最新刊期
卷 53 ， 期 11 ， 2022
- 摘要：Machine learning (ML) plays an important role in the investigation and development of polymer material genomes. The success of ML-based studies strongly depends on the design and selection of feature descriptors, which reasonably portray chemical and structural characteristics of polymer materials. In this review, we elucidate a few of descriptors commonly utilized for effectively constructing the link between polymer structures, chemical compositions and aggregate structures, macroscopic properties. In addition, the database, especial for the polymer materials, is also explicitly listed, although the continuous development of specific database is still in a large demand. The research progress of ML methods in the field of polymer materials in recent years is reviewed, as well as successful applications and achievements. In particular, the solutions to deal with the small amount of data or the high cost of expensive data are also presented. According to the current research progress, the difficulty and challenge of ML applications in the field of polymer materials are discussed as well.关键词：Polymer material genomes;Machine learning;Relations between structures and properties;Prediction and optimization of target properties;Multi-objective optimization
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发布时间：2024-10-08 - 摘要：From the earliest knots to various contemporary fabrics with exquisite patterns, weaving has been throughout the entire history of human civilization. The highly ordered warp and weft threads synergistically endow the woven materials with unique topologies and rich mechanical properties. Inspired by this, researchers attempt to integrate the woven topologies into polymer science, and develop new polymeric materials with well-defined structures—woven polymers. Woven polymers are a kind of polymer networks constructed by cross-nodes as the basic units and cross-linking with each other, which are mainly divided into two categories: one is crystalline woven polymers, which possess long-range ordered molecular woven threads, mainly including metal organic frameworks (MOFs) and covalent organic frameworks (COFs), etc.; the other type is flexible woven polymers, which are generally unordered over long ranges, while the incorporation of woven crosslinks can significantly enhance the physical and chemical properties of the polymers, similar to what the macroscopic woven structures do. In the woven polymer networks, the dynamically woven cross-links can effectively dissociate to dissipate energy under external stimuli, giving the entire polymer networks excellent dynamicity and toughness. Meanwhile, the warp and weft threads can slip relatively after the dissociation of the dynamic site, so that the stress could be transmitted to the entire polymer network, and the strength and resilience of the network are improved while the stability of the weaving topology is maintained. Therefore, the woven polymers have broad application prospects in the construction of mechanically stable crystalline framework materials and new flexible functional polymer materials. However, as an emerging polymer material system, woven polymers still need further development in terms of structure optimization, performance exploration and application expansion. This review first focuses on the molecule knots, introducing various construction strategies in detail and expounding their vital roles in the development of woven polymers. Then, we summarize the construction methods, performance tests and related attempts on application of existing crystalline woven polymers and flexible woven polymers. Finally, the key scientific issues and challenges in the field of woven polymers are discussed and the future application prospects are prospected. It is firmly believed that woven polymers are a very bright field of research, possessing new and interesting aspects waiting to be explored and discovered. It is anticipated that this review will provide references and clear veins for the rapid development of woven polymers, and new approaches for the research of new functional polymer materials.关键词：Woven polymers
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发布时间：2024-10-08 - 摘要：Living systems have the capacity to effectively regulate the assembly of molecules into natural materials with outstanding functionalities via controlling the assembly process. Inspired by nature, great efforts have recently been focused on controlling the assembly process, not only enriching materials formats, but also assisting further understand the complex assembly mechanisms. In this review, we firstly introduce the current considerable progresses via tuning the assembly process, as well as illustrating that the reported strategies are insufficient to regulate precisely the assembly process because it is difficult to independently control the thermodynamics of assembly and molecular assembly rates. Then we summarize our recent research progress on precise controlling the molecular assembly process via a novel method, solvent recrystallization. The two key parameters, recrystallization temperature and temperature change rate, can independently control the assembly thermodynamic environment and molecular aggregation rates. Thus, the same assembly units including small molecules and polymers can be assembled into desired materials with controllable sizes and adjustable molecular packings.关键词：Molecular self-assembly;Solvent recrystallization;Assembly process
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发布时间：2024-10-08
Review
- 摘要：Photodeformable crosslinked liquid crystal polymer fiber actuators have potential applications in soft robots and other fields. However, due to the limitations of processing methods, it is still a great challenge to fabricate fiber actuators that can undergo large and direction-controllable light-induced bending at room temperature. Here, the main-chain liquid crystal oligomer with controllable molecular weight is synthesized by the Michael addition reaction between primary amines and liquid crystal monomers containing azobenzene or phenyl benzoate mesogens, respectively. On the basis, the cross-linked liquid crystal polymer fiber is obtained through dip-drawing the melt oligomer followed by the radical polymerization. The chain extension reaction between the primary amine and liquid crystal monomers effectively decreases the crosslinking density of the polymer network, thus lowering the glass transition temperature. Meanwhile, the alignment and crosslinking processes are decoupled by the strategy that the oligomer is stretched first and then the polymerization is implemented, which ensures that mesogens in the fiber are aligned along the stretching direction. Accordingly, the aligned fiber exhibits reversible light-induced bending at room temperature, whose maximum bending angle is close to 60°, and furthermore the bending direction can be adjusted by the light irradiation direction. The main-chain crosslinked liquid crystal polymer fiber with large and direction-controllable deformation has great potential in the field of soft robots. In addition, the method of processing oligomers and then polymerizing actuators is expected to be combined with the template method and 3D printing to fabricate actuators with complex shapes, promoting the development of photoresponsive flexible actuators and other fields.关键词：Liquid crystal polymers;Photodeformation;Azobenzenes;Fibers
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发布时间：2024-10-08 - 摘要：To solve the problem that chitin photonic crystals material cannot exhibit visual color, a chitin liquid crystal film material with nematic structure is designed and constructed. The liquid crystal film material is dried from nematic liquid crystal formed by self-assembly of carboxylated chitin nanocrystals (T-ChNC) in the aqueous phase through electrostatic repulsion and steric hindrance between carboxyl groups. The liquid crystal film exhibits high transparency under natural light, and due to the light interference effect of the highly aligned structure, the film exhibits a bright blue color under the crossed polarizer. The density of carboxyl group on the surface of T-ChNC has significant effects on the range of electrostatic repulsion force of T-ChNC in water, which in turn affects the orientation degree of T-ChNC in the film. When the carboxyl content is higher than 0.6 mmol/g and the concentration of T-ChNC dispersion is higher than 5%, the dried T-ChNC films have uniform color. It is shown that T-ChNC films with strong hydrophilicity have sensitive responsiveness on ambient humidity and solvent, swelling and changing color in high humidity atmosphere, and showing various colors in ethanol solutions with different concentrations. Compared with the traditional chitin chiral photonic crystal material, the color of the nematic T-ChNC liquid crystal film is visible and can be controlled by design, which has broad application potential in bio-optical anti-counterfeiting and encryption materials.关键词：Chitin nanocrystal;Self-assembly;Nematic orientation;Liquid crystal material
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发布时间：2024-10-08 - 摘要：Donor-acceptor conjugated polymer P1 was synthesized by introducing a thermally removable tert-butoxycarbonyl (Boc) group into diketopyrrolopyrrole (DPP). The solubility study of polymer P1 shows that it has good solubility in common organic solvents (such as tetrahydrofuran, toluene, chloroform, etc.), and can be processed in solution. Thermogravimetric analysis and infrared spectroscopy show that the Boc group of P1 can be removed at an appropriate temperature and the insoluble polymer P2 can be formed. The maximum absorption wavelength of the polymer P1 film is 829 nm, the highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) level are -5.25 and -3.62 eV, respectively. The photodetector with P1/PC61BM as active layer exhibits a maximum specific detectivity of 8.20×1011 Jones and dark current density of 6.49×10-8 A/cm2 under -0.1 V bias. The maximum absorption wavelength of the polymer P2 film is 771 nm, the HOMO and LUMO levels are -5.30 and -3.54 eV respectively. The dark current density of the photodetector with P2 as hole transport layer and P3HT/PC61BM as active layer is 3.84×10-9 A/cm2, and the maximum specific detectivity is 3.96×1012 Jones under -0.1 V bias. Compared with the device without hole transport layer and the device with PEDOT:PSS as hole transport layer, the device with P2 as hole transport layer shows lower dark current density and higher maximum specific detectivity. The results imply that polymer P2 with insoluble property is a potential candidate for hole transport material. This work provides new ideas for the selection of hole transport layer materials, the structural design of conjugated polymer molecules and the improvement of photodetector performance.关键词：Tert-butoxycarbonyl (Boc);Conjugated polymer;Solubility;Annealing;Photodetector
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发布时间：2024-10-08 - 摘要：In order to solve the problems that microcracks occurring in solid electrolyte which may affect the cycling performance and capacity of lithium-ion battery, a self-healing solid-state polymer electrolyte was prepared based on the combination of a poly(NBPEO-b-NBZwit) network, imidazole-based ionic liquid (EMITFSI) and LiTFSI. In this work, polymers with different proportions of NBPEO and NBZwit were prepared, and their self-healing and electrochemical properties were studied. The PEO component endows the polymer with good lithium ion transport capacity, while the zwitterionic ions realize self-healing through ion coupling. At the same time, because the polymer was mixed with ionic liquid, the interaction between zwitterionic groups and ionic liquid further improves the repair efficiency of SHPE2. The results of mechanical tensile tests showed that the healing efficiency of the mechanical strength reached 91.4% after healing at 60 ℃ for 10 h. Due to the plasticization of ionic liquid and the dissociation of zwitterions to lithium ions, its ionic conductivity can reach up to 7.42×10-5 S·cm-1 at room temperature. The results of electrochemical performance tests shows that the electrochemical window of SHPE2 reached 5.0 V versus Li/Li+, because of the existence of norbornene skeleton. The discharge specific capacity of the lithium metal battery assembled by SHPE2 is 124.3 mAh·g-1. The lithium metal battery assembled by healed SHPE2 can still maintain the discharge specific capacity of 123.2 mAh·g-1 after 50 cycles with a coulombic efficiency of 99.17%. The polymer containing PEO side chain and zwitterion was prepared by ring opening polymerization, which provides a scheme for the design of self-healing polymer electrolyte materials.关键词：Polymer electrolyte;Self-healing;Poly(ethylene oxide);Zwitterion;Ring-opening metathesis polymerization
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发布时间：2024-10-08 - 摘要：Molecular weight is an important parameter of polyelectrolytes. However, there are certain limitations in each of the current methods for measuring the molecular weight of polyelectrolytes. In this work, we propose a novel method to measure the molecular weight (chain length) of polyelectrolytes by using atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS). The chain lengths of poly(sodium styrenesulfonate) (PSSNa) with narrow molecular weight distribution in high vacuum and water are measured. The SMFS experimental results show that the statistical result of the chain length of PSSNa in water is significantly larger than that obtained in high vacuum. PSSNa is a strong polyelectrolyte and will ionize when dissolved in water, which will lead to a more extended conformation in water than that in high vacuum. In this case, the distance between the two positions on the PSSNa chain corresponding to the gripping point of the AFM tip and the anchor point of the substrate adsorption is relatively far. Therefore, the force-extension (F-E) curves of PSSNa obtained in water have longer apparent contour lengths than those obtained in high vacuum. The average chain length of PSSNa obtained in water is close to the Monte Carlo simulation results. This work shows that for a rigid polyelectrolyte, when it adopts an extended conformation (such as the dissolution of PSSNa in the water environment), SMFS can be used to roughly estimate the average length of the polymer chain.关键词：Polyelectrolyte;Chain length;Single-molecule force spectroscopy;Poly(sodium styrenesulfonate)
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发布时间：2024-10-08 - 摘要：The physicochemical properties of carbon dioxide (CO2)-based copolymer can be enhanced by the regulation of the chain structure, especially for the CO2/propylene oxide (PO) copolymer (PPC), which is plagued by low glass transition temperature. Introducing cyclohexene oxide (CHO) as the third monomer in terpolymerization is an important way to improve the thermal property of PPC. However, the reaction process of such terpolymerization is complicated and its kinetics study is still in its infancy. Herein, the kinetic behaviour of terpolymerization of PO/CHO/CO2 was thoroughly investigated by virtue of the Fineman-Ross equation and in situ FTIR study, in the presence of aluminum porphyrin complex formed homogeneous catalysis. Results showed that the monomeric reactivity ratios of both PO and CHO were smaller than 1 under a low temperature of 60-70 ℃. Through regulating the monomer feed ratios, the random terpolymer could be facilely achieved with tunable thermal and mechanical properties. The reactivity ratio of CHO boosted significantly at high temperatures, which is favorable for the formation of block copolymers. The in situ FTIR analysis demonstrated that the catalytic system could quickly initiate the polymerization even at very low viscosity at 70 ℃. With the increase of polymerization temperature, the production of cyclic carbonate will be greatly increased, and the chain unzipping reaction of polymer can be obviously observed.关键词：CO2 terpolymerization;Kinetics;Reactivity ratio;Aluminum porphyrin
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发布时间：2024-10-08 - 摘要：Adsorption is an effective method for removing pollutants from water. Among them, homogeneous adsorbents can capture the adsorbates in the medium by effective collision. However, there are some difficulties in effectively removing themd from water. Compared with homogeneous adsorbents, heterogeneous adsorbents are easily separated from the system, but the interaction with pollutants is relatively weak, which may cause secondary pollution. Here, a thermos-responsive tubular adsorbent was presented by dynamic assembly of V-shaped aromatic amphiphiles. The tubular wall based on the assembly of 120-degree folded aromatic segment is very suited for the trap of organic pollutants. In addition, the aromatic pores have excellent water solubility for the surrounding of hydrophilic ethylene oxide segments, showing remarkable removal capacity as well as fast sorption kinetics with homogeneous adsorbent characteristics. The removal capacity is found to be 126.5 mg/g for bisphenol A (BPA) and 95.4 mg/g for ethinyl estradiol (Eo), respectively, due to the formation of hydrophobic tubular pores in aqueous environment. In addition, the equilibrium time of tubular adsorbents were just 60 min for BPA and 50 min for Eo to achieve complete removal efficiency, which is attributable to the existence of preferable collision with pollutant in aqueous environment for its spherical topology with an efficient hydrophilic surface. Due to the lower critical solution temperature (LCST) effect of ethylene oxide segment, the surface of adsorbent became hydrophobic by thermal triggers, resulting in a phase separation between water and adsorbent. Thus, the removed pollutants as well as adsorbents are easily separated from water through a simple centrifugation. Therefore, a new sewage treatment route is proposed based on the temperature responsive behaviour of supramolecular porous adsorbent. At room temperature, the tubular adsorbent with homogenous characteristics can be used to rapidly trap organic pollutants in water. Then, the adsorbent and adsorbate complexes are converted into solid phase by raising the temperature up to 65 ℃, which can be effectively separated by centrifugation. By further dialysis by water, the absorbent can be recovered and used for next utilization. During five adsorption and desorption cycles, the removal efficiency of supramolecular porous adsorbent was maintained, demonstrating excellent performance in sewage treatment. The strategy combined advantages of homogeneous and heterogeneous adsorption provides a new insight for water purification.关键词：Supramolecular assembly;Phase transition;Porous materials;Adsorption
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发布时间：2024-10-08 - 摘要：Segmented distribution is one of the key factors affecting the properties of polyurethane (PU). Exploring its effect on the properties of PU with cyclic hard segments will be the key to the successful development of high-performance and functional PU. Controlling the similarity of hard segment content, a series of IPDI-based PU with different segment distributions were synthesized using polycaprolactone diol (PCL-diol) with different molecular weights, isophorone diisocyanate (IPDI), and 1,4-butanediol (BDO). Herein, PCL-diol with different molecular weights was used as the soft segment, and IPDI and BDO were used as the hard segment. The chemical structures of PCL-diol with different molecular weights and the IPDI-based PU with different segment distributions were characterized by Fourier transform infrared spectroscopy, superconducting nuclear magnetic resonance and X-ray diffraction. The surface morphology of IPDI-based PU was observed using a polarizing microscope, 3D ultra-depth of field microscope and atomic force microscope, and its crystallization behavior was analyzed by differential scanning calorimetry. Furthermore, the tensile properties of IPDI-based PU were explored by an electronic universal testing machine and photos of the shape of stretched splines before and after fracture. The results show that only soft segment crystals exist in IPDI-based PU, and with the aggregation of the soft segment, that is, with the increase of the molecular weight of the soft segment, the size of the formed spherulites increases, and the crystallization ability of the soft segment is also enhanced. Meanwhile, IPDI-based PU with different segment distributions have similar stress-strain curves and similar tensile properties. However, the more dispersed the hard segment, the stronger the steric hindrance effect, which makes the oriented crystallization of the soft segment more difficult, the tensile strain more difficult to be fixed, and therefore, the more excellent elasticity is exhibited.关键词：Polyurethane;Segment distribution;Crystallized behavior;Elastic property
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发布时间：2024-10-08 - 摘要：A series of poly(3-(triethoxysilyl)propyl methacrylate) (PTEPM) oligomers (oT), polymethylmethacrylate (PMMA) oligomers (oM), and block copolymers of PTEPM-b-PMMA with narrow molecular weight distributions were synthesized using RAFT polymerization. Two PTEPM-b-PMMA copolymers with the PMMA blocks of different molecular weights were co-assembled with the oligomers of PMMA or PTEPM to form various ordered nanoscale structures, such as lamellae, cylinders, and spheres. PTEPM block could be crosslinked to form silsesquioxane core (i.e., SiO1.5), when the obtained co-assembly materials were immersed in hydrochloric acid atmosphere. After appropriate separation and purification, the bimodal polymer grafted nanoparticles (PGNPs) with different microstructures could be prepared. Using this assembling-crosslinking-dispersing (ACD) method and adjusting the molecular structure of block copolymer and the ratio of the three components (PTEPM-b-PMMA, oT, and oM), the structural parameters of bimodal PGNPs, including the shape and size of core, grafting density, molar ratio between long and short brushes, and length of long brushes, could be precisely controlled. By adjusting the proportions of two block copolymers with the PMMA blocks of different molecular weights and the amounts of oMs, bimodal PGNPs with different molar ratios of long and short brushes could be prepared. By adjusting the molecular weight of the long brush and the amounts of oM, bimodal PGNPs with different lengths of long brushes were obtained. By adjusting the amounts of oM and oT, bimodal PGNPs with the same core shape but different sizes were obtained. By adjusting the amounts of oM, bimodal PGNPs with the same core weight but different shapes (cylindrical or spherical) were obtained. These nanoparticles are ideal model models for studying the relationship between the microstructures and properties of polymer nanocomposites.关键词：Block copolymer;Polymer grafted nanoparticles;Silica dioxide;Bimodal brushes
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发布时间：2024-10-08 - 摘要：Polypropylene/ethylene-propylene random copolymer/high density polyethylene (PP/EPR/HDPE) blends with core-shell particles were prepared by melting mixing to study the effects of core-shell particles on rheological behaviors of PP based system. Morphology observation through SEM confirmed the core-shell structure of dispersed particles. Different rheological behaviors were studied by rheometer through dynamic test, stress relaxation test, cycled strain sweep test and modulus recovery test. Results showed PP system with core-shell particles presented obvious long-time relaxation, which was not observed in PP/EPR binary blend with low EPR content. It was believed the obvious long-time relaxation came from interfacial relaxation of dispersed phase with larger size, leading to a relaxation plateau. While for PP/EPR binary blend with low EPR content, relaxation modulus showed a quick drop. The different relaxation behaviors between above samples indicated that the introduction of HDPE in PP/EPR system could enlarge the size of dispersed phase through formation of core-shell particles. Cycled strain sweep test proved that PP/EPR/HDPE had satisfactory structure stability after loading large strain, meaning that materials performance could quickly recover once the external strain was unloaded. It was believed that long-time relaxation and structure stability of PP/EPR/HDPE both resulted from larger dispersed phase. This study proved again that HDPE could work as equivalent rubber in PP system by formation of core-shell particles.关键词：polymeric core-shell particle;polypropylene blend;Rheological behavior
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发布时间：2024-10-08 - 摘要：A series of propylene/1,3-butadiene (BD) block copolymers with high molecular weight (>1.3×105) and narrow molecular weight distribution (1.8~2.0) were prepared via “one-pot, two-step” method by using dimethylpyridine amine hafnium/[Ph3C][B(C6F5)4]/AliBu3 as catalyst system under mild conditions. By Varying the reaction time for each step and BD dosage in the second step, the block length of each block and composition of the soft block could be easily tuned. Molecular weight and molecular weight distribution, thermal properties, microstructure and mechanical properties of the obtained block copolymers were clearly characterized by high temperature gel chromatography (GPC), differential scanning calorimetry (DSC), high temperature nuclear magnetic (NMR), tensile test, etc. The block copolymers contain both a hard iPP block and soft propylene/BD random copolymer block. It was revealed that 1,3-BD was randomly inserted into the molecular chain via both 1,2- and trans-1,4-insertion manners, and the amount of the latter was about six times that of the former. The copolymers showed high melting temperature (Tm ≈ 158 ℃) and very low glass transition temperature (Tg around -70 ℃). The obtained block copolymers with both hard iPP segments and propylene/1,3-BD random copolymer block helped to achieve both high rigidity and toughness simultaneously. As proved, the block copolymers showed high tensile strength (≥33 MPa) and elongation at break (up to 800%). The above results indicated that via tuning the hard and soft block composition during the two-step copolymerization of propylene and BD, block copolymers with much improved tensile properties could be easily obtained. Incorporation of a very soft propylene-BD random copolymer block plays a vital role in iPP toughening. The research results will provide new idea for the development of the iPPs with excellent mechanical properties.关键词：Propylene;1;3-Butadiene;Coordination copolymerization;Block copolymer;Toughening modification
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发布时间：2024-10-08
Research Article
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