最新刊期
- 摘要：Direct recycling of leather waste (LW) into high value-added products has always been a challenge for the leather industry. In this study, a "three source in one " leather-based intumescent flame retardant (PA@LW@APP) was prepared in aqueous solution by electrostatic interaction, using LW rich in nitrogen/carbon elements as a carbon/gas source and ammonium polyphosphate (APP) as an acid source. Then PA@LW@APP was introduced into thermoplastic polyurethane elastomer (TPU) by melt blending. It was found that when the addition content of PA@LW@APP is 5 wt%, TPU5 can achieve UL-94 V-0 rating. The flame retardant TPU forms an intumescent char layer during cone test that blocked the external fire source and combustible gas, showing excellent heat suppression, smoke suppression and char-forming ability. Compared with pure TPU, the peak heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) of flame retardant TPU containing 15 wt% PA@LW@APP were reduced by 71.1%, 36.0% and 51.4%, respectively. In addition, the encapsulated structure of PA@LW@APP make it well dispersed in the TPU substrate and not easy to agglomerate, and the flame retardant TPU maintain good tensile toughness. This work not only realizes the high-value recycling of leather waste through a green and simple method, while also giving TPU excellent flame retardant properties.关键词：Thermoplastic polyurethane;leather waste;intumescent flame retardant;Mechanical properties;high-value recycle
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发布时间：2024-05-16 - 摘要：To address the challenges associated with the inadequate barrier properties and reduced elastic modulus of poly(butylene adipate-co-terephthalate) PBAT, a series of PBAT/poly(butylene carbonate) (PBC)/epoxidized soybean oil (ESO) composites were prepared by melt blending ESO as a compatibilizer and PBC as the second component with PBAT. The effects of ESO content and PBC content on the thermal properties, crystallization properties, mechanical properties, and barrier properties of the composite materials were investigated through fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and other relevant characterization tools. Additionally, the compatibility mechanism of ESO on the composite materials was discussed. The results demonstrated that the epoxy groups in ESO enhanced the compatibility of PBAT and PBC through a ring-opening reaction with the end groups of PBAT and PBC. Furthermore, the crystallization properties and thermal stability of the composites were improved. SEM images showed that the delamination in the composites disappeared after the addition of ESO, and a linear fiber structure appeared, further proving the compatibility enhancement. At the same time, the addition of ESO significantly improved the ductility of the composites. The elongation at break of PBAT/PBC composites increased from 353% to 805% when the ESO content in the composites was increased from 0% to 7.0%; meanwhile, PBC and ESO show an excellent synergistic effect in improving the elongation at break of the composite materials. In addition, the addition of PBC can significantly improve the barrier properties and stiffness of PBAT/PBC composites. The oxygen and water vapor barrier properties of composites increased by 73% and 64.7%, respectively, as the PBC content increased from 0 wt% to 80 wt%. Furthermore, the modulus of elasticity increased by 254%. The comprehensive performance of PBAT was notably improved through the incorporation of PBC and ESO as modifying materials, thereby promising to broaden the application fields of PBAT.关键词：Poly(butylene adipate‐co‐terephthalate) (PBAT);Poly(butylene carbonate) (PBC);Compatibility;Biodegradable plastics;Barrier performance
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发布时间：2024-05-16 - 摘要：We utilized a low-cost polymer donor P(Cl) with a simple non-fused ring acceptor 2BTh-2F as the active layer material for device preparation. Through careful selection and optimization of additives, we have significantly enhanced the microstructure and interfacial interactions of the device, resulting in an excellent power conversion efficiency (PCE) of 14.21%. The device achieves an open-circuit voltage (VOC) as high as 0.861 V, a short-circuit current density (JSC) of 23.18 mA/cm², and a fill factor (FF) of 71.21%, which exceed the performance of the control without additives (12.51%). It is noteworthy that this efficiency value is one of the highest achieved to date based on the pairing of a simple polymer donor material with a simple non-fused ring acceptor material. Our work not only demonstrates the great potential of low-cost materials in the preparation of high-performance devices, but also proves that dual low-cost, high-efficiency devices with polymer donors and small-molecule acceptors can be realized by finely tuning the morphology of the blended film and deeply studying the film-forming process. This work opens up a new path for the future development of low-cost and high-performance photovoltaic devices, which is of great scientific significance and practical application value.关键词：Organic solar cell;Simple donor;Non-fused ring acceptor;Photovoltaic conversion efficiency
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发布时间：2024-05-15 - 摘要：The catalytic depolymerization and recycling of aliphatic polycarbonates have attracted increasing attention in recent years. The crystalline structure of aliphatic polycarbonates impedes the penetration of solvents and catalysts, thereby reducing depolymerization activity. Additionally, the thermal depolymerization reaction process is complex, accompanied by numerous side reactions and a lack of high selectivity in recovering the target product. Consequently, the depolymerization behaviors and products of aliphatic polycarbonate are highly complex and influenced by numerous factors. In this study, we investigated the depolymerization reactions and behaviors of poly(butylene carbonate), poly(pentylene carbonate), and poly(hexylene carbonate) under various catalysts and reaction conditions using intrinsic melting methods. Furthermore, the differences in product selectivities were characterized through NMR spectroscopy. The results demonstrated that potassium tert-butoxide and sodium tert-butoxide were found to be highly effective catalysts for the depolymerization of poly(butylene carbonate), with distinct product selectivities. Specifically, potassium tert-butoxide was observed to favor the depolymerization process, resulting in the production of primarily fourteen-membered cyclic dimer (7CC)2. In contrast, sodium tert-butoxide exhibited a preference for the generation of seven-membered cyclic carbonate monomer (7CC). Theoretical calculations indicated that the production of (7CC)2 was a more dominant reaction pathway than the generation of 7CC. Increasing the reaction temperature was found to be favorable for improving the selectivity for 7CC production. Poly(pentylene glycol carbonate) and poly(hexylene glycol carbonate) were observed to only produce the corresponding sixteen-/eighteen-membered cyclic dimers, with no eight-/nine-membered cyclic monomers being produced. The objective of this research is to provide an experimental and theoretical basis for the further development of efficient depolymerization and recycling methods for aliphatic polycarbonates.关键词：Aliphatic polycarbonate;Catalyst;Depolymerization and recycling;Cyclic carbonate
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发布时间：2024-05-13 - 摘要：Non-conjugated photoluminescent polymer PMVN with aggregate induced luminescence was successfully prepared by ammonia treatment. PMVN not only exhibited photoluminescent properties in both solution and solid state, but also shows different colors and fluorescence characteristics when dissolved at different temperatures (room temperature, or 85 °C). Microstructure analysis shows that the structures of PMVN-RT and PMVN-85 is basically the same, yet their fluorescence clusters are significantly different, which may attribute to their different fluorescence characteristics. In addition, the color of PMVN-RT changed to green after heating, while the fluorescence clusters, solution color and fluorescence characteristics of PMVN-85 showed a trend of transforming into PMVN-RT after being placed at room temperature for 72h. PMVN is a thermochromic photoluminescent polymer with reversible transformation characteristics. Besides, composite fluorescent hydrogels can be prepared, and have application prospects in many fields such as temperature sensor, biosensor, disease diagnosis, cell imaging, bionic drive and environmental monitoring.关键词：poly(maleic anhydride-alt-vinyl acetate) (PMV) and its derivatives;fluorescent hydrogel;self-stabilized precipitation polymerization;photoluminescent clusters;blue and red emission;aggregation induced emission
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发布时间：2024-05-13 - 摘要：Polyamide composite nanofiltration membranes prepared by interfacial polymerization have been widely used in brackish water purification, wastewater treatment and solvent recovery. However, it remains a challenge to further enhance the membrane performances by optimizing their structure due to the rapid reaction rate and poor controllability of the conventional interfacial polymerization. In this work, we report a facile strategy to fabricate polyamide composite membranes with improved nanofiltration performance by using lithium chloride as an additive in interfacial polymerization to regulate the membrane structure. The synthesized polyamide layers show a reduced harmonic amide bond density and an increased pore size from 0.51 nm to 0.59 nm, while the morphology, chemical structure, surface charge, and surface hydrophilicity remain almost unchanged under the optimal addition of lithium chloride at 1.25 g·L-1. The resulting structure endows the polyamide composite membrane with a 17% enhanced water permeance, reaching up to 216 L·m-2·h-1·MPa-1, while maintaining a high rejection of Na2SO4 above 98.8%. In addition, our prepared nanofiltration membranes demonstrate excellent performance stability when operated under various applied pressure, across a wide concentration range of feed solution, and during a 120-h long-term filtration process, indicating the potential of our membranes in practical applications.关键词：Interfacial polymerization;Polyamide;Lithium chloride;Polyamide composite membrane;Nanofiltration
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发布时间：2024-05-13 - 摘要：Polycaprolactone polyurethane (PCL-PU) has excellent mechanical properties, good biocompatibility and biodegradability, and is widely used in biomedical materials and other fields. However, the domestic production capacity of polycaprolactone diols is unable to meet the production demand of the polyester-based polyurethane industry. The search for alternatives with comparable properties to polycaprolactone-based polyurethanes is of great research importance. Therefore, in this paper, three polycaprolactone (PCL-diol) and polycarbonate (1,4-butanediol) ester polyols (PC-diol) with different relative molecular masses were prepared using Lewis pair-catalyzed controlled ring-opening polymerization, respectively. The structures of the two polyester diols were characterized by nuclear magnetic resonance hydrogen spectrometry (1H NMR) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis (MALDI-TOF MS). PCL-PU and polycarbonate polyurethane (PC-PU) were synthesized by reacting two polyester diols with 2,4-toluene diisocyanate (TDI) and chain extender 1,4-butanediol (BDO), respectively. The thermal properties, crystalline behaviors, and mechanical properties of the two polyurethanes were further investigated in a comparative manner by thermogravimetric analysis, differential scanning calorimetry analysis, and stress/strain test. The results show that PC-PU has similar thermal stability and thermal decomposition process as PCL-PU, and the initial decomposition temperature of both polyurethanes is > 260 ℃, and both of them have two thermal decomposition stages. PCL-PU has a faster crystallization rate, while PC-PU has a slower crystallization rate. Compared to PCL-PU, PC-PU has higher elongation at break (> 1200%) and breaking strength (> 45 MPa). This paper provides a scientific basis and rationale for the creation of PC-PU with comparable properties of PCL-PU, and provides impetus for the development of the polyurethane industry.关键词：Polycaprolactone;Polycarbonate;polyester diols;Ring-opening polymerization;Polyurethane
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发布时间：2024-05-13 - 摘要：Amidst growing demands for environmental protection and sustainable development, there is an urgent need within the industry for alternatives to traditional chemical adhesives, which are implicated in environmental contamination and health hazards. This study introduces an antifreeze silk fibroin bioadhesive designed to address the performance deficits of conventional bio-based adhesives in frozen conditions. The synthesis of this novel silk-derived adhesive employs a dual-stage process: initially crafting a silk fibroin-based adhesive matrix, followed by its integration with an aqueous solvent system to formulate the bioadhesive. This approach enables the long-term storage of protein powders under ambient conditions, with the flexibility of formulation and application upon demand. Additionally, the adhesive strength is readily adjustable through the modulation of substrate concentration. The adhesive efficacy is principally reliant on the hydrogen bonding capability, with the quantity of hydrogen bond sites provided by silk fibroin critically influencing the protein adhesive's binding properties. Incorporation of tannic acid, known for its strong affinity with silk fibroin, prevents the transition of silk fibroin chains from a random coil to a β-sheet, thereby preserving the bioadhesive's strength. The study further refines the silk fibroin to tannic acid ratio and solvent composition, opting for a binary solvent system of ethylene glycol and water. This choice markedly enhances the solubility of the silk fibroin bioadhesive and significantly depresses its freezing point, augmenting its antifreeze capabilities and facilitating substrate bonding at low temperatures. The adhesive also exhibits exceptional low-temperature stability and adaptability to fluctuations in ambient temperature. Experimental validations demonstrate that this bioadhesive surpasses the adhesive performance of conventional commercial chemical adhesives and other bio-based adhesives over a broad temperature range from -24°C to room temperature. Consequently, the antifreeze silk fibroin bioadhesive developed in this study, with its eco-friendliness, biodegradability, and exceptional adhesive performance under extreme low-temperature conditions, shows great potential for applications in key areas such as packaging, biomedical, and environmental protection.关键词：Silk fibroin;Tannic acid;Antifreeze;Bioadhesive;Eco-friendly
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发布时间：2024-05-13 - 摘要：In this paper, a soluble polyimide (PI) was synthesized in a high-temperature one-step process using fluorinated dianhydride 4,4'-(hexafluoroisopropylidene)bis(phthalic anhydride) (6FDA) and reactive carboxyl-containing diamine 3,5-diaminobenzoic acid (DABA) as monomers, with the self-enhancing photosensitive cinnamoyl group grafted on the carboxyl group of the PI through the esterification reaction. Three kinds of photosensitive polyimide resins with different molecular weights, PI95, PI97.5 and PI100, were synthesized by controlling the molar ratio of 6FDA and DABA. The photolithographic process parameters of the three kinds of photosensitive polyimides with different molecular weights were systematically explored, and the PI97.5 sample was preferred according to the quality of the photolithographic pattern. The sensitivity of the PI97.5 sample is 785 mJ/cm2, the resolution is up to 7 μm, and the line width is up to 14 μm. The 5% weight loss temperature of the cured film is higher than 340 °C, and the glass transition temperature is up to 274.2 °C, and it shows good mechanical properties. The results provide a research basis for the development of new negative photosensitive polyimide photoresists.
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发布时间：2024-05-10 - 摘要：This research comprehensively examines the thermodynamic behavior and conformational changes in polyethylene (PE) and its blends with supercritical carbon dioxide (scCO2) under shear flow conditions using Non- Equilibrium Molecular Dynamics (NEMD) simulations, which uncovers the influence of scCO2, acting as a plasticizer, on the thermodynamic and conformational properties of PE. The study reveals that scCO2 diminishes intermolecular forces and shear stress within the system, leading to a reduction in viscosity and alterations in the conformational parameters of PE molecular chains. These changes result in an increased free volume and curling of the molecular chains, with a notable decrease in molecular orientation alignment under shear, thereby, enhancing the system's dynamic properties and thermal stability. By analyzing parameters such as stress (τxy and σv)-strain(γ) curves, mean square end-to-end distance (Rete), radius of gyration (Rg), orientation parameters (P2θ), and the autocorrelation function of the relaxation process under three shear flow, the peak shear stress τxy decreased from 0.18 in the PE system to 0.068 in the PE+scCO2 system at =4.686×10-1τ-1, and both Rete and Rg decreased. The persistence length lp of the PE chains is three times that of the PE+scCO2 system. Additionally, the distribution of the molecular chain dihedral angle's gauche plus conformation is reduced, and the trans conformation distribution has increased. The research elucidates that the presence of scCO2 reduces the system's Rouse time τR by approximately 3.9 times, highlighting the plasticizing effect of scCO2, which could effectively promote the conformational freedom and mechanical adaptability of PE under shear flow. This work not only provides deep insights into the complex interactions between PE and scCO2 but also showcases the potential of utilizing scCO2 as a sustainable processing aid in the development of high-performance polymer materials. The findings offer a theoretical foundation for regulating scCO2-assisted polymer processing techniques and advancing the understanding of the dynamic response of polymer systems to external shear.关键词：Linear polymer;Supercritical carbon dioxide;Non-equilibrium molecular dynamics;Shear orientation;Shear flow;Plasticizing effect
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发布时间：2024-05-10 - 摘要：The addition of inorganic fillers has been deemed as an effective strategy for reducing the mold shrinkage of polypropylene (PP). However, the current understanding on the underlying mechanisms is still unclear. In this work, taking talc filled isotactic PP (i-PP) as an example, the effect and mechanisms of inorganic particles on the linear shrinkage of injection-molded i-PP products were investigated theoretically and experimentally. The results indicate that, at low contents (<6 vol%) of talc, the linear shrinkage of the injection-molded products in both in-plane (i.e., along the machine direction MD and transverse direction TD) and out-of-plane directions (i.e., along the thickness direction ND) is found to decrease linearly with increasing talc content. This is consistent with the theoretical prediction. However, at high contents (>6 vol%) of talc, the change trend of the linear shrinkage deviates significantly from the theoretical curves. The in-plane shrinkage decreases remarkably, while the out-of-plane shrinkage remains almost unchanged. Further analysis indicates that the talc plates in the injection-molded products show a strong tendency to align along the MD-TD plane and induce the growth of i-PP lamellae perpendicular to their surfaces. Accordingly, the dense talc network promotes the formation of highly oriented i-PP lamellae perpendicular to the MD-TD plane, ultimately leading to a much lower in-plane linear shrinkage but a higher out-of-plane shrinkage as compared to the theoretical values. Achieving low in-plane linear shrinkage is particularly beneficial for the development of large-sized thin-walled products. Our work not only breaks through the current knowledge (the shrinkage of composites is decreased based on the increased volume fraction of fillers) and gives a new insight on the role of the filler-induced orientation crystallization in tailoring the shrinkage of PP products, but also provides a solution for the development of low-shrinkage PP materials.关键词：Polypropylene;Shrinkage;Crystallization
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发布时间：2024-05-06 - 摘要：High environmental tolerance is a critical requirement for coating applications, particularly in automotive paint. This study successfully fabricated ordered porous photonic microspheres with poly(methyl methacrylate) (PMMA) as the framework using an organized spontaneous emulsification (OSE) mechanism, showing vibrant and adjustable structural colors. PMMA with narrow molecular weight distributions was synthesized via atom transfer radical polymerization (ATRP), and the efficient removal of terminal double bonds resulting from disproportionation termination was achieved through thiol-ene click reactions. Additionally, PMMA macromonomers with norbornene units were prepared through esterification reactions. By employing sequential ring-opening metathesis polymerization (ROMP), (poly(norbornene-g-PMMA)-b-(poly(norbornene-g-PEO)) (PMMA-b-PEO) bottlebrush block copolymers (BBCPs) were successfully synthesized with tunable number-average molecular weights ranging from 174 to 359 kDa and low PDIs below 1.2. In the OSE process, bio-based and environmentally safe anisole was utilized as the oil phase instead of toluene, enhancing the safety and eco-friendliness of the material preparation process, eliminating potential harmful residues, and facilitating large-scale production and application. PMMA-based structural color pigments are anticipated to demonstrate outstanding weather resistance and offer significant potential for applications like automotive paint coatings.关键词：Block copolymer;Self-assembly;Ecofriendly materials;Structural color
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发布时间：2024-05-06 - 摘要：The copolymerization of ethylene and 5-hexen-1-ol (M2) masked by 1.1 equivalents of AliBu3 is carried out by four rare-earth metal catalysts bearing different steric hindrances: (Flu-CH2-Ph)Sc(CH2SiMe3)2(THF) (1)，(Flu-CH2-C5H4N)Sc(CH2SiMe3)2 (2), (Flu-CH2CH2-NHC-C6H2Me3-2,4,6)Sc(CH2SiMe3)2 (3), (Flu-CH2CH2-NHC-C6H4Me)Sc(CH2SiMe3)2 (4). Among them, complex 1 shows the highest catalytic activity (1.32×106 g·molSc−1·h−1) but gives pure polyethylene without detectable M2 unit, and, in contrast, complex 2 is nearly inert. Under same conditions, the bulkier complex 3 shows moderate activity (0.38×106 g·molSc−1·h−1) and low comonomer incorporation (0.7 mol%). On switching to the bulkiest complex 4, the copolymerization process is obviously promoted with a catalytic activity of 1.24×106 g·molSc−1·h−1 and generates a copolymer with 1.8 mol% M2. For the polar vinyl monomers having different CH2 spacers between polar and vinyl groups, complex 4 exhibits the best catalytic performance for the copolymerization of ethylene with 10-undecene-1-ol with the highest catalytic activity (11.91×106 g·molSc−1·h−1) and the strongest incorporation ability (4.9 mol%). The influence of reaction conditions such as comonomer concentration, polymerization temperature and ethylene pressures on the catalytic performance of complex 4 are screened. The microstructures and thermal properties of the resultant copolymers are well-characterized by NMR, GPC and DSC.关键词：Rare-earth metal;Polar monomer;Copolymerization;Functional polyolefin;Ethylene
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发布时间：2024-05-06 - 摘要：Low-foaming nonionic Gemini surfactants are widely used in industrial cleaning and photoresist development. In this study, three low-foaming nonionic Gemini surfactants are synthesized by using 2,5-di-tert-pentylbenzene-1,4-diol and ethylene oxide as raw materials via ring-opening reaction under alkali-catalyzed conditions. The surfactants, named P1, P2, and P3, have different polyoxyethylene chain lengths of 6, 7, and 8, respectively. The surface tension, critical micelle concentration (CMC), wettability, emulsifying, and foaming properties of the three Gemini nonionic surfactants are carefully investigated. The surface tension of P1, P2, and P3 decreases with increasing concentration and remains unchanged when CMC is reached. While at the same concentration, the surface tension increases with the increase of polyoxymethylene chain length due to increased hydrophilicity. The CMC of P1, P2, and P3 are 1.225 mmol/L, 1.016 mmol/L, and 0.70 mmol/L respectively, decreasing with the increment of polyoxymethylene chain length. The contact angle of P1, P2, and P3 decreases with increasing concentration and remains unchanged when the concentration is higher than CMC. The contact angle increases with the increase of polyoxymethylene chain length at the same concentration. The emulsion stability of P1, P2, and P3 increases with increasing concentration and it increases with the increasement of the polyoxyethylene chain length at the same time. The initial foaming volume of P1, P2, and P3 increases with increasing concentration and the chain length of polyoxymethylene at the same concentration. In particular, P1 has the lowest initial foaming volume, which is one percent of the conventional nonionic surfactant Tween-80, exhibiting excellent low-foaming properties. P2 and P3 also show good low-foaming ability, with less than 20% of the foaming ability of conventional surfactant Tween-80. Overall, the three Gemini surfactants offer excellent low-foaming properties while reducing surface tension, making them well-suited for real-world applications such as industrial cleaning and developer fluids.关键词：Nonionic Gemini surfactants;Low-foaming;Surface tension;Wettability;Emulsifying property
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发布时间：2024-05-06 - 摘要：Controlled radical polymerization has aroused considerable attentions during the past decades due to its ability to adjust the polymer chain structure such as molecular weight, molecular weight distribution, composition, and topology. Transition metals compounds such as copper, iron, ruthenium, nickel, etc have been extensively explored. While the effect of the auxiliary ligands on the polymerization behaviour was rarely investigated. Especially for titanium complexes, only metallocene titanium chloride Cp2TiCl2 was examined under the reduction by Zinc. Herein, the binary systems composed by constrain geometry construction trivalent titanium complex (1) and 1-bromo-1-phenylethane (I1), (2-bromo-2-propanyl)benzene (I2) and 1-iodo-1-phenylethane (I3), respectively, were employed to catalyzed radical polymerization of methyl methacrylate (MMA). The influence of initiators on the molecular weight and molecular weight distribution was assayed. The kinetic study of MMA polymerization initiated by 1/I1 indicated linear relationship between MMA conversion and polymerization time, suggesting zero order dependent on MMA concentration. While with the increase of monomer conversion, the molecular weights of the afforded polymers have no obvious change. In addition, with the increase of the ratio of MMA to I1 while keeping the MMA concentration as constant, the molecular weight of the corresponding polymer increased despite the MMA conversion decreased. Meanwhile, with the decrease of the polymerization temperature, the molecular weight of the afforded polymer increased. These results suggested that the polymerization performed in slow initiation, fast propagation. This is consistent with the typical radical polymerization mechanism, but different from those of atom transfer radical polymerization (ATRP) and organometallic mediated radical polymerization (OMRP) which are mediated by organometallic complexes. The above results indicated that the auxiliary ligand has a significantly effect on a radical polymerization process.关键词：Radical polymerization;Trivalent titanium complex;Methyl methacrylate
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发布时间：2024-05-06 - 摘要：Semitransparent organic solar cells (STOPV) are a widely acknowledged solar energy conversion technology that can simultaneously absorb invisible light for energy production while allowing visible light transmission for transparency. However, regarding STOPV integrated on building to reach practical application in the future, the harmonious unification of power conversion efficiency (PCE), average photopic transmittance (APT), and the infrared-light rejection rate (IRR) must be achieved. In contrast to traditional single-optimization strategies, we present an approach to enhance STOPV performance by using a ternary strategy coupled with multiple optical modulation engineering. On the materials level, by combining the wide bandgap donor PM6 and two near-infrared acceptors owing similar absorption but different end groups combinations (symmetric molecule BTP-eC9 and asymmetric molecule BTP-S9), we have optimized the efficiency of a single-junction ternary opaque organic solar cell to 18.66%. On the device level, we propose a triple optical manipulation method by integrating an anti-reflection layer (ARC), a tellurium dioxide (TeO2) optical layer, and a bandpass filter (BF) into the original STOPV structure, to address the see-saw effect among PCE, APT and IRR. Ultimately, our optimized STOPV achieved a PCE of 12.82% and APT of 35.70%, causing a light utilization efficiency (LUE) of 4.6%, and an infrared-light rejection rate of 96.8%, ranking one of the highest performance multifunction-STOPV.关键词：Semitransparent organic solar cells;optical manipulation;tellurium dioxide;near-infrared light insulation;photovoltaic building integration
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发布时间：2024-05-06 - 摘要：With the gradual increase of environmental protection requirements, the utilization of highly toxic organic solvents has become the main factor restricting the production and application of polyurethane-based (PU) transparent coatings, and enabling PU alcohol solubility by structural design is an effective strategy for preparing environmentally friendly transparent coatings. In this paper, poly (propylene oxide diol) was used as the soft segments, and the alcohol solubility and transparency of PU coatings were imparted by introducing the alicyclic structure of isophorone diisocyanate into the hard segments. The chemical structure of the alcohol-soluble PU coatings was characterized by Fourier transform infrared spectroscopy, the alcohol-soluble and optical properties were characterized by ultraviolet-visible spectrophotometry, the hydrophobicity was observed by static contact angle test, the thermal stability was determined by thermo-gravimetric analyzer, and the effect of the content of the hard segments on the mechanical properties was analyzed by electronic universal testing machine. Furthermore, the applied properties were investigated by scratch tests and corrosion resistance measurements. The results show that the ring structure with large spatial site resistance makes the hydrogen bonding between urethane groups in the hard segments weak, and the hydrogen bonding between ethanol and urethane groups promotes the solubilization of the PU coatings, which in turn shows favorable alcohol solubility. The amorphous state of the soft and hard segments resulted in good transparency, but with the increase of the hard segments content, the microphase-separated degree of the PUs increased, which resulted in a decrease in the light transmittance of the coatings, a slight decrease in the hydrophobicity, and a significant increase in the tensile strength. The prepared alcohol-soluble PU-based transparent coatings have excellent hydrophobicity, thermal stability, anti-peeling and corrosion resistance, and are expected to be used in optical devices, high-end glass instruments and other applications.关键词：Polyurethane;Cyclic hard segment;Alcohol soluble;Hydrophobic;Transparent coating
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发布时间：2024-05-06 - 摘要：Polypropylene (PP) has the advantages of low cost, thermoplastic processing and good biocompatibility, and is widely used in the research of household appliances and medical devices. However, it has rarely been used in the preparation of capacitive pressure sensors. In this research, thermoplastic polyurethane (TPU)/PP blends were prepared by melt blending method, the prepared blends were foamed by supercritical carbon dioxide batching foaming technology. The microstructure and mechanical performances of the prepared TPU/PP blends and their foamed samples were characterized. Based on this, the effects and their mechanism of TPU on the mechanical and foaming properties of the blends and thus on the sensitivities of the sensors were analyzed. The results showed that TPU droplets were uniformly distributed in PP matrix. The deformation abilities of the blends were significantly improved by the TPU, and the values of modulus of the TPU/PP blends were much lower than that of the PP. In addition, the melt strengths of the blends were also improved by TPU. And thus, the cellular structures of the foamed TPU/PP samples were improved: the solid area and wormlike-connected cellular structure were significantly reduced or even disappeared in the foamed TPU/PP samples. Therefore, the foamed TPU/PP samples showed stronger deformation abilities, and the values of S of their corresponding sensors were higher. The values of S of the sensor for TPU/PP blend with 30 wt% TPU are 2.5 times (0~17 MPa) and 18.8 times (17~25 MPa) that for pure PP, respectively. By foaming the TPU/PP blend with 30 wt% TPU, the S of the corresponding sensor in the lower pressure range was further increased by 4.1 times. The application testing results show that the prepared sensor reveals good application prospect in detecting human movements such as walking, sitting and grasping.关键词：Polypropylene;Supercritical carbon dioxide foaming;Mechanical properties;Capacitive pressure sensor;Sensing performance
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发布时间：2024-05-06 - 摘要：As the display industry evolves, the research and development of colorless transparent polyimide (CPI) films for use in flexible display covers have become increasingly prominent. This study leverages commercial anhydrides and diamine monomers to fine-tune the main chain structure, fluorine content, and intermolecular hydrogen bonding, thereby achieving an equilibrium among transparency, dimensional stability, thermal resistance, and mechanical strength of the films. The produced CPI-2-TF film showcases exceptional optical average transmittance (Tav>88%), along with minimal coefficients of thermal expansion (CTE) (<13 × 10-6 K-1), elevated glass transition temperatures (Tg) (≥380 ℃), and superior mechanical properties. These attributes establish a robust foundation for the commercialization and mass production of CPI. Moreover, this study specifically examines the bend-durability of CPI-2-TF. After 200k bending cycles, the film maintained over 99% of their original average transmittance (Tav) and exhibited a mere 4% decrease in mechanical properties. Upon extending the bending to 400k cycles, the films retained virtually unchanged optical performance and over 92% of their mechanical integrity, demonstrating high potential for applications in folding screen smartphones and similar devices.关键词：Colorless transparent polyimide;Bend-Durable;Flexible Display Covers;High Temperature-resistance
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发布时间：2024-04-22 - 摘要：To solve the problem that smart wearable flexible sensors wide strain sensing range and high sensitivity is difficult to reconcile, this study employs the wet coaxial spinning method to one-step preparation of a ribbon fiber with a dual conductive network structure. Specifically, carbon nanotubes in the non-solvent-induced phase separation process diffused to the polyurethane, resulting in carbon nanotubes embedded in polyurethane to form a conductive network, which constitutes a dual conductive network with the conductive layer of the carbon nanotubes, and the polyurethane acts as a sheath to provide stretchability. This structure realizes a low initial resistance (387 Ω), a wide strain sensing range (Sensing ε=425%) and a high sensitivity (ε=0-200%, GF=208.8; ε=200-425%，GF=1359.2), and it can also be used as a flexible sensor with an essentially unchanged relative resistance after 12,500 repetitions from 0 to 20% strain. In addition, this flexible sensor has a temperature sensing function (TCR=-0.240%/°C) and corrosion and water washing resistance, which is promising for a wide range of applications such as wearable devices.关键词：Flexible sensor;Dual conductive network;Wide strain sensing range;High sensitivity;Temperature sensing
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发布时间：2024-04-22
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