最新刊期
卷 54 ， 期 7 ， 2023
- 摘要：Minority groups are non-repeat units with low-volume fractions that inevitably exist in polymers. Generally, these minority groups are easily surrounded by the repeating units and randomly dispersed in the condensed state, accompanied by an increment in entropy. In this feature article, we focus on strategies to regulate the geometric distribution of supramolecular forces in polymers to achieve anti-entropy aggregation (AEA) of minority groups. It mainly includes the driving force of polymer crystallization, the supramolecular interaction of minority groups in amorphous polymers, the nanoconfined effect of microphase separation in block copolymers, and the synergetic effect between supramolecular interaction and nanoconfined interaction. We further present several analytic techniques to characterize the anti-entropy aggregation of minority groups, such as X-ray techniques, fluorescence spectroscopy, infrared spectroscopy, zeta potential, and rheology. Further, the applications of AEA materials in the fields of fluorescence probes, self-healing, ion transporting regulation, and osmotic energy conversion are comprehensively discussed. Finally, we summarize the advantages of AEA materials toward traditional functional polymers and prospect the fabrication of the complex inspired systems with the AEA strategy.关键词：Anti-entropy aggregation;Minority groups;Functional polymers
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发布时间：2023-06-21 - 摘要：Due to the similarity to extracellular matrix, hydrogels have been widely used in biomedical field such as drug delivery, tissue engineering and in vitro cell culture. Deoxyribonucleic acid (DNA) is known for the clear chemical composition, designable sequence and unique structural rigidity, which makes DNA an ideal material for construction of hydrogels. Based on our research, this review summarizes recent developments in DNA supramolecular hydrogels. Firstly, the construction strategies including the pure and hybrid DNA supramolecular hydrogels are introduced. While the construction of pure DNA supramolecular hydrogels is mainly based on base pairing or physical entanglement, covalent or non-covalent doping is also demonstrated to play important roles in preparing the hybrid hydrogels. Then, the physical properties of the DNA supramolecular hydrogels are discussed, such as the excellent permeability, tunable mechanical strength and dynamic properties. Next, the functionalization strategies are also summarized, including sequence design, chemical modification and network interpenetration. Furthermore, the applications of DNA supramolecular hydrogels in biomedicine are introduced, focusing on three-dimensional cell culture and printing, tissue engineering, immunotherapy and drug delivery. Finally, some challenges and future perspectives in the development of DNA supramolecular hydrogels are discussed. It is expected that with the flourishing development, DNA supramolecular hydrogels will have more applications.关键词：DNA supramolecular hydrogel;Functionalization;Biomedical application
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发布时间：2023-06-21
Feature Article
- 摘要：Recently, intrinsic self-healing polysiloxane materials owing to the excellent performances of silicone materials like resistance to high/low temperature, electrical insulation, hydrophobicity and biocompatibility, and novel self-healing ability to damages, have shown great potential in smart coatings, sensors, flexible devices and other fields. Intrinsic self-healing polysiloxane materials are mainly constructed by introducing dynamic non-covalent bonds (hydrogen bond, metal-ligand coordination interaction, ionic bond, etc.) or/and dynamic covalent bonds (Diels-Alder bond, imine bond, boronic ester bond, siloxane bond, disulphide bond, etc.) into their crosslinked networks. These dynamic bonds can be reversibly dissociated and recombined under moderate external stimuli, which thus enable the polymers to repair damage and restore functions. To date, dozens of self-healing mechanisms or systems for polysiloxane materials have been reported, but there is still a great challenge between excellent self-healing ability and high mechanical strengths. To address this fundamental issue, the crosslinked network of polysiloxane materials is converted from single dynamic bond to multiple dynamic bonds. The synergetic combination of dynamic covalent bond and non-covalent bond plays an important role in the efficient regulation of mechanical performances and self-healing capacities. Besides, the orientation, crystallization or phase separation of polymer chains is also considered as an effective way to improve the comprehensive properties of self-healing polysiloxane materials, because it can compensate for the reduction of mechanical properties to a certain extent. Moreover, the compositing polysiloxane materials with diverse nano-fillers grafted with dynamic bonds not only improve their comprehensive performances but also give new functions such as electric conduction, sensing, heat conduction. In view of this, this paper will review the network structure design, self-healing mechanism, property regulation and potential applications of intrinsic self-healing polysiloxane materials, based on their structural differences of dynamic bonds and dynamic crosslinked networks. Finally, an outlook on the future development of intrinsic self-healing polysiloxane materials is prospected.关键词：Polysiloxane materials;Self-healing;Dynamic crosslinked network;Dynamic noncovalent bonds;Dynamic covalent bonds
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发布时间：2023-06-21
Review
- 摘要：Vascular grafts are prone to cause risks of endothelial damage and microbial infection during implantation, so there is an urgent need to find multifunctional biomaterials with endothelializable and antibacterial functions to reduce these risks. Host defense peptides (HDPs) have broad-spectrum antimicrobial activity and are widely used to inhibit microbial infections. However, the application of these peptides is limited due to their low stability, expensive and time-consuming synthesis. Therefore, in order to meet the multifunctional requirements of vascular grafts and address these limitations, endothelializable β-peptide polymer NM40CH60 was used as HDPs mimics for antibacterial functional studies in this work. β-Peptide polymer NM40CH60 was grafted to the surface of thermoplastic polyurethane (TPU), commonly used in artificial vascular grafts, via a process of O2 plasma activation followed by brominated modification. The effective functionalization of TPU surface was confirmed by ellipsometry, X-ray photoelectron spectroscopy and water contact angle characterization. Antibacterial studies showed that NM40CH60-modified TPU surface exhibited broad-spectrum antibacterial activity against multi-drug resistant Gram-positive and Gram-negative bacteria, as well as efficient contact-killing ability. Antimicrobial mechanism study indicated that NM40CH60-modified TPU surface killed bacteria by interacting with bacterial membrane. Meanwhile, the functionalized TPU surface displayed excellent blood compatibility. In addition, β-peptide polymer NM40CH60-modified TPU surface maintained superior endothelial-selective cell adhesion, which can effectively reduce the risk of microbial infection and endothelial damage of vascular grafts, implying great potential in the treatment of cardiovascular disease.关键词：β-Peptide polymer;Host defense peptide;Antibacterial;Endothelialization
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发布时间：2023-06-21 - 摘要：Using 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid as the cellulose solvent and water as the coagulation bath, regenerated cellulose aerogels and regenerated cellulose films were obtained at different coagulation bath temperatures by regulating the coagulation temperature, and the relationship between the microstructure and properties of regenerated cellulose aerogels and regenerated cellulose membranes was investigated. The results show that the coagulation bath temperature has a significant effect on the microstructure of regenerated cellulose aerogels and regenerated cellulose films, which in turn affects the optical and mechanical properties of regenerated cellulose aerogel films and regenerated cellulose films. When the coagulation bath temperature is low, the diffusion rate of ionic liquid into the coagulation bath is slow, the regeneration rate of cellulose solution is slow, and the structural difference between the surface and the interior of the cellulose hydrogel is smaller and denser. When the coagulation bath temperature is high, the diffusion rate of ionic liquid into the coagulation bath is faster, the regeneration rate of cellulose solution is faster, and the structural difference between the surface and the interior of the cellulose hydrogel is larger and looser. With the increase of the coagulation bath temperature, the pore size of the cellulose aerogel increases, the porosity increases, the specific surface area decreases, and more importantly, the surface pore size is obviously larger than the internal pore size, and this difference increases significantly with the increase of the coagulation bath temperature. The changes in the microstructure of the cellulose aerogel resulted in the decrease of its mechanical strength, Young's modulus, elongation at break and light transmission from 3.1 MPa, 41.5 MPa, 24.7% and 88.82% to 0.2 MPa, 7.3 MPa, 4.6% and 0.07%, respectively. However, with the increase of coagulation bath temperature, the crystallinity of regenerated cellulose film decreases and the surface roughness increases, its mechanical strength, Young's modulus and elongation at break decreased from 162.3 MPa, 5389.8 MPa and 22.6% to 43.1 MPa, 3923.4 MPa and 1.4%, respectively, while the light transmission was higher than 80% and the haze increased significantly up to 40%. Thus, the relationship between the coagulation bath temperature and the performance of the regenerated cellulose material was established, which is a guideline for the industrial production of regenerated cellulose material with ionic liquid as the solvent.关键词：Cellulose;Ionic liquids;Gel;Film;Structure and performance
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发布时间：2023-06-21 - 摘要：The self-healing properties of rubber products can be given by the introduction of dynamic crosslinking bonds. In this work, carboxylated cellulose nanocrystals (CCA) and zinc oxide (ZnO) were selected as fillers. Carboxylated styrene-butadiene rubber (XSBR) composites (X/C/Z) with dual dynamic crosslinking networks were constructed by constructing ionic bonds between Zn2+ of ZnO and the carboxyl groups of XSBR and CCA, as well as hydrogen bonds between the carboxyl groups of CCA and XSBR. The Fourier transform infrared spectroscopy (FTIR) results confirmed the existence of dual dynamic crosslinking networks in X/C/Z composites. Compared with XSBR/CCA and XSBR/ZnO composites, the dual dynamic crosslinking networks and the synergistic reinforcement of CCA and ZnO endow X/C/Z composites with more excellent physical and mechanical properties. Fixed the CCA content at 5 wt%, the crosslinking density of X/C/Z composites increased with the increase of ZnO content. The tensile strength of the composites also showed an increasing trend, while the elongation at break gradually decreased. Meanwhile, the increase of ZnO content provided more Zn2+ that can complex with the carboxyl groups of XSBR and CCA to form ionic bonds. As a result, the self-healing ability of the composites were enhanced greatly. In this study, using ZnO and CCA as reinforcing/cross-linking fillers, carboxylated styrene-butadiene rubber self-healing composites with excellent properties were prepared by a simple and convenient method, which provided a way for the development of self-healing composites.关键词：carboxylated cellulose nanocrystals;zinc oxide;carboxylated styrene-butadiene rubber;dynamic crosslinking;Self-healing
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发布时间：2023-06-21 - 摘要：With the development of flexible display, colorless polyimide (CPI) films have attracted extensive attention. In this study, rigid aliphatic tetracarboxylic acid (CpODA) was used as the main body, and a variety of commercial diamine monomers were selected to prepare corresponding poly(amic acid)s (PAAs). A series of colorless polyimide films (PIs) were obtained by gradient temperature cyclization. The relationship between ―CF3 side group and amide bond structure to improve the optical transparency and thermal stability of the films was studied. It is found that the introduction of amide structure has a significant effect on the glass transition temperature and thermal expansion coefficient of polymer films, making the glass transition temperature of the film up to 472 ℃, thermal expansion coefficient (CTE, 50‒250 ℃) even less than 10×10-6 K-1. The introduction of trifluoromethyl has a certain effect on the transparency of the film, the optical transparency of T450nm up to 87%, cut-off wavelength (λcutoff) range of 289‒384 nm. It is worth noting that based on the rigid lipid ring structure of CpODA, the minimum heat treatment temperature of PI film is 350 ℃, and it still has good optical transmittance and low CTE value, which provides the basis for the development of CPI.关键词：Polyimide;Colorless transparent polyimide;Semi-aromatic structure;Rigid alicyclic structure
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发布时间：2023-06-21 - 摘要：Two different structures lanthanide-based coordination polymers (Ln2(hbdc)3(H2O)8·6H2O)∞ (Ln-1) and (Ln2(hbdc)3(H2O)8·2H2O)∞ (Ln-2) have been synthesized by changing the adding order of reactants, and TbEu-1, TbEu-2 and GdTbEu-2 (90% Gd3+) were further synthesized. The luminance was analyzed and the temperature-dependent luminescence spectrum was measured. All the luminescent spectra were recorded at solid state. The luminance was ranked as GdTbEu-2>TbEu-2>TbEu-1. For TbEu-2, the value of intermetallic energy transfer efficiency is 67%, after the dilution of 90% Gd3+, this value significantly decreased to 57%. The introduction of cheap Gd3+ and the transformation of the structure enable GdTbEu-2 to achieve temperature sensing between 100 K and 250 K. Compared with unregulated TbEu-1, the range of temperature sensing was doubled, the absolute sensitivity (Sab) and relative sensitivity (Sre) increased by 22 and 3 times, respectively. This phenomenon could be caused by the fact that, the intermetallic distance is larger than 1 nm after Gd3+ dilution, which weakens the intermetallic energy transfer effect, and the less free water molecule thermal motion of structure 2. A series of Sm2xEu2-2x-2 (0.1≤x≤0.9) were further synthesized, showing both visible and near-infrared luminescence, especially Sm3+ displaying excellent spectral gradation in the near-infrared region. This work provides an idea and basis for regulating doping luminescence thermometer and near-infrared temperature sensors.关键词：Lanthanide-based Coordination Polymers;Luminescence;Thermometer;Near Infra-red Emission
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发布时间：2023-06-21 - 摘要：The special molecular structure of polysulfide rubber made it have excellent sealing, anticorrosion, mechanical properties and bonding ability. However, the problems exposed in the use process, such as strong fluidity, short active period and complicated assembly process, greatly limited the assembly level and industrial application of polysulfide rubber. In order to solve the problems above, in this work, liquid polysulfide rubber was used as the core material and polystyrene as the shell material. Microcapsules with uniform size and smooth surface were prepared by solvent evaporation method, so that the viscous polysulfide rubber can be transformed from liquid to solid. According to the adsorption mechanism, evolution process and curing mechanism of wall materials on the surface of polysulfide rubber droplets, the effects of emulsion system conditions, reaction temperature, stirring rate and core-wall mass ratio on the morphology and distribution of microcapsules were investigated to realize the adjustability of microcapsule size and composition. The experimental results showed that the microcapsules with better uniformity can be obtained by using the mixed solution of PVA and NaOA as the emulsion system. This emulsification condition can not only significantly increase the content of polysulfide rubber in the microcapsules (the core content can be increased to 60 wt%), but also greatly reduce the size of the microcapsules, and the average particle size can be as low as 2.23 μm. The above research laid a good foundation for the engineering application of the new generation microcapsule-based sealant, which was of great significance and application value to the assembly automation of sealants.关键词：Key engineering materials;Liquid polysulfide rubber;Polystyrene;Microcapsules;Solvent evaporation method
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发布时间：2023-06-21 - 摘要：In micro-contact printing, the structural stability and shape accuracy of the elastomeric stamp are critical for structural printing with high resolution and precision. When printing alkanethiols on gold surfaces, the self-diffusion phenomenon of organic solvents occurring in the micro-nano pores inside polydimethylsiloxane (PDMS) during the ink dipping process tends to change the mechanical properties and geometry of the stamp, thus affecting the accuracy and effectiveness of the printed patterns. In order to investigate the effect of this self-diffusion phenomenon on the microstructure of the PDMS stamp surface, PDMS stamps with microstructure patterns of different aspect ratios were prepared by casting off on a lithographic silicon wafer template. PDMS stamps with different HDT mass fractions were prepared by immersing the PDMS stamps in 1-hexadecanethiol (HDT) and by controlling the time of self-diffusion of HDT inside PDMS, and based on optical microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements, the effects of the self-diffusion process on the structural stability of the stamp microstructures, surface adhesion and the shape accuracy of the patterns. The results show that the self-diffusion of HDT causes a decrease in both the modulus and adhesion of the PDMS stamped microstructure, and the structural stability of the microstructure with an aspect ratio of 1:1 is relatively best. Secondly, the longer the time of self-diffusion, the higher the content of HDT inside the PDMS, the greater the decrease in the modulus and adhesion of the microstructure, and the higher the shape expansion of its pattern. In addition, the effect of curing agent content on the Young's modulus and adhesion force of PDMS stamp microstructures was investigated by varying the ratio of prepolymer to curing agent. The results can be used as a reference basis for the preparation of PDMS elastic stamps with high structural stability and printing accuracy.关键词：Micro-contact printing;Self-diffusion;Polydimethylsiloxane;Atomic force microscopy;Structural stability
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发布时间：2023-06-21 - 摘要：Low-cost and efficient synthesis of acceptors plays a key role in the commercialization of organic optoelectronic devices. So far, the unfused-ring acceptors (UFRAs) with chlorine terminal groups has rarely been reported in the past years. In this work, a series of A-D-A type chlorinated oligomeric UFRAs with the stepwise extension of π-conjugation lengths (DFPC-2Cl-n (n = 1‒3)) are designed and successfully synthesized via direct C―H arylation. The conjugation length dependence of optoelectronic properties and photovoltaic performances have been systematically investigated, revealing that DFPC-2Cl-2 achieves the highest power conversion efficiency (7.55%) due to the significantly enhanced open voltage (VOC), short current (JSC), and fill factor (FF). The broadest and highest EQE and suitable BHJ morphology of DFPC-2Cl-2-based OSC enabled the highest JSC and FF among the three UFRAs. The combination of chlorine terminal group with the regulated π-conjugation lengths can finely tune the frontier molecular orbital (FMO) levels to obtain new-type oligomeric UFRAs with the elevated VOC, JSC, and FF. The current work demonstrates that direct C―H arylation is a robust and atom-economic strategy to tailor the π-conjugation lengths of UFRAs, which will provide a guidance for the design, synthesis and screening of high-performance non-fullerene acceptors for organic solar cell applications.关键词：Organic solar cell;Oligomeric unfused electron acceptors;Chloric substituent;Atom- and step-economy;C―H direct arylation
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发布时间：2023-06-21
Research Article
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