最新刊期
卷 53 ， 期 3 ， 2022
- 摘要：Structural color plays an important role in nature and is widely distributed in insect exoskeletons, bird feathers and plant fruits. Cellulose is abundant in nature and has a huge increment annually and naturally arranges into regular structures to form a structural color in some plants. The cellulose nanocrystals (CNCs) papered by sulfuric acid hydrolysis will self-assemble to form left-handed chiral nematic structures at critical concentration in water. This chiral nematic structure can be maintained in the photonic crystal iridescent film after water volatilities, like those plants, which has dual properties of extremely strong chirality and the photonic crystals. The periodic layered structure in the film has complex interference and diffraction with the light and shows complex iridescence. These artificially prepared structural colors can be tuned by changing the source of raw materials, adjusting the assembly process, and adding other substances. The preparation process and self-assembly process of CNCs are the most commonly methods to tune structural color. Because it can be flexibly adjusted, for example, tuning the structure by changing the morphology of CNCs, the hydrolysis conditions or ultrasound, additives, time and temperature during the self-assembly process. Due to its unique optical properties, CNCS chiral composites prepared by combining CNCs with other materials to improve mechanical properties have broad application prospects in sensor and anti-counterfeiting. In the existing reports, humidity response, temperature response, organic solvent and other gas response, mechanical force response and furthermore, multiple responses have been realized. And in recent years, CNCs chiral optical devices which rely on chiral nematic phase have gradually become another important research direction. In this view, the research progress of structure color control, stimuli-response, pattern display and circularly polarized optics of CNCS composites is discussed.关键词：Cellulose nanocrystals;Structural color;chiral nematic;Self-assemble;circular polarization
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发布时间：2024-10-08
Review
- 摘要：Phospholipidated starch was synthesized according to the reaction between hydroxyl of starch and anhydride prepared by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and maleic anhydride (MA), which was characterized by Fourier infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), and X-ray photoelectron spectrometry (XPS). Melt-blended with ammonium polyphosphate (APP), the phosphorous-containing starch (DOPOMASt) was used in intumescent flame retardancy of poly(lactic acid) (PLA) as carbon source. The thermal stability and flame retardancy of PLA composites were measured by vertical burning test (UL-94), limiting oxygen index (LOI) and thermogravimetric analysis (TGA). Dispersion of flame retardants in PLA and morphology of char residues after UL-94 test were observed by scanning electron microscopy (SEM). The gases released during thermal degradation of PLA composites were analyzed by TG-IR. The results showed that the uniform distribution of DOPOMASt and APP in PLA matrix was observed. When the mass ratio of DOPOMASt/APP is equal to 1/1, the LOI value of 26.0% and a UL-94 V0 rating were achieved with 10% total flame retardants. Synergistic effect of DOPOMASt and APP resulted in a compact cross-linked char layer and reduction of the retardant-induced smoke release.关键词：Poly(lactic acid);Phospholipidated starch;Ammonium polyphosphate;Flame retardant
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发布时间：2024-10-08 - 摘要：Repeatedly chemically recyclable and biodegradable poly(p-dioxanone) (PPDO) has some problems, such as rapidly hydrolytic degradation, which is not beneficial to its storage and practical application. Herein, poly(p-dioxanone-co-n-alkyl substituents δ-lactone) (PDRVL) copolymers with side chains of different lenghs were synthesized by bulk copolymerization of p-dioxanone with n-alkyl substituents δ-lactone (RVL) under DPP catalysis. The thermal, crystalline and mechanical properties of the copolymers were studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), wide angle X-ray diffraction analysis (WXRD) and tensile test. The results show that initial decomposition temperature and maximum decomposition temperature of the copolymers are about 250 and 390 °C, much higher than their melting point (96.2-99.6°C), indicating that the copolymers can meet the requirements of processing and be used as thermoplastic polymers. The copolymers are semi-crystalline polymers, and their crystallinity (Dc) obtained from WXRD is in the range of 34%-38% and decreases with the increasing chain lengh of alkyl substituents of the comonomer. The mechanical properties of the copolymer were controlled by changing the structure of the comonomer. As the chain lengh of alkyl substituents of the comonomer increased from 3 to 7, the elastic modulus of the copolymer decreased from 483.8 MPa to 356.0 MPa, the yield strength decreased from 24.3 MPa to 21.6 MPa, and the elongation at break remained in the range of 212.7%-235.0%.Water contact angle (WCA) and water absorption test show that the introduction of hydrophobic RVL monomer weakened the hydrophilicity of PPDO, and the water absorption of the copolymer decreased with the number of carbon atoms in hydrophobic alkyl substituents of RVL. When the number of carbon atoms in the alkyl substituents was over 3, the copolymer was hydrophobic. The hydrolytic degradation of the copolymers was studied. By testing mass retention rate, the characteristic viscosity retention rate, and the sample surface microstructure during the degradation process, it can be concluded that different comonomer structures exert no significant effect on the hydrolytic degradation of copolymers. However, compared with the PPDO homopolymer, the PPDO-based copolymers containing hydrophobic RVL with substituted alkyl chain possessed the significantly delayed hydrolytic degradation.关键词：Poly(p-dioxanone);n-Alkyl substituents δ-Lactone;Ring-opening polymerization;Copolymer;hydrolytic degradation
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发布时间：2024-10-08 - 摘要：In the producing process of wet-process separator, the heat setting process is different from the conventional one, because in addition to the high temperature treatment, the separator also needs to be stretched and retracted. That is, the coupling effect of stretching external field and temperature field act on the wet separator during the heat setting process. In this study, by designing different draw ratios and retraction ratios, the influence of the external stretching field (draw ratio, retraction ratio) on the microstructure and macro thermal shrinkage properties of the separators during the heat setting process is studied. It was found that a small draw ratio (≤1.3) only acts on the amorphous region of polyethylene. As the draw ratio increases, the polyethylene crystals begin to be stretched and destroyed, resulting in the decrease of crystallinity and crystal size. At the same time, increasing draw ratio could enlarge the pore diameter of the wet separator. While the pore diameter of the separator also increases with the retraction ratio, indicating that the fiber fusion and pore enlargement occur during the retraction process. In addition, the increase of the draw ratio and the retraction ratio is beneficial to the release of the internal stress in separator, so that the TD thermal shrinkage of the separator is significantly reduced.关键词：Wet-Process Separator;Internal Stress;Heat Setting;Pore Size;Heat Shrinkage
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发布时间：2024-10-08 - 摘要：A series of isotactic polybutene-1 (PB-1) in phase Ⅱ obtained via isothermal crystallization at 50 ℃ were treated with different solvent vapors. Wide-anlge X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) techniques were used to evaluate such samples before and after treatment. Meanwhile, in situ XRD was used to study the phase transition process of PB-1 annealed in different solvent vapors. Solvents, except water and alcohol solvents, such as n-hexane, chloroform, 1,2-dichloroethane, benzene, toluene, xylene, chlorobenzene, ethyl acetate, tetrahydrofuran, acetone have obvious accelerating effect on the phase transition process, which can shorten the phase transition time from more than 4-5 days under normal conditions to tens of minutes. Through in situ XRD characterization, it was found that during the solvent annealing process, the crystal form Ⅱ of PB-1 disappeared while the crystal form I was formed. The entrance of solvents, which promotes the crystal form transformation, can be divided into two steps: adsorption and diffusion. Adsorption is affected by solubility parameters and polarity, while diffusion mainly depended on the geometric size of solvent molecules: a small size in any direction will lead to a faster spread and larger promotion effect. Through this research, we found that n-hexane or petroleum ether is an efficient and low-toxic solvent that accelerates the Ⅱ-I phase transition of PB-1, and has good application prospects.关键词：Isotactic polybutene-1;Crystal transformation;Solvent vapor annealing;X-ray diffraction
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发布时间：2024-10-08 - 摘要：Poly(aryl ether ketone)s are high performance engineering plastics with excellent comprehensive performance. They are usually prepared by solution polycondensation at high temperature with bisphenol monomers and dihalogen monomer. Polycondensation at high temperature makes it difficult to prepare and raises production costs. As a result, preparation of poly(aryl ether ketone)s at low temperature is significant in scientific research and industrial production. On the other hand, introduction of fluorine atoms into poly(aryl ether ketone)s with phthalazinone can optimize comprehensive properties. Here, fluorine atoms are introduced in dihalogen monomers to prepare fluorine substituted poly(aryl ether ketone)s at low temperature. Long-chain dihalogenated monomers are obtained by Friedel-Crafts acylation reaction with pentafluorobenzoic acid instead of p-fluorobenzoic acid. Fluorine substituted long-chain dihalogenated monomers are used in preparation of poly(aryl ether ketone)s with phthalazinone at low temperature. Fluorine atoms were introduced into main chain of poly(aryl ether ketone)s containing phthalazinone. Polyfluorosubstituted dihalogenated monomers have multiple reaction sites. Low temperature reaction and two-step feeding polymerization route ensure that solution polycondensation reaction is carried out at certain position of polyfluorosubstituted dihalogenated monomers and that fluorine substituted poly(aryl ether ketone)s with phthalazinone are linear polymers. The introduction of fluorine atoms has an impact on synthetic route, molecular structure, number average molecular weight, thermal properties and sequence structure of poly(aryl ether ketone)s with phthalazinone. Two kinds of fluorine substituted poly(aryl ether ketone)s with phthalazinone synthesised with long-chain dihalogenated monomers are amorphous polymers. With the introduction of fluorine atoms, glass transition temperatures of the corresponding poly(aryl ether ketone)s with phthalazinone are improved; while number-average molecule weight and thermal decomposition temperature of fluorine substituted poly(aryl ether ketone)s with phthalazinone are reduced, due to the low-temperature reaction. Otherwise, fluorine substituted poly(aryl ether ketone)s with phthalazinone have potential for further post functionalization. It's expected that this study could provide reference for other researchers.关键词：Phthalazinone;Poly(aryl ether ketone);Fluoro-substitution;Sequence structure
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发布时间：2024-10-08 - 摘要：Flexible conducting polymers have potential applications in future wearable or portable electronics. However, conducting polymers with rigid structure were difficultly prepared into robust flexible films, especially, their electrochemical instability is a critical defect. Therefore, the preparation of high-quality flexible conducting polymer films is both meaningful and challenging. Here, a self-supporting flexible poly(5-indolylboronic acid) (PInBA) film with an electrical conductivity of 9×10-4 S·cm-1 is facilely prepared by direct anodic oxidation of 5-indolylboronic acid in the mixed system of 80% boron trifluoride diethyl etherate and acetonitrile. The initial oxidation potential of 5-indolylboronic acid in 80% boron trifluoride diethyl etherate-acetonitrile solution is about 0.80 V versus Ag/AgCl, lower than that determined in acetonitrile system (0.93 V versus Ag/AgCl). The structure, electrochemical performance and thermal stability of PInBA film are investigated by Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, cyclic voltammetry and thermogravimetric analysis. The results of FTIR spectra confirm that the polymerization sites of 5-indolylboronic acid are at the C2 and C3 positions. The UV-Vis spectrum proves that the band gap of PInBA is 2.48 eV. And as-prepared PInBA film has excellent electrochemical performance, high thermal stability and good mechanical properties. These results indicate that the PInBA film is a promising electrode material for flexible electronics such as electrochemical sensors, supercapacitors and thermoelectrics.关键词：Conducting polymer;5-Indolylboronic acid;Electropolymerization;Flexible film
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发布时间：2024-10-08 - 摘要：In this work, a novel type of polysuccinimide (PSI) derivative with dopamine and zwitterionic sulfobetaine groups in the side chain was designed and synthesized via nucleophilic ring-opening reaction on polysuccinimide. Then, a biomimetic superhydrophilic coating (PSI-DA-ZW/glass) was prepared through the oxidative self-polymerization and deposition of the pendant catechol anchor group in PSI-DA-ZW on the surface of glass. The micro-chemical structure, wettability and transmittance of the functional coatings were characterized by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), contact angle measuring instrument, and UV-visible spectroscopy (UV-Vis), respectively. The research results showed that the zwitterionic group was successfully introduced to the surface of the PSI-DA-ZW/glass sample. Compared with the original surfaces, the obtained biomimetic functional surface had self-assembly into nanoscale microstructures, with a water contact angle (WCA) close to 0° and an underwater-oil contact angle (UWOCA) close to 180°, presenting excellent superhydrophilic and underwater oil-repellent properties. Meanwhile, the functional surface had a light transmittance of 90.4% at 550 nm, showing good antireflection effect compared with that of the blank glass. Moreover, the bacterial adhesion experiments demonstrated that PSI-DA-ZW/glass surface exhibited obvious anti-adhesion properties for S. aureus and E. coli. The simple and effective method for preparing biomimetic functional surface proposed in this study is suitable for different substrates and thus had potential application in the fields of sanitary materials, biomedical coatings, oil-water separation, antifouling coatings and so on.关键词：Superhydrophilic surface;Zwitterionic;Dopamine;Polysuccinimide derivatives;Biomimetic modification
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发布时间：2024-10-08
Research Article
- 摘要：The performance and functionality of polymeric materials depend strongly on the multiscale structures. While the chemical structure of a polymer determines its basic property and functionality, the structures at different scales in solid state can change the performance and even enable the polymer special functions. For example, the modulus of highly oriented ultrahigh molecular weight polyethylene is three orders of magnitude higher than that of its non-oriented counterpart. For the polymorphic poly(vinylidene fluoride), special piezoelectric and ferroelectric functions can be endowed by crystallizing it in the β and γ crystal modifications. Therefore, it is of great significance to disclose the structure formation mechanism of polymers at all levels, to realize the precise regulation of them and to correlate them with their performance. This leads to the study of polymer structure at varied scales and the related structure-property relationship a very important research field of polymer physics. Here in this paper, we will focus on the application of transmission electron microscopy in the study of different hierarch structures of polymers, including a brief introduction of the working principle of transmission electron microscopy, special techniques used for sample preparation and for instrument operation to get high-quality experimental data, analysis of the results and correlation of them to different structures.关键词：Polymer;Transmission electron microscopy;Sample preparation;Instrument operation;Structure explanation
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发布时间：2024-10-08
Review (Special Topic: Techniques of Polymer Characterization)
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