show that the conductive filament pre-stretched by 10% has good sensitivity and sensing stability, and the resistance change rates are 24.71% and 11.01%, respectively. Therefore, the polypyrrole composite elastic filament with this structure is expected to be used in the detection of human motion and physiological signals. The elastic conductive yarns with higher pre-stretch ratios have a wrinkled structure on the surface, so they have the stable resistance value as stretched, which can be used in wires and electrodes.关键词：Pre-stretching;Polypyrrole;conductivity;Sensing property;Finger motion detection
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发布时间：2023-09-19 - 摘要：Super-hydrophobic polyurethane porous materials (PU-Hex) were prepared via thermally induced phase separation (TIPS) using PU as raw material and n-hexane as segregation reagent. The surface composition and pore structure of the materials were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM),thermogravimetric analysis (TGA) and nigrogen adsorption and desorption analysis. The results showed that the benzene rings of PU chain were enriched on the surface, while the pore structure and thermal stability remained unchanged. The surface water contact angle reached as high as 149°. PUHex was capable of absorbing various oils solvents from oil/water mixtures selectively, and the saturated absorption performance reached 11.33 times of its own weight. The adsorption rate of soybean oil by PU-Hex porous materials was 0.199 g·g-1·min-1, larger than that of original PU porous materials. The afterward fabricated tubular PU-Hex porous materials could demulsificate emulsion rapidly, and clean water was separated from the emulsion. Moreover, the separation performance of the tubules restored quickly and easily, rendering them desirable candidates for oil-water emulsion treatment.关键词：Polyurethane porous material;n-hexane;Induction;Thermally induced phase separation;Oil/Water separation
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发布时间：2023-09-19 -
Preparation of Ni3S2/Amidoximated Polyacrylonitrile Composites and Its Hydrogen Evolution Properties
摘要：Catalytic activity and cycle stability are the critical factors in improving the performance of the hydrogen evolution reaction (HER) of Ni3S2 electrocatalyst. In this study, Ni3S2/amine oxime polyacrylonitrile polymer (AOCF) composites were successfully prepared from nickel chloride, thiourea, L-cysteine, and AOCF by solvothermal and ligand loading methods. The results of structure and performance characterization show that Ni3S2 forms a coordination bond between Ni and —OH and —NH2 on the AOCF chain, resulting in Ni3S2/AOCF composites. As HER electrocatalysts in acidic media, Ni3S2/AOCF composites exhibit excellent electrocatalytic activity and good cycle stability, with an overpotential of -233 mV, a Tafel slope of 94.7 mV/dec, and cycling stability of up to 50 h at a current density of -30 mV/cm2. As a result, Ni3S2/AOCF composites show the characteristics of high hydrogen evolution performance, low cost, and good stability.关键词：Ni3S2;AOCF;Catalytic activity;Hydrogen evolution performance;Electrocatalyst- 16
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发布时间：2023-09-19 - 摘要：In this paper, the free energy-composition curves and phase diagrams in polymer physics are discussed and interpreted. The free energy-composition curve is presented in 3D illustration, and the phase diagram is displayed and discussed intuitively. The factors influencing the trend of the free energy-composition curve are discussed from the point of view of mathematics. It is further clarified that the common tangent point is different from the binodal point. It is proven that the composition of separated states after phase separation is the abscissa of the common tangent points of the free energy curve. The proof method is easy enlightening and acceptable for students to understand, and it can be a useful supplement to the knowledge system and teaching ideas of phase separation thermodynamics in polymer physics.关键词：Phase separation;Phase diagram;Mixing free energy-composition curve;Binodal point;Spinodal point
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发布时间：2023-09-19 - 摘要：The Scatchard-Hildebrand equation is one of the core components of the theory of regular solutions and nonelectrolyte solutions. It also links multiple key points of polymer physics such as the cohesion energy, solubility parameters and even the van der Waals equation. Although the derivation of the equation is not necessary and rare in textbooks, students demand more introduction to its origin and development history. Based on such introduction, students may better understand and utilize this equation. In this paper, the development and derivation process of the equation are summarized to assist the teaching. It serves as a supplementary to previous professional derivations, and a vivid introduction from the perspective of its inventors.关键词：Polymer physics;Scatchard-Hildebrand equation;Cohesive energy;Solubility parameter;Hildebrand
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发布时间：2023-09-19 - 摘要：In the textbook of Polymer Physics, "rubber elasticity" is an important chapter linking the statistics of conformation of long-chain macromolecules and mechanical behaviors of polymer materials. In the current textbooks, rubber elasticity is introduced following the Rehner-Flory "four chains" model to present conformational entropy and contraction force of network of Gaussian chains by formulating entropy of single Gaussian chain in the first step and summing entropies of all Gaussian chains under assumption of affine deformation under constant volume in the second step. In general, the approximations and academic disputes involving the modellization are not referred to. Under the prevailing teaching practice, some students may believe that vulcanizates behave like network of Gaussian chains and some technicians may try to develop the so-called reversibly deformable flexible electronics by designing the so-called ideal network structure. Here reviewed are the modellization of network of Gaussian chains and the involved theories, approximations and disputes, aiming to point out that the network of Gaussian chains is only a model concepted under many assumptions and that the model cannot be used to describe the structure of vulcanizates.关键词：Rubber elasticity;Network of Gaussian chains;Network chains;Displacement length;Conformational entropy
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发布时间：2023-09-19
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