最新刊期
卷 54 ， 期 8 ， 2023
- 摘要：Dehumidification is closely related to the quality of human life, microbial growth, material corrosion and food storage. Traditional inorganic desiccant materials are not only with low moisture absorption and efficiency, but also with high energy consumption in their preparation and difficult to recycle. Polymer-based hygroscopic materials are expected to overcome these problems and replace conventional hygroscopic materials. In this work, we present a new method for the preparation of polymer-based hygroscopic materials, in which a water-insoluble polymer aerogel containing LiCl was prepared using an aqueous polymer solution containing LiCl. The aerogel can absorb water up to 3.97 g/g at 25 ℃ & 80%RH for 24 h, which is not only much higher than conventional inorganic hygroscopic materials, but also higher than the data reported in the literature for polymer-based hygroscopic materials. The polymer used to prepare this new hygroscopic material is poly(styrene-alt-maleic anhydride), which has aggregation-induced emission properties, so that the hygroscopicity of the new material can be monitored by luminescence intensity.关键词：Hygroscopicity;Polymer aerogel;Aggregation-induced emission;Moisture absorption monitoring
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发布时间：2023-09-25 - 摘要：The crystalline structure of polybutene-1 (PB-1) with low tacticity was investigated by wide angle X-ray diffraction and differential scanning calorimetry after heating to different melting temperatures and non-isothermal crystallization. The formation of form III was observed for the first time in the melt crystallization of PB-1 at atmospheric pressure. It was revealed that the fraction of the form III increased with the melting temperature during the non-isothermal crystallization. The results would be helpful to understand the crystallization and crystal transformation behaviors of PB-1.关键词：Polybutylene-1;Melt crystallization;Form III
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发布时间：2023-09-25
Rapid Communication
- 摘要：Poly(propylene carbonate-co-phthalate) (PPC-P)/poly(butylene adipate-co-terephthalate) (PBAT) blends with various composition ratios were prepared via melt mixing using a torque rheometer. The effects of blending temperature and PBAT content on mechanical behavior, rheological responses, thermal properties, phase morphology and barrier properties of the blends were investigated. Results showed that the properties of PPC-P/PBAT blends were affected by the blend temperature and the composition of the blends. The best performance of the blends is obtained when blending at the temperature where the melt viscosity of PPC-P and PBAT is equivalent, and SEM microphotographs showed that the two polymers in the blends prepared at this temperature could be uniformly dispersed and have good compatibility; Incorporating of PBAT effectively improved the thermal stability, elongation at break and other properties of the blends, but it will also reduce the barrier properties of the material. In a word, PPC-P/PBAT blends with PBAT content of 30 wt%‒50 wt% have excellent tensile and barrier properties and hence have great potential for green food/drug packaging applications.关键词：Carbon dioxide (CO2);Biodegradable plastics;Poly(butylene adipate-co-terephthalate) (PBAT);Barrier performance;Packaging
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发布时间：2023-09-25 -
Polysaccharide Based Injectable Self-healing Hydrogels with Glucose Responsive Drug Release Behavior
摘要：Diabetes mellitus patients commonly suffer from chronic wounds, facing amputation and mortality risk. Hyperglycemia in the diabetic chronic wound environment leads to the hypoxia, immunocytes damage and chronic proinflammatory state, culminating in unhealed wounds. Glucose-responsive self-healing hydrogel, which can repair self-damage spontaneously and release drugs rapidly in the hyperglycemic environment, is an important strategy for chronic diabetic wounds treatment. Herein, a glucose-responsive self-healing hydrogel was prepared based on polysaccharides: sodium alginate was oxidized into dialdehyde sodium alginate by sodium periodate; 3-aminophenylboric acid was grafted onto the chains of dialdehyde sodium alginate; phenylboric acid modified dialdehyde sodium alginate can form self-healing hydrogel (PBA-OSA-CS hydrogel) with carboxymethyl chitosan and gallic acid through dynamic imine bonds and borate ester bonds. Notably, gallic acid is not only a cross-linking agent but also an active drug for treating diabetic chronic wounds. The PBA-OSA-CS hydrogel showed three-dimensional porous structure (30‒60 μm), good injectability, self-healing properties and mechanical properties (about 22 kPa) and water absorption (about 550%). In-depth exploration revealed that PBA-OSA-CS hydrogel exhibited high sensitivity to glucose stimulation to rapidly release gallic acid. And the double cross-linked network avoided the burst disintegration of hydrogel, contributing to a continuous drug release. The release of gallic acid conformed to the Weibull distribution model (R2adj=0.997, MSC=5.021) and it obeyed the law of Fickian diffusion. Taken together, PBA-OSA-CS hydrogel with glucose response to rapidly and continuously release active drugs has potential applications in drug delivery and diabetes wound treatment.关键词：Hydrogel;Dialdehyde sodium alginate;Chitosan;Glucose responsiveness;Drug controlled release- 428
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发布时间：2023-09-25 - 摘要：Interfacial bonding and cohesive strength are the two main factors affecting the bonding strength of pressure-sensitive adhesives (PSA), so that meet both low moduli to promote surface wetting and high cohesive strength to impede crack growth is necessary. However, a positive correlation between the moduli and cohesion strength often poses a challenge in designing high-performance PSA. In this study, introducing solid-phase ionic salt (LiTFSI) into the polyelectrolyte not only effectively reduces the modulus of the PSA (7.56 MPa) and enhances the interfacial bonding, but also maintains a high strength (884 kPa), which endows a remarkable lap-shear strength of 1.09 and 1.17 MPa when bonded to metallic aluminum and polyethylene terephthalate (PET), respectively. Furthermore, the migration and/or orientation of ionic groups and free ions enhance the lap-shear strength with an efficiency of 89%. Moreover, a reversed voltage will promote ionic groups and free ions disorient and migrate in a reversed direction, resulting in lower lap-shear strength. Finally, the effect of facilitating charge collection of such PSA in triboelectric nanogenerators was demonstrated.关键词：ionogel;pressure-sensitive adhesive;electric field reinforcement;Adhesive strength
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发布时间：2023-09-25 - 摘要：Neodymium-based polybutadiene rubber (Nd-BR) with cis-1,4 content >98.0% was prepared by neodymium carboxylate-based catalyst system and Nd-BR with cis-1,4 content of 94.9% was prepared by neodymium phosphonate-based catalyst system. Commercial products with similar molecular weight (Mn) and molecular weight distribution (Mw/Mn) while different cis-1,4 contents were selected for comparison. The effects of cis-1,4 configuration on properties of Nd-BRs with similar 1,2-configuration content, molecular weight and distribution were investigated. The characteristic stress relaxation time (τ) decreased obviously when the total content of 1,4- configuration (cis-1,4 and trans -1,4) is greater than 99%, and the cis-1,4 content increases from 94.9% to 98.8%, indicating the improvement of processability. The dispersion of carbon black in rubber and bound rubber content of Nd-BR composites were improved as well. The strain-induced crystallization capability was enhanced with the increase of a small amount of cis-1,4 content, which significantly improved the tensile strength, tear strength, wear resistance, puncture resistance and crack resistance. It is remarked that the rolling resistance and wet-skid resistance were increased with ultra-high cis-1,4 content of more than 98%. Nd-BR with ultrahigh cis-1,4 content of ca. 98.5% and appropriate molecular weight distribution (ca. 2.8) possessed excellent processing properties, mechanical properties and dynamic mechanical properties, which is suitable for the high-performance tires.关键词：Butadiene;Neodymium-based cis polybutadiene rubber;Cis-1;4 configuration
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发布时间：2023-09-25 - 摘要：Isotactic polypropylene (iPP) suffers from high mold shrinkage mostly associated with the crystallization-induced volume shrinkage during the melt-processing, which inevitably leads to an inaccurate size of final products. In this work, a facile and effective strategy based on the crystallization manipulation has been reported to address this issue. To do this, β-nucleating agent (β-NA) was utilized to tailor the crystalline structure and morphology of iPP. The effect of β-form crystallization on the volume shrinkage, and linear shrinkage of injection-molded iPP products has been analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM), and scanning electron microscopy (SEM). The results show that, neat iPP can exclusively crystallize into α-form crystals upon non-isothermal melt-crystallization, whereas abundant β-form crystals are induced by adding small amounts (0.05 wt%‒0.5 wt%) of β-NA. Moreover, with the increase of β-NA content, the β-crystalline morphology is found to change from typical spherulites to unique bundle-like crystals. Very interesting, the predominant formation of β-form crystals can markedly reduce the shrinkage of the iPP products. Especially, when the fraction of β-form crystals is increased from 3.6% to 90.6%, the linear shrinkage of the products is found to decrease from 1.7% to 1.2%, while their volume shrinkage declines from 12.2% to 10.6%. This finding is in good accordance with the theoretical calculation. Further analysis indicates that such β-NA can self-organize into fibrillar crystals in iPP melts, which are prone to orientate along the flow direction and then induce the orientational crystallization of iPP chains, ultimately leading to the anisotropic shrinkage. Moreover, the shrinkage is heavily dependent on the fraction of β-form crystals, rather than the crystalline morphology. This work could provide a guideline for the development of low-shrinkage iPP materials.关键词：Polypropylene;Crystallization;Low shrinkage
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发布时间：2023-09-25 - 摘要：Poly(disulfide)s, a typical dynamic polymer, could be degraded by light, heat or chemical reductant due to its disulfide bonds in main chain. The degradation methods of poly(disulfide)s reported mainly include in the reductive or thermal degradation. However, the photodegradation of the poly(disulfide)s behavior, as well as the degrading mechanism is less involved. In this work, a systemic investigation on the photodegradation of poly(disulfide)s is presented. Under the irradiation of near UV-Vis light, the linear poly(disulfide)s are degraded into cyclic or linear poly(disulfide)s with low molecular weight. In addition, the effects of light wavelength, molecular weight and concentration of poly(disulfide)s on degradation rate were explored. Under the same conditions, poly(disulfide)s with different initial molecular weights are degraded into linear or cyclic poly(disulfide)s with the approximate molecular weight in different degradation rates; the higher the initial concentration, the higher molecular weight of poly(disulfide) is at the equilibrium state; the shorter the radiation wavelength, the longer the time is needed to reach the photodegradation equilibrium. In addition, based on the analysis of degradation products, the corresponding degradation mechanism is proposed, that is, with the irradiation of UV-Vis light, the disulfide bonds in the poly(disulfide)s homo-cleaved into corresponding sulfur free radical fragments, and different free radical fragments form linear or cyclic poly(disulfide)s with low molecular weight through intermolecular or intramolecular recombination. The photodegradation gives a new idea on the further degradation of poly(disulfide)s or other polymers with disulfide bonds.关键词：Poly(disulfide)s;Disulfide metathesis;UV-Vis light;Photodegradation
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发布时间：2023-09-25 - 摘要：Herein, after gradient organic synthesis reaction by combining with the "click" reaction (CuAAC and thiol-ene reaction), the pPFPA prepared by reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization was conducted by post-polymerization modification to produce a series of dendritic mannose glycopolymers with the adjustable rigidity and flexibility of the linking groups in the side chains. The effect of dendronized glycopolymers containing different side chain's linking groups (rigid triazole rings is prodcued by CuAAC reaction, and flexible thioether bond is produced by Thiol-ene reaction) on the recognition ability of lectin Con A was systematically studied. The isothermal titration calorimetry (ITC) test showed that compared with the rigid triazole ring, the higher the proportion of flexible link groups in the side chain of the branched glycopolymer, the stronger the binding ability of the glycopolymer with Con A. The reason could be that the flexible linking groups can provide more space on the polymer chain to combine Con A; On the other hand, the flexible linking group has a synergistic effect in the recognition of glycopolymers with Con A.关键词：Dendronized glycopolymers;Copper catalyzed azide alkyne cycloaddition reaction;Thiol-ene photochemical reaction;Lectin Con A recognition
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发布时间：2023-09-25 - 摘要：2,2'-Double(trifluoro methoxy) biphenyl-4,4'-diamine (TFMOB)/2,2'-double (three fluorinated methyl) biphenyl-4,4'-diamine (TFMB) were used as diamine monomers to synthesize poly(amide acid) precursors by co-polymerizing with two dianhydride monomers, hexafluoroisopropyl phthalic anhydride (6FDA) and 4,4'-(4,4'- isopropyldiphenoxy) bis(phthalic anhydride) (BPADA), respectively. A series of colorless transparent polyimide (CPI) films containing trifluoromethoxy (―OCF3) are obtained by thermal imidization of PAA under a certain temperature gradient. In this paper, the effects of different contents of ―OCF3 on the properties of CPI films prepared by polymerization with two different dianhydrides were investigated. The results showed that when the ratio of TFMOB to TFMB was 3:7, the properties of the prepared CPI films reach a relative balance, in the visible wavelength range of 400-760 nm, it has excellent optical transparency, transmittance of more than 80%, the 5% and 10% weight loss temperature is 532 ℃ and 550 ℃ respectively, and the residual mass percentage is higher than 50% at 800 ℃; the dielectric constant at 10 GHz is 2.647, the dielectric loss is only 0.00525; the tensile strength reaches (111.2±1.1) MPa, the elongation at break is (67.0±5.0)%; the moisture absorption is as low as 0.29%. It was proved that the introduction of ―OCF3 significantly improves the comprehensive performance of CPI film, which provides a foundation for the application of CPI film in the field of flexible photoelectric materials.关键词：Polyimide;Colorless transparent film;Excellent comprehensive performance;2;2'-Bis(trifluoromethoxy) biphenyl-4;4'-diamine
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发布时间：2023-09-25 - 摘要：The NOx/azo chromophore and the colored anthraquinone structures are important reasons for coloring PI except the well-known charge trasfer complex (CTC) effects, the polyamide acid (PAA) was synthesized from 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA)/4,4'-oxydianiline (ODA) and the polyimide film was prepared by thermal imidization. The BPDA were used as blockers to cap the residual amino of PAA, and the amino groups were prevented from producing the chromophore; the ethylene glycol was used to cap the terminal anhydride group of PAA to prevente the formation of the colored anthraquinone units, which was produced from the diamine segments substituted by the terminal anhydride groups, then the light color and high transmittance polyimide (PI) films were obtained. The test results show that the cutoff wavelength of the capped PI films shifted to the left, the color of PI films becomes lighter, the UV transmittance at 450 nm increased from 17% to 39%. The maximum transmittance was up to 99.5%, the thermal and mechanical properties of the capped polyimide films were also improved. So, the two-step end-capping method has universal applicability to improve the optical properties of polyimide films.关键词：Colorless polyimide;Charge transfer complex;End-capping;Thermal imidization
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发布时间：2023-09-25 - 摘要：Ethylene propylene diene monomer (EPDM) was filled with silica aerogel (AS), spherical silica (SS) and fumed silica (FS), which have different micropore structures and closed particle size. The mechanical properties and Mullins effect of EPDM vulcanizates before and after reinforced were analyzed. It was found that, AS with 3 times more specific surface area and pore volume than FS had a much higher reinforcement efficiency for EPDM. The tensile strength of EPDM vulcanizates reinforced with AS is 928% higher than that of pure EPDM and 4.3% higher than that of FS/EPDM. The tear strength of AS/EPDM is 411% higher than that of pure EPDM and 65.5% higher than that of FS/EPDM. SS did not improve the mechanical properties of vulcanizate. AS and FS have similar reinforcement mechanism in reinforcing EPDM. Above a critical content, Self-similar, rigid clusters formed through a diffusion-controlled cluster-cluster aggregation (CCA) with similar fractal dimension (1.75‒1.80) and EPDM chains are connected by the bound molecular segments absorbed in the pore or on the cluster surface through van der Waals force to form physical cross-linking networks. The amount of bound segments, strongly depends on the specific surface area and pore volume of filler, determines the strength of physical networks and the consequent reinforcement efficiency. Therefore, AS shows a higher efficiency in reinforcing EPDM.关键词：Silica powder;Micropore structure;Rubber reinforcement;Mechanical properties;Mullins effect
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发布时间：2023-09-25 - 摘要：Based on a strategy of combining fluorinated components with excellent stability, fluorinated natural rubber latex (FNRL) was synthesized by emulsion polymerization with NR latex (NRL) using fluorinated acrylates as monomers under mild conditions to solve the problem of poor ageing resistance caused by the unsaturated structure in natural rubber (NR). The fluorination of NRL resulted in the synthesis of FNRL with high stability and FNR latex films with excellent UV and ozone resistance. The results show that FNRL has high stability and its mechanical stability and thermal stability are qualified, which is slightly better than that of the commercial concentrated latex. FNR vulcanized (FNR-V) latex film has better UV and ozone resistance than those of NR vulcanized (NR-V) latex film. After accelerated UV aging test, the crack width of the FNR-V latex film is only 1/3 of that of the NR-V latex film. After ozone aging test, the surface cracking of FNR-V latex films is evaluated at level 1a, while that of NR-V is level 4c. This study provides a feasible way of fluorinated NRL, whose vulcanized latex film has significant improvements in UV and ozone resistance compared to NR latex film, and FNR-V latex film is expected to be widely used under more severe climatic conditions (UV and ozone).关键词：Fluorinated NR latex;Stability;UV resistance;Ozone resistance
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发布时间：2023-09-25
Research Article
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