最新刊期
卷 54 ， 期 9 ， 2023
- 摘要：We report a new kind of mechanophore and the corresponding polyurethane that exhibit a vividly detectable mechanochromism. Such optical features rely on the synergistic coupling of an azulene (Az) core and two spiropyran (SP) units into one chromophore. The use of the acid-, and light-induced chromogenic ring-opening reactions of SP and the acid-induced protonation reaction of Az reveals that the three subunits in this mechanophore can be activated orthogonally, thus generating switchable optical responses with high color contrast. The polyurethane is mechanically activated using sonication (in solution state) and tensile deformation (in bulk state), which exhibits a green-to-blue mechanochromism. Due to its excellent mechanochromism, the mechanochromic polymer shows great potential in stress sensing and damage detection. Our strategy based on the coupling of multi-responsive organic dyes into one chromophore will open a new avenue to regulate the sensitivity of mechanochromophores, and to develop the stimuli-responsive materials with multiple functions.关键词：Mechanochromic polymers;Photochromism;Acid induced chromism;Spiropyran;Azulene;Polyurethane
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发布时间：2023-08-21
Rapid Communication
- 摘要：The huge consumption of polymeric materials in the world has led to a dramatic increase in plastic waste, which has caused pervasive environmental pollution and severe waste of material resources. Crosslinking the polymer segments by noncovalent bonds is an effective method for developing healable, degradable, and recyclable polymeric materials, which could be a fundamental solution to the global plastic waste crisis. However, the noncovalently crosslinked polymeric materials usually exhibit low mechanical robustness, hindering their practical applications. In this feature article, we summarized the recent research progress of our group on hydrogen-bonded supramolecular polymeric materials with high mechanical robustness and various functionalities. Based on the synergistic effect of high-density hydrogen bonds, the cooperation of hydrogen bonds and dynamic covalent bonds, and the regulation of the microstructures of the polymeric materials, we have developed a series of healable, degradable, and recyclable supramolecular polymer materials that simultaneously possess high strength and high toughness. Our results not only break the bottleneck of poor mechanical properties of noncovalently crosslinked polymeric materials, but also reconcile the mutual exclusiveness between the strength and toughness of polymer materials. These studies provide new ideas for the development of the high-performance sustainable alternatives to traditional polymer materials. Moreover, we have developed a series of hydrogen-bonded functional supramolecular polymeric materials, and their applications in flexible electronic devices, solid-state lithium batteries, and underwater adhesives are also introduced in this feature article.关键词：supramolecular materials;Polymeric materials;Hydrogen bonds;Mechanical properties;sustainability
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发布时间：2023-08-21
Feature Article
- 摘要：As a mild and green chemical reaction method, mechanochemistry has received more and more attention in recent years. The use of grinding, ultrasound and other forms of mechanical force to control the polymerization reaction is an important polymer synthesis method, which has shown unique advantages in the control of polymerization process and the preparation of stimuli-responsive materials. This paper summarizes the polymerization induced by mechanical forces such as ultrasound and ball milling, including free radical polymerization, oxidative polymerization, ring-opening metathesis polymerization, condensation polymerization and click polymerization. At the same time, the effects of mechanical stress, ultrasonic cavitation and piezoelectric effect on the polymerization process were discussed. Finally, we summarized the research of force induced polymerization and discussed the challenges and future directions in this field.关键词：Mechanochemistry;Mechaoredox Catalysis;Polymer mechanochemistry
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发布时间：2023-08-21
Review
- 摘要：This study described the efficient synthesis of two oxolactone monomers ((3R,7R)-M1 and (3S,7R)-M2). The monomers were synthesized using (R)-methyl-3-hydroxybutyrate, which is an alcoholysis product of poly(3-hydroxybutyrate) (P3HB). The introduction of phenoxymethyl resulted in diastereoisomers with different polarity that could be separated by column chromatography. The monomers were polymerized via ring-opening polymerization using MeAl[salen] as the catalyst, and the polymerization behaviour was investigated. P((3R,7R)-M1) and P((3S,7R)-M2) with controlled molecular weights and chain-end groups were prepared. The linear structure of the polymers was further confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS) and 1H nuclear magnetic resonance (1H-NMR). P((3S,7R)-M2) is a semi-crystalline polyester. Additionally, stannous octanoate (Sn(Oct)2 was used as a catalyst to achieve the depolymerization and recovery of the P((3R,7R)-M1) in a dilute solution of 1,3,5-mono-trimethylbenzene. This strategy enables P3HB upcycling, extending the material's life cycle and expanding the range of high-value closed-loop recyclable polyether esters.关键词：Ring-opening polymerization;Closed-loop recycling;Degradable polyester;Poly(ether-ester)
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发布时间：2023-08-21 - 摘要：Polymethacrylate block copolymers with three-arm star structure were designed and synthesized by micro-scale Cu(0)-catalyzed reversible deactivation radical polymerization. The structure and properties of the copolymers were studied by nuclear magnetic resonance, gel permeation chromatograph and rheological. Firstly, micro-scale Cu catalyzed polymerization platform was designed for the synthesis of poly(methyl methacrylate) and poly(laurylmethacrylate) intiated by 1,1,1-tris(2-bromoisobutyryloxymethyl)ethane (3f-BiB). Fast polymerization, controlled reaction process, wide range of molecular weight and narrow distribution were achieved under the micro-scale Cu catalyzed reversible deactivation radical polymerization platform. Poly(methyl methacrylate)-block-poly(dodecyl methacrylate) copolymer was efficiently obtained in the assembled tandem microreactor system. The result demonstrated that controlled structure, adjustable molecular weight, narrow distribution and three-arm star structure were achieved by employing the micro-scale Cu catalyzed copolymerization. Additionally, responsive adjustment of the entanglement performance to the alkane solvents, improved viscosity retention rate of lubricating oil at different temperatures were achieved when the three-arm star polymethacrylate block copolymer was used as lubricating oil additives.关键词：Micro-scale;Cu catalalyzed;Reversible deactivation radical polymerization;Three-arm star polymer
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发布时间：2023-08-21 - 摘要：A new strategy of constructing the bidirectional density gradients based on vinyl sulfone (VS) surfaces was developed, which could promote the direct growth of the polymer brushes on the bioactive ligand density gradient surface without any modifications. The chips with well-defined densities of the ligands prepared using such strategy can be used for specific detection of corresponding antibody in complex biological fluids. Fluorescein was selected as the small biomolecule model to develop and demonstrate this strategy. Bidirectional density gradient samples composed of fluorescein and zwitterionic polymer brushes were prepared, and poly(sulfobetaine methacrylate) (PSBMA) was selected as preferable inert ligand by evaluation of the Pearson coefficient of fluorescein antibody (anti-FITC) on the sample surface. The samples showed excellent specific and anti-nonspecific binding towards anti-FITC and bovine serum albumin (BSA), respectively. The fluorescein chips with well-defined adsorption property of anti-FITC were prepared by this strategy. And we demonstrated the chip with high fluorescein density in BSA and 50% fetal bovine serum (FBS) solution displayed high specificity and sensitivity towards anti-FITC. In addition, the universality of the strategy was evaluated using human chorionic gonadotropin antibody (anti-HCG) and beta-2-microglobulin antibody (anti-BMG) as biomacromolecule models. Overall, such strategy can not only act as universal method for preparing bidirectional gradient samples, but also provide theoretical guidance for the preparation of bio-detection chips.关键词：Bidirectional density gradient;Vinyl sulfone surface;Fluorescein;Poly(sulfobetaine methacrylate)
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发布时间：2023-08-21 - 摘要：Flexible sensors can sense external stimuli and convert them into electrical signals that are easy to be analyzed statistically. They have enormous application potential in human motion detection, health monitoring, and human-machine interaction and other fields. It is important to develop flexible sensors with high ductility, transparency, conductivity and stability. Conductive elastomer is the key core material of flexible sensor. At present, transparent flexible sensors mainly use ionic conductive materials, including hydrogels, organic gels, ionic gels and ionic conductive elastomers. Ionic conductive elastomers are composed of ionic conductors and elastic polymer networks, which have conductive mechanism similar to skin, wide operating temperature range, high transparency and excellent reversible tensile-shrinkage performance, which are suitable to be used as transparent flexible sensors for human-machine interaction. In this work, the soft-hard crosslinked copolymer-based lithium ionic conductive elastomers were prepared via a one-step click polymerization reaction, and used as the flexible strain sensors for monitoring finger bending and Morse Code transmission information. The hard segment component consists of liquid crystal molecules, which tend to orderly arrange during the membrane stretching process, and enhance the mechanical properties of the elastomer. The soft segment is composed of polyethylene glycol dimethacrylate oligomer (Mn = 750 g/mol), which can not only increase the breaking elongation and transparency of ionic conductive elastomers, but also the ether oxygen segment contained can dissociate and transport lithium ions, and improve the conductivity of ionic conductive elastomers. By optimizing the proportion of components, ion conductive elastomers with different mechanical properties, transparencies, and conductivities can be obtained. The maximum elongation at break is 1280%, the maximum fracture stress is 5.08 MPa, the maximum modulus is 17.21 MPa, the transmittance is over 80%, and the maximum conductivity is 2.5 mS/cm. The ionic conductive elastomers with the best comprehensive properties possess high strain sensitivity with corresponding gauge factor values of 2.89, 4.61, and 5.39 in the strain range of 0‒200%, 200%‒350%, and 350%‒550%, respectively. This one-step soft-hard segment crosslinked copolymer strategy provides a new idea for preparing high-performance transparent ionic conductive elastomers.关键词：Copolymer;Ionic conductive elastomer;Liquid crystal;Flexibility;Sensor
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发布时间：2023-08-21 - 摘要：Aiming at manipulating the molecular shapes and phase structures of mesogen-jacketed liquid-crystalline polymers (MJLCPs) polymers, we designed a new MJLCP 1P containing the flexible "benzene-benzyl ester-benzene" units in its side-chains and another MJLCP 2P as reference containing the rigid "benzene-ester-benzene" units. 2P renders extremely stable lamellar liquid crystalline phase probably with sheet-like conformation. However, 1P forms lamellar liquid crystalline phase at the low-temperature range and columnar liquid crystalline phase at the high-temperature range, probably with sheet-like and rod-like conformations, respectively. We also proposed the mechanisms for transitions of molecular shapes and phase structures of 1P: at the low temperature range, the "benzene-benzyl ester-benzene" units mainly adopt the tans conformation and hence the side-chains behave like flexible rod-like mesogens, leading to the sheet-like molecules and their further lamellar packing; at the high temperature range, the "benzene-benzyl ester-benzene" units mainly adopt the gauche conformation and thus increases their jacketing effect on the main-chain, generating rod-like molecules and further columnar packing. In this work, through incorporating the flexible connecting units, we successfully manipulated the molecular shapes and phase structures of a MJLCP. This work will pave a way to tune molecular shapes and phase structures of side-chain liquid crystalline polymers.关键词：mesogen-jacketed liquid crystalline polymers (MJLCPs);lamellar liquid crystalline phase;Columnar liquid crystalline phase;sheet-like molecule;rod-like molecule
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发布时间：2023-08-21 - 摘要：The poly(vinyl alcohol)(PVA)-iodine complex has been widely used in industry due to its unique optical dichroism. The properties of PVA-iodine composites are closely related to their interaction modes and strength. However, due to the complexity of the studied systems, there is still no consensus on the exact structure of the PVA-iodine complex. According to the number of PVA chains in the complex model, the existing models can be divided into the single-chain model and multi-chain model. The single-chain model is proposed based on the helical structure model of the amylose-iodine complex. Thus, to investigate the most probable structure of the PVA-iodine complex, the interactions between PVA-iodine and amylose-iodine have been investigated by single-molecule force spectroscopy in deionized (DI) water and KI/I2 solution, respectively. When the single amylose chain is stretched in DI water, the sugar ring will undergo a chair-boat conformational transition, showing a shoulder plateau on the force-extension (F-E) curves. When it is stretched in KI/I2 solution, a long plateau (~40 pN) will appear except the shoulder plateau, which corresponds to the unwinding of the helical structure in the amylose-iodine complex. However, the F-E curves of PVA obtained in the KI/I2 solution only contain a single peak and do not exhibit a long plateau similar to that of amylose in the KI/I2 solution. Moreover, the F-E curves of PVA obtained in DI water and KI/I2 solutions with different concentrations can be superposed well after normalization. The experimental results show that the interaction between PVA and iodine ions is different from that between amylose and iodine ions. In other words, the PVA-iodine complex does not exist in a helical structure, and the single-chain model is not suitable to describe the interaction between PVA and iodine. This study lays the foundation for further study of the multi-chain model of the PVA-iodine complex.关键词：PVA-iodine complex;Amylose-iodine complex;Single-molecule force spectroscopy;Helical structure
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发布时间：2023-08-21
Research Article
- 摘要：Biodegradation is an effective route for polymer materials to go back into the natural circumstance, and biodegradable polymers is regarded as an important solution to the plastic pollution problem. Characterization of biodegradability is therefore crucial for the development, modification, and application of degradable polymer materials. This review aims at the aerobic biodegradation of polymer materials and introduces typical characterization techniques, focusing on two aspects: degradation products and materials after degradation. For degradation products, the characterization are mainly carried out from three aspects: CO2 generation, O2 consumption, and determination of small molecular degradation products. In addition, the characterization of biomass can indicate the impacts of polymers on organisms and the environment during the biodegradation process. The characterization of materials after degradation involves composition changes, structure changes, and service performance changes such as weight loss and mechanical property deterioration. There may be a heterogeneous distribution of degradation in polymer materials. One reason is that the enzymatic decomposition starts from the surface and gradually develops into the matrix. In this paper, the principles of various characterization methods are introduced and typical examples are supplied. In the future, rapid biodegradation evaluation method is expected and comprehensive analysis of various characterization results is used to help the precise design and preparation of controllable biodegradability of polymers.关键词：polymer material;Biodegradation;Degradation product;Material characterization;Performance change
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发布时间：2023-08-21
Review (Special Topic: Techniques of Polymer Characterization)
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