最新刊期
- 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 - 摘要：A regioselectively substituted cellulose derivative with bulky pendants at the 6-position, that is the cellulose-[2,3-(3,5-dimethyl)-6-(4-(4-(3-(9-ethyl-9H-carbazole-3)ureido)benzyl))]phenylcarbamate (Cel-1), was successfully synthesized using cellulose as substrate by 6-position-protection method and carbamoylation. The 1H NMR spectrum and elemental analysis data indicated that the cellulose derivative was structurally regular with almost complete substitution as expected. The fluorescent recognition property of Cel-1 was then evaluated in detail based on twelve metal ions. The results indicated that the bulky cellulose derivative (Cel-1) could realize excellent dual-mode recognition to both Fe3+ and Cu2+ with high sensitivity and high selectivity in the DMSO/H2O system, together with high anti-counterfeiting ability to the other ten metal ions tested in the study. Especially, the limits of detection of Cel-1 for Fe3+ and Cu2+ in both fluorescence and UV-visible modes were lower than the maximum acceptable concentrations of the two ions in drinking water as defined by the United States Environmental Protection Agency (EPA). It demonstrated that the obtained bulky cellulose derivative possessed high-efficient and specific fluorescent recognition ability for Fe3+ and Cu2+, which could be used as chemosensors for the rapid recognition and detection of the two metal ions. In addition, the fluorescent ink prepared based on Cel-1 could not be observed under natural light, whereas emitted bright blue fluorescence under ultraviolet light, suggesting its potential in the anti-counterfeiting related field.关键词：Fluorescent sensing;Bulky pendants;Cellulose derivatives;Metal ion recognition;Dual mode detection
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发布时间：2024-04-12 - 摘要：Sulfur dispersion is the most common crosslinking agent for latex vulcanization. However, sulfur dispersion is unstable and its preparation process is complex, and toxic zinc-containing accelerators should be used together for effective crosslinking. In recent years, synthesizing sulfur copolymers through inverse vulcanization of elemental sulfur and vinyl monomers has received widespread attention. Herein, self-emulsified sulfur copolymers (STD) were prepared by inverse vulcanization of elemental sulfur, polysorbide 80 and 1,3-diisopropylbenzene. The effect of monomer feed ratio on the structure and yield of STD was studied. According to laser particle size distribution analyzer and scanning electron microscope measurements, STD emulsion could be stably dispersed in water for a long time with an average size of about 80 nm. Further, STD was used as the crosslinking agent for carboxylated nitrile rubber latex, and the influences of STD content and composition on the properties of crosslinked rubber were systematically studied. The results showed that the fractions of sulfur and polysorbate 80 in STD determine the properties of crosslinked rubber by affecting crosslinking density and plasticizing effect, respectively. Compared with sulfur dispersion, STD emulsion is more stable with smaller micelle size and has higher reactivity, which avoids using toxic zinc-containing accelerators and imparts the crosslinked networks with better mechanical properties, thus exploring new avenue for the green crosslinking of rubber latex and the preparation of high-performance rubber materials.关键词：Inverse vulcanization;Rubber latex;Green crosslinking;Sulfur copolymer
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发布时间：2024-04-12 - 摘要：This study reported that an efficient and controllable ring-opening polymerization of ω‑Pentadecalactone (PDL) by using cyclic trimeric phosphazene base (CTPB) as a catalyst and benzyl alcohol (BnOH) as an initiator. High molecular weight PPDL was obtained after optimizing the experimental conditions. The PPDL film with high molecular weight not only showed similar mechanical properties, crystallinity and high melting point (Tm = 95.5 °C) as polyethylene, but also exhibited the degradability of aliphatic polyesters. Differential scanning calorimetry (DSC) proved that PPDL had good crystallinity. Wide-Angle X-ray Scattering (WAXS) showed that PPDL had a unit cell structure similar to that of commercial high-density polyethylene (HDPE). Moreover, bishydroxyl-end-capped PPDL (PPDL-diol) can be easily prepared via ROP of PDL with BDM as initiator. Then the PPDLs with high molecular weights were obtained by chain extension reactions with diisocyanates and showed enhanced mechanical properties. In addition, we synthesized a variety of random copolymers with different ratios of PDL and ε-caprolactone (ε-CL). The melting points and hydrolysis of the copolymers could be adjusted by changing the ratio of ε-CL. The melting points of the obtained random copolymers could be adjusted in the range of 53.0-95.5 °C by changing the ratio of ε-CL. Finally, the hydrolysis of PPDL copolyester was achieved under alkaline conditions. Compared with PPDL homopolymer, the hydrolysis of random copolymers showed faster hydrolysis rate and adjustability关键词：Ring-opening polymerization;Degradable polyester;Polyethylene-like polymers;Organobase
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发布时间：2024-04-12 - 摘要：The self-assembly behavior of three regio-isomers, namely the ortho-, meta-, and para-isomers, formed by double chains grafted at different vertices of cage-like molecules, was simulated using the Dissipative Particle Dynamics (DPD) method. The results indicate that a long the varying length of the grafting chains the three regio- isomers exhibit inconsistent regulation of the emergence and stability of self-assembled structures. Specifically, when the grafting chains are relatively short, the curvature of the ordered structures self-assembled by the tail chains increases in the order of ortho-, meta-, and para-isomer. In contrast, when the grafting chains are longer, the cage-like molecules in different isomers tend to stack into distinct bicontinuous structures. The simulation results also predict that the temperature of the order-disorder transition (TODT) for the three regio-isomers decreases in the order of ortho-, meta-, and para-, and this trend is consistent with the TODT of the combined regio-isomers. The diverse phase behaviors in the regio-isomers can be understood from the different conformation of the chains and packing of the cage molecules. This study clarifies that the tiny differences in the structural unit can profoundly impact the self-assembled structures, which offers new insights into exploring unconventional order structures self-assembled in soft matters.关键词：Cage-like molecule;Block copolymer;Dissipative particle dynamics (DPD);Self-assembly
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发布时间：2024-04-12 - 摘要：An intumescent fireproof sealing system with room temperature vulcanized silicone rubber (SR) as matrix, sodium silicate (NSH) as expansion filler and ammonium polyphosphate (APP) as flame retardant was designed, and the effects of different modulus expansion agents on the properties of the material were investigated. The SR composites were prepared by blending pouring method. The thermal stability and flame retardancy of SR composites were measured by vertical burning test (UL-94), limiting oxygen index (LOI) and thermogravimetric analysis (TGA). Moreover, the important indexes of the sealing material were measured by expansion test and fire resistance test. The morphology of char residues after UL-94 test and fire resistance test were observed by scanning electron microscopy (SEM). The results showed that the high modulus sodium silicate had better thermal expansion effect, and the 2.8 modulus sodium silicate had the best expansion fireproof performance. The sample with only expansive agent had no grade in the flame-retardant test, but by adding a small amount of flame retardant, the limiting oxygen index increased to 30.9 %, and passed the UL-94 test V-0 grade. The study of mechanism found that the outer layer of the material was transformed into a thin-walled hollow microsphere stacking structure when exposed to fire, forming a strong expansion barrier layer. Concomitantly, the expansion barrier layer efficiently exerts the gas phase flame retardant effect of the flame retardant. In addition, the prepared sample can reach the 3h level of fire sealing test for cracks.关键词：Sealing Material;Room Temperature Vulcanized Silicone Rubber;Ammonium polyphosphate;Sodium Silicate
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发布时间：2024-04-10 - 摘要：Two styrene derivatives ((Z)-2,2,2-trifluoro-1-(4'-vinyl-[1,1'-biphenyl]-4-yl)ethan-1-one O-(3-methylbenzoyl) oxime, OXE-P and (Z)-2,2,2-trifluoro-1-(4'-vinyl-[1,1'-biphenyl]-4-yl)ethan-1-one O-thiophene-2-carbonyl oxime, OXE-S) modified by photosensitive oxime ester group were synthesized. They were characterized by hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry (HRMS). New polymers (POXE-P and POXE-S) were prepared by the reversible addition-fragmentation transfer (RAFT) polymerization, and were further measured by gel permeation chromatography (GPC), giving molecular weights (Mw) of 8.3 and 7.2 kDa, and polydispersity indexes (PDI) of 1.1. Both polymers exhibit good solubility, thermal stability and film-forming ability, which meet the requirements of resist materials. The polymers were dissolved separately in the propylene glycol methyl ether acetate (PGMEA) to form nonchemically-amplified resists (n-CARs). The lithographic performance of the POXE-P resist was examined by e-beam lithography, giving a 50 nm HP (half-pitch) lithographic pattern. The mechanism of POXE-P resist during exposure was investigated by Fourier Transform Infrared Spectrometer (FTIR) and in situ outgassing analysis. It showed that the oxime ester group decomposed during exposure to form carbonyl compounds, CO2, and other small molecules. The cleavage of side chains and the possible crosslinking led to the solubility switch of the polymer, resulting in negative lithographic patterns.
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发布时间：2024-04-03 - 摘要：Based on polymerized thermally activated delayed fluorescence (TADF) small molecules, a series of single white-emitting polymers named P010 ~ P075 have been designed and synthesized by using acridine-benzophenone-carbazole (AcBPCz) as the sky-blue TADF moiety, acridine-naphthalimide-carbazole (AcNICz) as the orange TADF moiety and tetramethylbenzene as the linker between them. After a modulation of the AcNICz content in the range of 1 ~ 7.5%, a part energy transfer can happen from AcBPCz to AcNICz. Consequently, P010 ~ P075 all display a dual spectral profile in the photoluminescence (PL): the sky-blue emission peaked at 482 ~ 492 nm is from AcBPCz, while the orange emission peaked at 590 ~ 602 nm is from AcNICz. And the ratio of sky-blue to orange emission together is found to be decreased gradually with the increasing content of AcNICz. The corresponding solution-processed OLEDs achieve a bright white electroluminescence (EL), revealing a maximum current efficiency of 5.4-16.8 cd A-1 and a maximum external quantum efficiency of 3.0 ~ 6.4%. Noticeably, the EL is obviously dependent on the AcNICz content, consistent with the PL counterparts. Ongoing from P010 to P075, the Commission Internationale d'Eclairage (CIE) coordinates are shifted from (0.32, 0.50) to (0.47, 0.44) and the correlated color temperature (CCT) is reduced from 5910 K to 2797 K. The obtained cold white EL for P010 and warm white EL for P075 are believed to be applicable for different lighting scenes.关键词：OLED;TADF polymers;Single white-emitting polymers;Polymerized TADF small molecules;Emissive color
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发布时间：2024-04-02 - 摘要：Form-stable phase change materials (FSPCMs) are a kind of latent heat/cold energy storage materials and play key role in fields like new energy development, cold chain temperature control and healthcare. Lots of expensive chemicals have been investigated as phase change materials (PCMs) for FSPCMs, however, the application of water, a very cheap and abondance material in our planet, as a phase change cold energy storage material for FSPCMs is neglected. Herein, a kind of hydrogel based on polyvinyl alcohol and polyacrylic acid was prepared at first, and then novel FSPCMs with high latent cold energy storage capacity were obtained by solving the problem of water leakage in the hydrogel through simple surface freeze drying. The latent cold energy storage capacity of the obtained hydrogel-based FSPCMs attained 237 J/g, and the water in the FSPCMs would not volatilize when the temperature was not higher than 50 ℃. The FSPCMs also exhibited excellent anti-leakage performance even it was heavily pressed. Meanwhile, the FSPCMs possessed good long-term thermal reliability and its latent cold storage performance has not changed after 50 freeze-thaw cycles. The FSPCMs also had good temperature control and shaping properties, making it applicable to cold storage, cold chain temperature control, cold compress and other fields. In addition, in order to fully utilize the high porosity of dried hydrogel, exfoliated graphite nanoplatelets (xGnP) were applied to enhance the stability of the hydrogel skeleton with the largest water content, and a novel supporting material with high porosity was obtained by freeze-drying. Then, Erythritol (ET) and PEG6000, two water-soluble PCMs, were selected as representatives, and two types of FSPCMs were prepared by melting impregnation. Both types of FSPCMs possessed very high content of PCMs and very high latent heat storage capacity, which proved that polymer network skeletons of hydrogels were perfect supporting materials for FSPCMs. Consequently, the results obtained in this paper have important value for promoting the application of hydrogel itself and hydrogel materials in the fields of heat energy storage and temperature control.
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发布时间：2024-03-28 - 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. 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. 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 seconds). Mechanical studies show that the obtained material exhibits a strength of ∼33.5 MPa and excellent toughness of ∼188.26 MJ m-3, with a Young's modulus of ∼76.6 MPa. 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.关键词：Elastomer;Covalent organic framework;ultralong room temperature phosphorescence;multiple hydrogen bonds
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发布时间：2024-03-26 - 摘要：Porous polymers with azobenzene skeleton (Azo-POPs), which are characterized by good chemical stability, high specific surface area, and easy functionalization and modification, have shown great application prospects in a number of fields and attracted much attention. In this paper, we summarized the ways of incoporating azobenzene subunits into porous polymer skeletons in recent years, including the condensation polymerization of polyaminoaromatics and poly(nitroso)aromatics, the oxidative coupling polymerization of polyaminoaromatics, the reductive coupling polymerization of poly(nitroso)aromatics and the coupling polymerization of electron-rich aromatics with polydiazonium salts, and so on. Furthermore, the functional groups such as hydroxyl and amine groups have been introduced to the afore-mentioned Azo-POPs, and interesting performance resulted correspondingly. The unexpected irreversible isomerization of tris(β-hydroxyazo)benzene structure to tris(β-keto-hydrazone)cyclohexane in the porous organic polymers was summarized, as well as their special applications in the fields of gas and vapor adsorption and storage, multiphase catalysis, removal of pollutants in water, gas membrane separation and electrochemistry. Finally, the challenges to the development of Azo-POPs are analyzed and pointed out.关键词：Porous organic polymers;Azo-benzene;Hydroxyl-azobenzene;Amino-azobenzene;Tris(β-keto-hydrozo)cyclohexane
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发布时间：2024-03-05
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