最新刊期
卷 52 ， 期 9 ， 2021
- 摘要：The design of mechanoresponsive polymers has attracted great attention. However, the design of a new mechanochromophore for mechanochromism still remains a huge challenge in this field. This work reports the design and synthesis of a new spirooxazine mechanochromophore, which are introduced into PDMS polymer network. A color change from colorless to blue is first demonstrated by UV irradiation of a solution of small molecule spirooxazine and the polymer, and the UV induced color change can fully recover within seconds after the removal of UV light. This recovery is much faster than that of a similar spiropyran mechanochromophore, which takes tens of seconds to achieve decoloration. Uniaxial stretching experiments verify that the polymer can exhibit excellent mechanochromic behavior during the stretching process. CIE diagram shows that the polymer changes from colorless to purple red during the stretching process. When the mechanical force is removed, the polymer instantly turns into blue and returns to colorless within seconds. Cyclic loading-unloading experiments also show that the mechanochromism is robust and fully reversible. In summary, this article introduces a new mechanochromophore for the construction of crosslinked PDMS with both photochromism and mechanochromism. Due to its excellent mechanochromism and rapid recovery, the mechanochromic polymer shows great potential in stress sensing and flexible sensors.关键词：Responsive polymer;Mechanochromophore;Mechanochromism;Reversible
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发布时间：2023-05-22
Rapid Communication
- 摘要：Vascular disrupting agents (VDAs) have aroused increasing interest due to their great potential in tumor therapy. In this work, recent progresses of our group in the polymeric nanodrug of VDAs are reviewed. As compared to combretastatin A4 phosphate (CA4P), a small-molecule prodrug of combretastatin A4 which has entered Phase Ⅲ clinical trials, poly(L-glutamic acid)-g-methoxy poly(ethylene glycol)/combretastatin A4 (PLG-CA4 or CA4-NPs) shows significantly improved the tumor blood vessels targeting and enhanced therapeutic effect due to the low permeability of nanodrug in solid tumors. However, the tumor microenvironment changes significantly after CA4-NPs treatment, which can lead to a series of host responses, such as the increased expression of VEGF-A, CXCR4 as well as the polarization of tumor-associated macrophages toward a M2-like phenotype. Several small molecule inhibitors or antagonists were used to combine with CA4-NPs for inhibiting tumor growth and metastasis. As a result, a significant reduction in tumor volume and prolonged survival time of tumor-bearing mice were observed. In addition, the levels of hypoxia and MMP-9 were regulated by using CA4-NPs, and thereby drug controlled release systems with high selectivity to tumor-microenvironment were constructed to achieve drug activation with high tumor selectivity. This significantly enhanced the therapeutic effect of MMP9-activated prodrugs and hypoxia-activated prodrugs. Based on the tumor-specific coagulation microenvironment created by the VDAs, a coagulation targeting peptide (GNQEQVSPLTLLKXC, termed A15)-decorated poly(L-glutamic acid)-graft-maleimide poly(ethylene glycol)/combretastatin A4 conjugate (A15-PLG-CA4) was constructed as a self-amplifying nanotherapeutic tumor homing platform working through a chain reaction mechanism. After administration to tumor-bearing mice, A15-PLG-CA4 started a chain reaction cycle consisting of intratumoral hemorrhage, target FXIIIa amplification, blood clot binding and CA4 release in tumors to achieve a high tumor targeting efficiency. Furthermore, this self-amplifying tumor-targeting platform can be used for the selective delivery of other drugs to tumors. This work highlights the potential of the polymeric nanodrug of combretastatin A4 for tumor therapy. A brief perspective is also provided for future research directions about the VDAs nanodrug.关键词：Vascular disrupting agents;Nanodrug;Glutamic acid;Self-amplifying;Tumor-homing
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发布时间：2023-05-22 - 摘要：Entropy, one of the elementary parameters in thermodynamics, is a central concept in statistical mechanics. In macromolecular systems, entropic effects, predominantly from the conformational entropy of a chain, play an essential role in both microstructural organization and macroscopic properties. In striking contrast to enthalpic interactions, entropic effects seem to be elusive and even lead to counterintuitive performance due to the statistical nature of entropy. Thus, exploring the entropic effects in macromolecular systems is of significant importance in elucidating the physical origin behind many complex phenomena, and has become one of the most important directions in the interdisciplinary fields covering polymer physics and soft matter physics. One particular aspect lies in how to manipulate entropic effects to tune the structural organization and thereby develop new functional systems, based on a fundamental understanding of the rules governing the ectopic effects. Here, we summarize our recent progress in proposing and developing entropic strategy in the structural control of macromolecular systems. Firstly, we elucidate the unique rules of the entropic effects, including entropic ordering and entropic forces, and propose the concept of superentropic effect. The significance, principles, and approaches regarding the entropic strategy are then described. Some applications of entropic strategy in various macromolecular systems, such as polymer nanocomposites, polymer gel networks, and biological macromolecules, are also presented. We finally seek to discuss future directions and identify open problems regarding the future progress of the entropic strategy. We hope that this article will promote further efforts toward fundamental research and the wide applications of entropic strategy in elucidating physical mechanisms, developing new types of functional materials, and beyond.关键词：Entropic strategy;Superentropic effect;Conformation statistics of polymer chain;Entropic force;Soft matter physics
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发布时间：2023-05-22
Feature Article
- 关键词：Aggregation-induced emission;Self-assembly;molecule aggregates;Covalent organic frameworks;DNA
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发布时间：2023-05-22
Review
- 摘要：Constructing the surface coating with both biological inertness and responsive antithrombotic activity is an ideal way to solve the problem of foreign-material induced thrombosis in the applications of blood-contact medical devices. In this work, a thrombin-responsive hydrogel coating is designed and prepared based on one-step photocuring. The coating can sustainably resist non-specific protein adsorption and specifically inhibit thrombus formation in a thrombosis responsible way. Poly(ethylene glycol diacrylate) (PEGDA) and a thrombin-cleavable peptide (Pep) were used in the photo-initiated polymerization system. PEGDA worked as the main skeleton component as well as crosslinker, and the peptide mainly as the thrombin-cleavable crosslinker. The fibrinolytic molecule, tissue plasminogen activator (t-PA), was loaded during the hydrogel forming. The results showed that the coating could keep resistance to non-specific protein adsorption in normal blood environment and specifically trigger the release of t-PA in the presence of thrombin so that the nascent clot can be lysed. Moreover, the hydrogel coating could maintain the basic skeleton and thus the resistance to protein adsorption could be kept even after degradation by thrombin. In general, this research provides new ideas for optimizing the anti-thrombotic properties of blood contacting medical devices.关键词：Anti-protein adsorption;Hydrogel coating;Anti-thrombotic surface;Fibrinolysis
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发布时间：2023-05-22 - 摘要：Multicomponent polymerization (MCP) could efficiently synthesize multi-functional polymers with structural diversity. In order to further expand MCP and construct the polymers with potential application, in this work, we report an efficient Cu-catalyzed MCP technique that enables the synthesis polyphosphonylamidines of high molecular weight (up to 54000 g/mol) and high yield (up to 90%) from monomers of diphenyl phosphate azide (DPPA), diynes and diamines, in N,N-dimethylformamide (DMF) at room temperature for 4 h. The obtained polymers have more potential in application after post-functionalization, compared with the polymers prepared by the sulfonyl azide. Reactive oxygen species responsive polyphosphonylamidines with special construction are prepared by using thioketal diamine as polymeric monomer, and these polymers exhibit excellent degradation property by ROS-triggered. The structure, molecular weight and repeat units of all synthetic polymers are determined by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and MALDI-TOF. The effects of rigidity and flexibility of diynes and steric hindrance of diamines on the MCP are investigated. This polymerization method provides a powerful approach for MCP to synthesize functional polymers and broadens the application fields of polymer science.关键词：Multicomponent polymerization;Polyphosphonylamidine;Diphenyl phosphate azide;ROS-degradable polymer
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发布时间：2023-05-22 - 摘要：With the change of the condensing agent (n-hexane) content in the process of ethylene/1-hexene copolymerization, three polymerization environments of pure gas phase environment, poor n-hexane environment and rich n-hexane environment were established. The "comonomer effect" and the "cosolubility effect" collectively affect the copolymerization reaction. The results show that the polymerization activity decreases in the pure gas phase environment, due to the capillary condensation inside the dry particles, and the comonomer effect dominates. In the poor n-hexane environment, because of the high molar concentration ratio of 1-hexene/ethylene in the wet particles at the initial stage, the polymerization activity remains basically unchanged under the competition of the comonomer effect and the cosolubility effect. With the increase of n-hexane content, co-solubility effect dominates, and the polymerization activity rises. The liquid-containing particle polymerization mode that the molar concentration ratio of 1-hexene/ethylene in the gas phase and slurry environment is the best maximizes the polymerization activity. In the rich n-hexane environment, the polymerization activity decreased slightly due to the dilution of 1-hexene concentration by n-hexane. The short chain branch degree of polyethylene products is almost the same in the pure gas phase environment and the poor n-hexane environment, slightly higher than that in the rich n-hexane environment.关键词：Ethylene polymerization;cosolubility effect;comonomer effect;liquid-containing particle polymerization
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发布时间：2023-05-22 - 摘要：Silk fibroin shows promising potential in dielectric and electrical energy storage application since that its structure unit has a large dipole moment (3.5 D) and its molecular structure has both soft and hard segments. In this study, for the first time, the dielectric properties of silk fibroin film under high electrical fields are investigated and the emphasis is given on the relationship between secondary structures and dielectric properties under high electrical fields. The results show that under high electrical fields, the change in the secondary structures of the silk fibroin is closely associated with its dielectric behavior. Specifically, the increase of the β-sheet structure is beneficial for the electrical strength enhancement and suppressing the dielectric loss of silk fibroin film. In addition, the high-field dielectric properties are significantly boosted by optimizing the preparation process of the silk fibroin film. The optimized film has a discharge energy density of 7.43 J/cm3 and a charge-discharge efficiency of 79.8% under an electrical field of 500 MV/m, which demonstrates a promissing energy storage capability. This work provides basic data for exploring the application of silk fibroin in the dielectric field and also gives reference for further optimization of molecular structure in the future.关键词：Silk fibroin;High electric field;Dielectric properties;Energy storage properties
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发布时间：2023-05-22 - 摘要：The instant heat dissipation performance of electronic devices plays a decisive role in their service life, but contradicts with the continuous demand in their reducing size. The key to solving this technical bottleneck is to develop and use insulative polymer materials with high thermal conductivity, expecially those simutaneously with recyclability, which can further reduce the cost, protect the environment and prolong their sustainablility. Based on these, we used polyformaldehyde (PFA) and 4,4'-diaminobenzylaniline (DABA) with special aromatic-amide structure as raw materials, introduced local microscopic ordered structures into the resin curing network via the strong hydrogen bond interaction between amide bonds to increase the propagation free path of phonon, and synthesized a novel polyhexahydrotriazine thermosetting resin (DABA-PHT). Its prepolymerization process and mechanism, curing technology and performances in thermal conductivity, degradability and recycliability were investigated. The results show that water can be used as a catalyst to effectively accelerate the prepolymerization reaction and shorten the prepolymerization time greatly; the amidic N―H bonds did not participate in the crosslinking reaction; DABA-PHT resin can be easily synthesized and processed, and demonstrates satisfying mechanical property, heat resistance, degradability and recyclability. Its thermal conductivity is 0.38 W·m-1·K-1, nearly twice as much as those of ordinary epoxy resins. Therefore, DABA-PHT can be expected to be used to prepare recyclable thermosetting resin matrix composites with high thermal conductivity.关键词：Poly(hexahydrotriazine);Recyclable;Intrinsic thermal conductivity;Hydrogen bond interactions
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发布时间：2023-05-22 - 摘要：A silicone modified polyurethane (SiPU) was synthesized with 4,4'-diphenylmethane diisocyanate (MDI), polytetrahydrofuran ether glycol (PTMEG), hydroxyl terminated polydimethylsiloxane (HO-PDMS), 1,4-butanediol (BDO) as raw materials and its structure was characterized by hydrogen nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectroscopy (FTIR). The effect of HO-PDMS content on the thermal stability and hydrophobicity of polyurethane was investigated by thermogravimetric analysis (TGA) and water contact angle (WCA) test. The results showed that the SiPU coating had the best performances when the content of silicone was 9 wt%. Then the superhydrophobic coating was easily prepared by spraying SiPU as the matrix and fluorosilane modified SiO2 nano particles (FAS-SiO2 NPs) with different sizes (25 and 15 nm) as fillers. The effects of FAS-SiO2 NPs size and content on the hydrophobicity of the composite coating were also studied by WCA test. It was proven that the composite coating possessed the best performances when the mass ratio and content of FAS-SiO2 NPs were 4:1 and 60 wt%, respectively. The WCA and hysteresis angle were 153.3° and 6.3°, respectively. After heated at 200 °C for 1 h, the composite coating was still superhydrophobic. Moreover, the abrasion test showed that the composite coating was always superhydrophobic before the aluminum alloy substrate was exposed. The anti-icing test result showed that the composite coating decreased the freezing temperature effectively and delayed freezing time obviously, compared with uncoated surface and coating without fillers. Considering that the composite superhydrophobic coating can be prepared easily in large scale by spaying and has great anti-icing performance, it holds great potential in the fields of superhydrophobicity and anti-icing.关键词：Superhydrophobic;Polyurethane coating;Anti-icing;Composite coating
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发布时间：2023-05-22 - 摘要：MOFs/polymers composite materials (ZIF-8@PDMAPMA) were fabricated by step method (Route I) or one pot method (Route Ⅱ and Route Ⅲ), and characterized by PXRD, FTIR, SEM, TEM and TGA. ZIF-8@PDMAPMA composite materials were core-shell nanoparticles in which ZIF-8 crystal particles were coated by flexible polymer chains. The effects of synthesis methods on the morphology of ZIF-8@PDMAPMA nanoparticles were explored. The shape of nanoparticles was spherical or similar to ZIF-8 crystal profile. The size and distribution of the nanoparticles were controlled by emulsification of monomers, organic ligands and polymer chains in the process of nanoparticles formation, and its size was 50 nm with regular distribution. Additionally, the effective encapsulation of MOFs crystal particles by polymer flexible chains led to the decrease of N2 adsorption capacity of ZIF-8@PDMAPMA nanoparticles. However, the hydrophilicity of ZIF-8@PDMAPMA nanoparticles was remarkably enhanced, and it had good dispersibility and excellent stability with uniform size distribution of particles in water. Moreover, benzalkonium chloride was loaded and then controlled release by ZIF-8@PDMAPMA nanoparticles in the aqueous with the maximum loading of 0.05 g/g and the release rate of 82%. The results of adsorption kinetic models showed that the multilayer adsorption behavior of the nanoparticles for benzalkonium chloride had occurred in the pores of ZIF-8 in the internal and the flexible polymer chains on the surface of the nanoparticles presented. Finally, it can be expected that the combination of flexible polymer chains and rigid MOFs crystals will greatly improve the stability of MOFs in aqueous phase, and broaden its applications.关键词：MOFs;Polymer composite;Nanoparticles with core-shell structure;Wettability;Controlled release
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发布时间：2023-05-22 - 摘要：4,4′-Diphenyl-6,7′-biphthalazin-1,1′(2H,2′H)-dione (6,7-DBD) and 4,4′-diphenyl-7,7′-biphthalazin 1,1′ (2H,2′H)-dione (7,7-DBD) were synthesized. The copolymerization behaviors of two DBDs and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one with 1,4-bis(4-fluorobenzoyl)benzene were investigated, separately. N-heterocyclic copoly(aryl ether ketone ketone)s with different locations of side-phenyl groups (P-CDs and P-TDs) were obtained. The intrinsic viscosities (ηint) of the copolymers are in the range of 0.5-1.1 dL/g. P-CDs perform the easier preparation process and higher ηint than P-TDs. The glass transition temperature of P-CDs ranges from 254 ℃ to 296 ℃, and the retention rate of storage modulus is up to 67% at 250 ℃, which is higher than that of P-TDs with the similar polymerization composition. Both copolymers are soluble in commom solvent, such as N-methylpyrrolidone and 1,1,2,2-tetrachloroethane. The tensile modulus is in the range of 1.56-1.78 GPa, the tensile strength is in the range of 50.1-102.9 MPa, the elongation at break is in the range of 11.0%-18.1%, and the insulation properties are little short of the same. In summary, P-CDs exhibit better heat resistance, solubility, and mechanical proteties than P-TDs . It can be found that adjusting the distribution of side phenyl in main chains can significantly affect the thermal stability, mechanical property, solubility, and preparability of the polymer, which provides an attempt direction for the preparation of high-performance polymers with high heat resistance and solubility.关键词：Molecular structure;Poly(aryl ether ketone ketone)s;Phthalazinione;Solubility;Thermo-resistance
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发布时间：2023-05-22
Research Article
- 摘要：Small angle neutron scattering (SANS) is a powerful tool to characterize multi-scale structures in macromolecules. Deep penetration and H/D isotope labeling make it a unique scattering method. To make it more familiar to the users, basic principle of SANS, instrumentation and experimental skills were firstly demonstrated. Then typical applications in the fields of polymer solution, polymer blends, nanocomposites, crystallization, gels, porous materials and biomacromolecules were introduced. As for the data analysis of complex systems, such as biomacromolecules, in addition to the traditional data analysis methods, advanced methods such as the ab initial analysis and Reverse Monte-Carlo (RMC) simulations provide more detailed information. Combine with small angle X-ray scattering (SAXS), static light scattering (SLS), electron microscope (EM) et al., SANS enables us to solve the structure and interaction of more complicated systems such as interaction of biomacromolecues and solvation of polymers in mixed solutions. As the China Spallation Neutron Source (CSNS) was officially opened to the users around the world in 2018 and SANS instruments equipped with various sample environments are being built, more opportunities are opened to the SANS communities domestically and abroad.关键词：Small angle neutron scattering;Macromolecules;Multi-scale and multi-phase;Structure Characterization;China spallation neutron source
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发布时间：2023-05-22 - 摘要：As a powerful tool, Raman spectroscopy is widely used in the characterization of polymer structures. Along with the rapid development of Raman technology such as resonance Raman spectroscopy, scanning angle Raman spectroscopy, high-resolution Raman imaging, polarized Raman spectroscopy, and surface-enhanced Raman scattering, the application range of Raman spectroscopy has been continuously extended. In this paper, we first introduced the basic principle and the composition of the Raman equipment, and then we summarized the experimental skills of Raman technology and the issues that need attention in data processing. The difference between the infrared spcectroscopy and the Raman spectroscopy was discussed. Afterwards, we reviewed the latest applications and research progress in the fields of polymer structure characterization by using Raman technology in recent decade. The applications include the following six aspects: the macromolecular chain conformation, the aggregation state of polymers, the calculation of the polymer crystallinity, the macromolecular chain orientation, the structural transformation under the external fields, and the identification of the chemical or physical composition in polymer blends. Last, the development of Raman spectroscopy in polymer research was prospected. It is hoped that this review could be helpful for the one who tried to obtain the information about the polymer structure from Raman spectroscopy.关键词：Raman Spectroscopy;Structure Characterization;Principle;Application
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发布时间：2023-05-22 - 摘要：Size exclusion chromatography (SEC), which is also called gel permeation chromatography (GPC), is a liquid chromatography that sorts molecules according to their hydrodynamic volume in solution by using columns packed with porous particles. It is the most frequently used technique to characterize the molecular weight and its distribution of naturally occurring and synthetic macromolecules. Multi-detector SEC combining differential refractive index, ultraviolet/visible, viscosity and multi-angle laser light scattering detectors is a powerful tool to study the shape and conformation of polymer chains in solution. Here we summarize the separation mechanism of SEC and show that the retention of polymer in SEC is an equilibrium, entropy-controlled and size-exclusion process. In order to achieve a pure SEC separation according to the size of polymer chains, enthalpy interaction between polymer chains and the packing particles should be prevented. Then we introduce the know-how to perform successful SEC experiments with a focus on the choice of eluent, column and detector, as well as sample preparation, optimization of experimental conditions and data analysis. Especially, the eluent composition should be properly optimized according to the analysed polymer sample and the column overloading should be avoided, before accurate results can be obtained by SEC. Finally, we show some examples of the recent applications of SEC in polymer characterization such as molecular weight and its distribution of polymers, composition of multi-component polymer mixtures, conformation and flexibility of polymer chains, and characterization of branched polymers. More dramatically, delayed elution of high molar mass polymers was observed in SEC at high flow rates, which is not due to polymer degradation. This abnormal elution behaviour results from a chromatographic mode transition from SEC to slalom chromatography, which originates from the coil-stretch transition of polymer chains in elongational flow through the SEC columns. It is shown that SEC can provide abundant structure parameters and their distributions of polymer chains in solution, and plays a pivotal role in the analysis of natural and synthetic macromolecules. This review aims to provide a theoretical and experimental guidance for SEC beginners, hoping to inspire more applications of SEC in the field of polymer science.关键词：Size exclusion chromatography;Polymer characterization;Molecular weight and distribution;Conformation
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发布时间：2023-05-22
Review (Special Topic: Techniques of Polymer Characterization)
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