最新刊期
卷 52 ， 期 12 ， 2021
- 摘要：Polymer processing determines the final structural performance of plastic products. Polymer rheology is one of the most important theoretical basis, and rheometer is the key instrument to study polymer rheology. However, most of the existing rheometers are based on simplified flow models, which are inconsistent with the practical conditions, and difficult to effectively reveal the rheological behavior of polymers under the complex stress/temperature fields in practical processing. Based on self-developed rotation extrusion processing technology and equipment, we have developed a novel rotation-extrusion rheometer, which can realize different combinations of extrusion/rotation and double cooling of the inner and outer walls of the tube; implement and control various motion modes, stress and temperature fields during rotation extrusion; and achieve real-time detection, display and recording of data about extrusion/rotation speed, stress, temperature field. The rotation-extrusion rheometer can be used not only to study the rheological behavior of polymer processing under complex conditions in practical processing, but also to prepare high performance multifunctional polymer tubes. The structural features, principles and application of the novel extrusion-rheometer in rheological testing and preparation of polymer tube are reviewed.关键词：Rotation-extrusion rheometer;Structure and principle;Multi-motion mode rheological test;Multifunctional polymer tube
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发布时间：2023-05-22
Feature Article
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Antibacterial Micelles Self-assembled from Copolypeptides through a One-step Acidification Process 增强出版
摘要：We propose a one-step acidification method for facile preparation of antibacterial micelles. The random copolypeptide TPE-P(Lys28-stat-BLG16) was obtained by selective deprotection of the trifluoroacetyl groups from a TPE-P[Lys(Tfa)28-stat-BLG16] precursor. This initial random copolypeptide was synthesized by ring-opening copolymerization of Nε-trifluoroacetyl-l-lysine N-carboxyanhydride [Lys(Tfa) NCA] and γ-benzyl-l-glutamate N-carboxyanhydride (BLG NCA) using 4-(1,2,2-triphenylvinyl)aniline (TPE-NH2) as initiator. After polymerization and deprotection, polymer micelles were formed by acidification of the crude aqueous TPE-P(Lys28-stat-BLG16) reaction mixture. Thus, this method is called a "one-step acidification process". The obtained micelles should have good antibacterial properties, given that this random copolypeptide comprises a large number of aromatic and amino groups. The antibacterial properties of these micelles were evaluated using the broth microdilution method and the plate paint method, to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). These tests showed that these polymer micelles have indeed antibacterial properties: the determined MICs for E. coli and S. aureus were 256 and 64 μg/mL; the determined MBCs for these bacteria were 400 and 100 μg/mL, respectively. Interestingly, these antibacterial micelles produce bright blue fluorescence light under UV exposure, owing to the aggregation-induced emission (AIE) effect of the TPE end groups. Herein, this property was used to optically explore the antibacterial mechanism of these polymer micelles. This approach indicated that these polymer micelles kill bacteria by piercing their membrane via a physically damaging process.关键词：polypeptides;one-step acidification;Micelles;Self-assembly;Antibacterial- 593
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发布时间：2023-05-22 - 摘要：In recent years, smart materials have attracted much attention. The active switch of smart materials can be turned on or off reversibly in response to different external stimuli. Inspired by previous studies, we have prepared a photo-responsive smart wetting material with spiropyran as the active switch group. The photosensitive monomer 3-(3',3'-dimethyl-6-nitrospiro-(chromene-2,2'-indolin)-1'-yl) propyl methacrylate (SPMA) was grafted on the surface of polydimethylsiloxane (PDMS) by free radical copolymerization to prepare a photo-responsive film named SPMA-g-PDMS. The film is sensitive to ambient light, and it is colorless and transparent under visible light, while after being excited by 365 nm ultraviolet light for 15 s, it immediately turn purplish, accompanied by the change of polarity, resulting in the wettability transition of the film. When SPMA-g-PDMS is exposed to visible light or darkness, the wettability of the film can be restored to its initial state. The difference of contact angle before and after ultraviolet irradiation can reach 38.5°. This remarkable performance of reversible switchable wetting gives SPMA-g-PDMS potential application value in the fields of biomedical materials, cell culture, non-enzymatic desorption, smart window coating and so on. In addition, after several alternating UV-visible light cycles, SPMA-g-PDMS still possesses good photo response and reversible wetting performances.关键词：Light response;Spiropyran;reversible wettability;Polydimethylsiloxane
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发布时间：2023-05-22 - 摘要：A novel organic carbazolyl-quinoline derivative with D-π-A structure, 9-[4-(quinoline-8-yl)phenyl]-9H-carbazole (CPBA-Qx), was designed and synthesized, in which carbazole was used as electron donor (D), quinoline as the electron acceptor (A) and phenyl spacer as π-bridge. Based on the designed blue-emitting small-molecule CPBA-Qx, a blue-emitting polymer, poly[3-phenyl-9-(4-(quinoline-8-yl)phenyl)-9H-carbazole] (poly(CPBAQx-P)), was designed and synthesized by Suzuki coupling copolymerization with donor as the main chain and acceptor as the side chain according to the molecular designing strategy of TADF polymer. Aggregation-induced enhanced emission (AIEE) performances of CPBA-Qx and poly(CPBAQx-P) were examined by studying the PL emission behaviour of their diluted mixtures in THF/H2O with different water fractions (fw). Compared with pure solution, the study showed that the PL intensity and quantum yield (ΦPL) of CPBA-Qx and poly(CPBAQx-P) are significantly enhanced by 2‒10 times in the aggregate state, exhibiting typical AIEE characteristics. Meanwhile, both of them exhibited obviously delayed fluorescence with the lifetime of 1.25 and 1.09 μs, accompanied by prompt fluorescence of 3.78 and 3.41 ns. For instance, the temperature-dependent transient photoluminescence spectra measured for CPBA-Qx and poly(CPBAQx-P) displayed enhanced delayed fluorescence upon the temperature rising from 100 K to 300 K, indicative of their TADF nature. The excellent TADF characteristics were closely related to extremely narrow singlet-triplet state energy splitting (ΔEST, CPBA-Qx 0.11 eV and poly(CPBAQx-P) 0.16 eV). As a consequence, using CPBA-Qx and (poly(CPBAQx-P) as emitters, the turn-on voltage (Von) and threshold voltage (Vth) of solution-processable nondoped OLEDs were 3.26/12 V and 2.91/11 V, respectively. The maximum external quantum efficiency (EQEmax) and Commission Internationale De L'Eclairage (CIE) coordinates were 5.24% and (0.19, 0.12), 8.39% and (0.17, 0.10), respectively. Moreover, the non-doped OLED based on poly(CPBAQx-P) can retain high EL efficiency (EQE=7.42%) at 1000 cd·m-2, with small efficiency roll-off, a narrow full width at half maximum (FWHM=59 nm) and CIE y≤0.1. To sum up, poly(CPBAQx-P) as an emitter has great potential in solution-processed non-doped OLEDs, which lays experimental foundation for the application of AIEE-TADF polymer in OLEDs.关键词：Thermally activated delayed fluorescence;Aggregation induced enhanced emission;Blue emission;Carbazolyl quinoline derivatives;Organic light-emitting diodes;Non-doped devices
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发布时间：2023-05-22 - 摘要：Our recent work showed that amphiphilic bottlebrush block copolymer (polynorbornene-graft-polystyrene)-block-(polynorbornene-graft-poly(ethylene oxide)) (PS-b-PEO) could induce organized spontaneous emulsification, yielding structural colored porous microspheres templated by ordered water-in-oil-in-water (W/O/W) double emulsion droplets. Herein, we demonstrate the design and synthesis of a series of triblock copolymers with a poly(tert-butylacrylate) (PtBA) block between PS and PEO blocks, and disclose the influence of the middle block on interfacial self-assembly. It turned out that the transition layer at W/O interface becomes thicker in the presence of PtBA block, leading to great influence on packing parameters of the bottlebrush amphiphiles. Even though decreased ordering of nanopore arrays is observed relative to that of diblock copolymers, the middle block enables the wide tuning of reflection across the whole visible spectrum (471-717 nm) simply through variation of droplet evaporation time. Moreover, stimuli-responsive structural colored microspheres are obtained via hydrolysis of PtBA to poly(acrylic acid) (PAA) which can react with organic bases and form organic salts, leading to enhanced hydrophilicity of the microspheres, swelling of the photonic structure, and red-shift of structural color. A large increase of reflection maximum of up to 50 nm is achieved in the presence of arginine at a low concentration of 10-3 mol/L. Such a color change can be completed within 4 min, providing an effective method for fast and sensitive detection. This work not only provides useful fundamental knowledge regarding the interfacial self-assembly of triblock copolymers, but also demonstrates an effective strategy for making stimuli-responsive photonic structures.关键词：Block copolymer;Interfacial self-assembly;Structural color;Stimuli-responsive behaviors
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发布时间：2023-05-22 - 摘要：α-Diimine nickel and palladium catalysts catalyze olefins polymerization to form branched products because of unique chain walking characteristics. Design and optimization of catalyst ligand structure can control its catalytic properties and chain walking process, thereby developing high-performance polyolefins. In this paper, new α-diimine nickel and palladium complexes with a rigid camphyl backbone were designed and synthesized for oligomerization of decene mixture. X-ray single crystal diffraction patterns of nickel (Ni-1) and palladium (Pd-1) complexes clearly proved molecular structure of nickel and palladium complexes. The buried volume of nickel and palladium complexes calculated by single crystal structure data supported the bulky steric effect of the camphyl backbone. The influence of metal center, solvent, temperature and Al/Ni ratio on oligomerization of decene mixture were studied in detail. Palladium-based catalyst was nearly inactive but nickel-based catalyst showed good activity toward oligomerization of decene mixture. In combination with isomerization of nonterminal olefins, linear components of decene mixture were nearly converted to oligomers. The resultant polyolefins were highly branched (branching degree >120/1000C) and had low molecular weight (3100‒4540 g/mol). The lubricant properties of the resultant oil products were further evaluated according to Chinese national standard. These polyolefin oils had excellent properties of viscosity index higher than 170 and pour point lower than -30°C, showing a good potential in the field of polyolefin lubricant base oil.关键词：Nickel and palladium catalysts;Olefin;Oligomerization;Branching
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发布时间：2023-05-22 - 摘要：A diblock copolymer containing polydimethylsiloxane and an azobenzene-based liquid crystalline polymer, PDMS-b-PAz, was synthesized by atom transfer radical polymerization (ATRP). The volume fraction of PDMS was 27%. Atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GI-SAXS) were used to investigate the morphologies of thin films with different thicknesses after thermal annealing and unpolarized light orientation. The results show that the disordered cylindrical structure is formed in thinner films during thermal annealing. However, when the film thickness is increased to 319 nm, a coexistence of in-plane and out-of-plane arranged PDMS nanocylinders were observed. Even when the film thickness is increased to 406 nm, this coexistent state still remains. The microphase-separated structure perpendicular to the substrate can be obtained even for the thin film with a thickness of only 55 nm when being aligned with unpolarized light, and this structure is maintained when the film thickness is increased to 406 nm. This is the first time that the perpendicular orientation of PDMS nanocylinders in block copolymer films is obtained by the alignment of unpolarized light. This orientation method will benefit the application of PDMS-containing block copolymer films in nanotemplates and other fields.关键词：Block copolymer;Azobenzene-based liquid crystalline polymer;Polydimethylsiloxane;Unpolarized light orientation
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发布时间：2023-05-22 - 摘要：Slippery liquid-infused porous surface (SLIPS) is an emerging low-adhesion material that has found wide uses in anti-icing and anti-fouling. However, the poor adhesion of SLIPSs by top-down methods restricts the practical applications of SLIPSs. In the current research, we fabricated an epoxy-based SLIPS with excellent liquid-repellent and anti-icing properties. The porous epoxy resin substrate was primarily constructed by breath figure and then modified with polydimethylsiloxane (PDMS). Silicone oil was infiltrated within the substrate, serving as the lubricant layer. The hygroscopic polyamine cross-linker plays a crucial role in inducing water droplet nucleation. The surface pore size of the epoxy substrate grows from 4.09 μm to 5.09 μm while the porosity increases from 4.73% to 46.67% when the environmental humidity is elevated from (65±5)% to (95±5)%. The porous epoxy coatings attach robustly to a variety of metal substrates with an adhesion strength of around 2.2 MPa. After grafting PDMS, the pores were filled with the polymer, which could reserve silicone oil through polymer swelling and capillary sorption. The SLIPS prepared based on the epoxy substrate exhibits an extremely low water sliding angle of 2°, as well as excellent repellence to a variety of liquids including coffee, Chinese ink, milk and even high-viscous honey. On the other hand, the dynamic lubricant layer endows the coating with excellent anti-icing property owing to its low freezing temperature. The coating performs a much longer delay in freezing time (632 s) than those of the glass (21 s) and epoxy coating (94 s), as well as ultralow ice adhesion strength of 1.75 kPa in contrast to the glass substrate (166.9 kPa) and epoxy coating (50.7 kPa), indicating excellent anti-icing performance. The ice adhesion strength on our SLIPS is much smaller than those on commercial and some reported anti-icing coatings. Moreover, no obvious increase in ice adhesion strength can be observed after 20 times tests, displaying outstanding long-term anti-icing property.关键词：Breath figure;Epoxy resin;slippery liquid infused porous surface;Anti-icing
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发布时间：2023-05-22
Research Article
- 摘要：The synchrotron radiation hard X-ray scattering technology is a powerful tool to characterize the crystalline and other ordered structures of polymer materials. For the high temporal and spatial resolutions, modern synchrotron radiation light sources own the powerful capability of real-time, in situ, dynamic and non-destructive characterization. Thus, it gives the synchrotron radiation hard X-ray scattering technology a huge advantage for the study of structural evolutions far away from the equilibrium during the processing and service of polymer materials. To give full play to this advantage, the reasonable design of in situ instruments and the control of sample environments during the in situ synchrotron radiation experiments are critical. In this review, we first introduce the whole procedures of in situ experiments through a specific research case, including the design of in situ synchrotron radiation experiments, the development of in situ instruments, operation skills and data processing. We hope that the detailed introduction can help the audiences establish a fundamental cognition of the in situ synchrotron radiation experiments. Finally, we select several representative polymer material systems and the corresponding sample environments, and briefly overview the applications of the synchrotron radiation hard X-ray scattering technology in studying the multi-scale structural evolutions of these polymers under complex processing fields. We believe that these applications would inspire the audiences to think and deepen their understanding on the synchrotron radiation in situ experiments by using in situ instruments. Undoubtedly, it is beneficial to further expand the applications of the synchrotron radiation hard X-ray scattering technology on the characterization of polymer materials.关键词：Synchrotron radiation hard X-ray scattering technology;In situ instruments;Processing of polymer materials;Multi-scale structural evolutions
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发布时间：2023-05-22
Review (Special Topic: Techniques of Polymer Characterization)
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