最新刊期
卷 53 ， 期 12 ， 2022
- 摘要：We explore and compare the reaction efficiency of DNA with organic small molecule compounds in solid-phase synthesis and solution coupling. Multiple DNA-organic small molecule complex structures have been synthesized efficiently by the method of DNA solid-phase synthesis, whose structures and molecular weights are characterized by matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF). Then, the assembling behaviors of DNA-pyrene complex in aqueous phase have been explored by transmission electron microscopy and dynamic light scattering, whose assemblies are expected to be applied to the study of drug package release.关键词：DNA;Solid-phase synthesis;Solution coupling;Assembly
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发布时间：2024-10-08
Rapid Communication
- 摘要：Polymeric single chain-colloid hybrid nanoparticles are functional building blocks with the characteristic lengths of single chains. These hybrid nanoparticles integrate the characteristics of polymers and colloids and lay the foundation for the construction of sub-10 nm superstructures and single chain devices. Central to the synthetic methodology, the precise architecture and scalable fabrication of polymeric single chain-colloid hybrid nanoparticles are fundamental to the discovery of novel structure-property relationships and are essential for materials applications. In this review, we summarize recent progress in the synthesis of polymeric single-colloid hybrid nanoparticles, including (1) intramolecular crosslinking of polymeric single chains, (2) intramolecular cyclization through polymerization, and (3) chemical bonding between single chains and colloidal surfaces. For intramolecular crosslinking, precursor chains with diverse topologies (e.g. rings, bottlebrushes, and dendrimers) contribute to unique conformational and structural characteristics for single chain nanoparticles (SCNPs). More precise regulation of the precursor sequences, the tertiary structures of SCNPs, and the responsive intramolecular crosslinking are expected in future study. To address the challenge of scalable synthesis of SCNPs, electrostatic-mediated intramolecular crosslinking has been an efficient method. By utilizing electrostatic repulsion, intramolecular crosslinking can be achieved at relatively high solid contents. For intramolecular cyclization through polymerization, polymer networks constructed through cyclization of single living species is the key. This method has been underestimated; in fact, it has the potential to sequentially generate topologies like "chain-crosslinked sphere-chain", in analogy to the polymerization of block copolymers. The scalable synthesis of SCNPs through intramolecular cyclization is still challenging since gelation occurs at low reaction conversion. Theoretical and experimental research are expected to collaborate to generate new understanding in regulating single species cyclization during polymerization and the SCNP network construction. For chemical bonding between single chains and colloidal surfaces, single chain@colloids can be achieved in a fast and scalable manner. The types of colloids should be largely expanded to cover a wide range of functional nanoparticles. In addition, precise regulation of the composition, number, and spatial arrangement of single chains at colloidal surfaces are critical to develop functional polymeric single chain-colloid hybrid nanoparticles.关键词：Single chain nanoparticles;Intramolecular crosslinking;Functional colloids;Spatial Compartment
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发布时间：2024-10-08 - 摘要：Ever-shrinking pattern features present challenges for the semiconductor industry. Directed self-assembly (DSA) of block copolymers (BCP) has been demonstrated as one high throughput and low cost manufacturing candidate for the next-generation of nanolithography. The thermodynamically immiscible polymer blocks self-assemble into the ordered nanostructures with varied morphologies, and the feature size is dependent on the Flory-Huggins interaction parameter (χ) and the molecular weight (N) of BCP according to the self-consistent mean field theory. Design, synthesis, and self-assembly of novel high χ low N BCP is the long-term target for the community of polymer chemistry and materials science with the aim to achieve small size microphase separation domains. This review focuses on self-assembly of silicon-containing block copolymers for sub 5 nm nanolithography. Silicon-containing block copolymers not only exhibit high χ but also improve etch contrast property, which are considered as the promising materials for nanolithography. After a brief introduction of DSA, the main body is divided into three sections according to the chemical structures, including poly(dimethylsioxane)-based BCP, poly(silicon containing styrene)-based BCP, and poly(hedraloligomeric silsesquioxane)-based BCP. Each section covers self-assembly of bulk polymer and/or thin film, from historic initial study (>5 nm) to the recent progress (<5 nm). Synthesis, characterizations, χ, assembly conditions, feature sizes are discussed in detail. Finally, the challenges and opportunities are proposed. We hope this review would provide insights into polymer science and nanolithography technology.关键词：Silicon-containing block copolymer;Self-assembly;Nanolithography;Sub 5 nm;Flory-Huggins interaction parameter
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发布时间：2024-10-08
Review
- 摘要：Construction of antibacterial surface coating is an ideal way to solve iatrogenic infection caused by adhesion growth bacteria on the surface of medical devices. Therefore, in this study, chitosan/silk nanofiber (CHI/SNF) multilayer film is prepared by layer-by-layer self-assembly technology with electrostatic interaction as the driving force. The assembly process of this multilayer film is traced by an ultraviolet spectrophotometer (UV-Vis), and its morphology is analyzed using scanning electron microscopy (SEM). Then, BBR-CHI/SNF multilayer film is obtained by introducing the natural antibacterial berberine (BBR). The in vitro drug release behavior and antibacterial activity against S. aureus and P. aeruginosa. The test results show that the drug loading of the multilayer film can be controlled by adjusting the number of layers. The multilayer film has anti-bacterial adhesion and certain antibacterial performance. After loading BBR, through the synergistic effect of BBR and CHI in multilayer, the antibacterial performance is improved and the growth of S. aureus and P. aeruginosa is inhibited, with the inhibition rates of (59.62±4.28)% and (51.65±3.77)%, respectively. In conclusion, we have successfully constructed a drug loading multilayer film with both antibacterial and anti-bacterial adhesion functions. This multilayer film is easily prepared and its properties are easy to control and flexible substrate. Therefore, it has good prospects for application in the field of antibacterial on the surface of biomedical materials.关键词：Layer by layer self-assembly;Chitosan;Silk nanofiber;Berberine;Antibacterial property
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发布时间：2024-10-08 - 摘要：The sialidase-mediated desialylation plays an important role in the dynamic regulation of sialic acid (SA) on the cell surface and is involved in a variety of physiological and pathological processes. For one thing, the in vitro simulation and in-depth study of this important process will help us deeply understand many physiological processes related to SA, and for another, it will also lay a foundation for the construction of biomimetic materials involving enzymes. Here, we used glycopeptide nanofibers with a large exposure of SA on the surface as the starting structure and then replicated the sialidase-mediated desialylation process by adding sialidase to the solution. The results showed that the added sialidase indeed led to the cleavage of SA on the fiber surface and thus triggered the morphological transformation of glycopeptide fibers. We also regulated the kinetics of SA removal by changing the sialidase concentration, and the results showed that the rate of removal of sialic acid determined the evolution path of glycopeptide fibers. Slow removal of SA led to the gradual evolution of the initial double-helix glycopeptide fibers into micelles, and the high rate of SA excision allowed the initial double-helical glycopeptide fibers to eventually evolve into twisted nanoribbons. In addition, the application of this strategy in cell culture has also been demonstrated.关键词：glycopeptides;Self-assembly;sialidase;morphology transformation
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发布时间：2024-10-08 - 摘要：The solution self-assembly of crystalline polypeptoids to form hierarchical nanostructures with tailorable morphologies and functionalities has attracted increasing attention. While, the common crystalline polypeptoids obtained by ring-opening polymerizations (ROPs) are mainly with linear alkyl side chains. The self-assemblies of crystalline polypeptoids with aromatic side chains are rarely reported. In this study, a novel N-substituted-N-thiocarboxyanhydride (NNTA) monomer with bromophenyl side group was designed and synthesized, namely N-4-bromobenzylglycine-N-thiocarboxycanhydride (NBrG-NTA). Using poly(ethylene glycol) amine as macroinitiator and acetic acid as a promoter, the controlled ROPs of NBrG-NTA in DMAc were achieved, which produced diblock copolymers poly(ethylene glycol)-b-poly(N-4-bromobenzylglycine) (PEG-b-PNBrG). The structures of the diblock copolymers were confirmed by 1H-NMR and FTIR spectra. By adjusting monomer to initiator feed molar ratios, PEG44-b-PNBrG7 and PEG44-b-PNBrG12 were prepared with high yields (>80%) and narrow molecular weight distributions (Đ<1.06). The chain lengths of PNBrG blocks were closed to the feed molar ratios, which showed the good controllability of the polymerizations. DSC measurements showed that PNBrG chains of both homopolymers and block copolymers had a good crystallinity. Therefore, crystallization and solvophobic interaction-driven self-assembly of PEG-b-PNBrG in alcoholic solvents was systematically studied, and the morphologies of the assemblies were characterized by TEM. After annealing in n-butanol at 100 ℃ for 4 h, PEG44-b-PNBrG7 was adequately dissolved, and "bamboo leaf"-like assemblies were formed after incubated at 25 ℃ for 2 h, and the size of the assemblies increased when the incubation time prolonged to 12 h. When the annealing time in n-butanol was cut down to 2 h, irregular spherical micelles were obtained at first due to the inadequate dissolution of partial PEG44-b-PNBrG7 chains, while the fully dissolved chains assembled to spindly nano-sheets, and finally nano-sheets aggregated around the irregular spherical micelles to form "sea urchin"-like assemblies. To the case of PEG44-b-PNBrG12, after annealing in n-octanol at 140 ℃ for 4 h, it assembled to "dandelion"-like nanoparticles with similar formation processes to the "sea urchin"-like assemblies.关键词：Polypeptoids;N-Thiocarboxyanhydrides;Ring-opening polymerization;Bromophenyl group;Self-assembly
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发布时间：2024-10-08 - 摘要：In order to effectively improve the conductivity and flexibility of carbon nanofibers, eccentric core-shell nanofibers were prepared via coaxial electrospinning technique with polyvinylpyrrolidone (PVP) as the core solution and polyacrylonitrile (PAN) and PVP as the shell solution. And then, N-doped cross-linked carbon nanofibers were prepared due to the melting of the thermoplastic polymer PVP during the high-temperature carbonization process, resulting in the formation of cross-linking points between adjacent nanofibers. NiCo2O4 decorated N-doped cross-linked carbon nanofiber electrodes were obtained by growing NiCo2O4 nanoneedles on the surface of carbon nanofibers via hydrothermal synthesis reaction. Due to the structural advantages of electrode materials and the synergistic effect of carbon nanofibers and NiCo2O4 nanoneedles, the prepared NiCo2O4 modified N-doped cross-linked carbon nanofiber electrode exhibits excellent electrochemical behavior (specific capacitance is 1186.4 F·g-1 (197.5 mA·h·g-1) at the current density of 0.5 A·g-1, capacitance retention of 74.5% after 1×104 charge-discharge cycles). The asymmetric supercapacitors assembled by prepared electrode materials powered electronics successfully, which provides a new research idea for the development of flexible electrodes.关键词：Carbon nanofiber;Bimetallic oxide;NiCo2O4;Flexible electrode;Supercapacitor
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发布时间：2024-10-08 - 摘要：The severe energy crisis has become a huge obstacle to the industrialization process and economic development. In addition to developing new energy, improving the utilization efficiency of existing energy is one of the effective means to solve energy problems. In order to solve the contradiction between serious waste and discontinuous supply of thermal energy, the management and storage technology of thermal energy have been developed rapidly in recent years. Based on the advantages of high latent heat, suitable phase transition temperature, and thermal stability, poly(ethylene glycol) (PEG) is one of the most widely used materials of solid-liquid phase change. However, the polymer-based PCM undergoes solid-liquid phase changes between crystalline and molten states during use, which is prone to leakage and failure. Coaxial electrospinning utilizes a polymer with high melting point to encapsulate phase change material (PCM) as a core layer, which is an effective means to reduce the leakage of PCM. Biodegradable poly(L-lactic acid) (PLLA) is an environment-friendly material with excellent mechanical properties, which becomes an alternative to petroleum-based polymers. The glass transition temperature of PLLA is close to the melting point of PEG Although there is no obvious latent heat during the glass transition of PLLA, the thermal conductivity of PCM might be influenced by the change of heat capacity. Therefore, the thermal property of PCM can be regulated by coupling of heat latent of phase regulation and glass transition. More importantly, both PLLA and PEG have good biocompatibility, which may broaden the application in the field of biomedical application. In this study, core-shell fibers with good thermal management properties were prepared by coaxial electrospinning, in which PEG and PLLA are used as the core and shell layers, respectively. The core-shell structure is tested by transmission electron microscopy (TEM), and analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD). The thermal storage properties, thermal stability and mechanical properties of phase change materials are investigated. The core layer of PEG is well coated by PLLA and the maximum coating ratio reaches 48.8 wt%. The biggest crystallinity of PEG reaches 56.3%. Due to the latent heat capacity of solid-liquid phase transition of PEG and the change of thermal capacity of PLLA, the phase change material with the core-shell structure has good thermal management performance, which provides an opportunity for broadening the application field of polymer-based phase change materials.关键词：Coaxial electrospinning;Phase change material;Thermal management performance;Thermal insulation efficiency
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发布时间：2024-10-08 - 摘要：High-strength and super-toughened poly(butylene terephthalate) (PBT)/poly(ethylene terephthalate-co-terephthalate-1,4-cyclohexanediol ester) (PCTG)/glycidyl methacrylate grafted POE (POE-g-GMA) blends were prepared by melt blending, and their toughening mechanisms were systematically analyzed. The impact behaviors of the materials with different toughness were recorded using a high-speed camera. Scanning electron microscopy (SEM) photographs showed that POE-g-GMA was uniformly dispersed in the blend with a particle size of about 0.3 μm. PCTG possesses good compatibility with PBT, and could inhibit the crystallization of PBT. With the increase of PCTG content (0 wt%-40 wt%), the glass transition temperature (Tg) of the blends increased linearly and the crystallinity decreased gradually, but the toughness increases slightly. As the content of PCTG reaches 50 wt%, the brittle-ductile transition occurs, with the notch impact strength 1060 J/m and the elongation at break 360%, which is 17 and 20 times of PBT, respectively, but the tensile strength does not decrease significantly (45 MPa, decreased by 18%). The microscopic morphology of the impact fracture section shows that a large amount of cavitation and yield deformation occurred in the material at this content. Further analysis shows that more mobile amorphous fraction (MAF), lower Tg, and crystallinity are the main reasons for the brittle-ductile transformation of the material, and the heat generation at the moment of impact further contributes to the yield deformation. Finally, the deformation of the material with time in both brittle fracture and ductile fracture modes was recorded by an instrumented impact tester and high-speed camera to provide an experimental basis for further understanding of the impact behavior.关键词：Poly(butylene terephthalate);Copolyester;High strong and super tougheness;Self-heating;Impact behavior
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发布时间：2024-10-08 - 摘要：Carbon deposition tends to occur in commercial polyimide during electric breakdown due to the high carbon content, resulting in short circuit between interlayers of the corresponding metallized film capacitors. In order to solve this problem, molecular design is employed by introducing alicyclic structure with low carbon content into polyimides in this study. Specifically, the alicyclic polyimides (PI-1-PI-5) are prepared from alicyclic dianhydride of cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and aromatic diamines. Defect-free films derived from alicyclic polyimides are obtained whose chemical structures have been assigned by FTIR. In addition, it is indicated from the XRD results that the alicyclic polyimides are amorphous. When it comes to the dielectric properties, dielectric constants of 3.83-4.74 (at 103 Hz) are achieved owing to the easier polarization of extranuclear electrons in cycloalkane structure in alicyclic polyimides compared to the all-aromatic polyimide such as Kapton (εr=3.5). Besides, the values of dissipation factor are in the range of 0.49% to 1.29% (at 103 Hz). The flexible alicyclic structure contributes to frictionless reorientation and low dielectric loss. The band gap of 3.96-4.13 eV and Weibull breakdown strength of 243-547 MV/m in the alicyclic polyimides are acquired. As a result, the highest theoretical energy density is as high as 5.91 J/cm3 obtained in PI-3. The last but not the least, thanks to the reduced carbon content (carbon-hydrogen ratio: 1.16-1.29), compared to the commercial polyimide of Kapton (carbon-hydrogen ratio: 1.60), carbon deposition behavior has been greatly suppressed because the hydrogen and oxygen elements would escape easily from the breakdown point in the form of water vapor under the high-temperature arc. Furthermore, the dielectric films of alicyclic polyimides would facilitate the self-healing behavior of the corresponding metallized film capacitor.关键词：Polyimide;Alicyclic structure;Dielectric property;Self-healing
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发布时间：2024-10-08 - 摘要：Carbazole group functionalized isotactic polypropylene (P-C) samples were prepared via direct copolymerization of propylene and α-olefin bearing terminal carbazole group.The carbazole group could absorb ultraviolet light and exibibit blue-purple luminescence under 365 nm ultraviolet light, which may endows the material with anti-photooxygen aging property. 13C-NMR data showed that the propylene/11-carbazole-1-undecene copolymer(P-Cs) have high tacticity. In order to maintain the excellent mechanical properties of isotactic polypropylene, the incorporation of comonomer was controlled at 0.45 mol%-1.67 mol%. The P-C samples with different carbazole group contents were studied via UV aging and the UV-oxidative stability tests. After the same aging time, when large and deep cracks were observed on the surface of the iPP sample, only the P-C1 sample with the lowest carbazole group content showed small cracks on the surface, while the P-C2 and P-C3 samples with higher content of carbazole groups had no cracks. Tensile tests revealed that losses in tensile properties of the P-C samples were far less compared to that of the pure iPP sample. At 120 h, the mechanical properties of the iPP samples were completely lost. Under the same conditions, the tensile strength of the P-C1 samples remained above 98%, and the tensile strengths of the P-C2 and P-C3 samples were significantly improved. The DSC data showed that the melting temperature (Tm) of the iPP samples decreased by 7 ℃ after UV irradiation, while the Tm of the samples in the P-C group decreased by at most 2 ℃. which indicated that the introduction of carbazole groups could stabilize the thermal properties of the samples under UV irradiation. GPC test results showed that the thermal properties and molecular weghts of polypropylenes with carbazole group were well maintained after the UV aging process, and that the degradation reaction has been significantly inhibited. In conclusion, the introduction of carbazole groups could effectively enhance the UV-oxidative stability of polypropylene.关键词：Isotactic polypropylene;Carbazole;Copolymerization;UV aging
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发布时间：2024-10-08 - 摘要：The macromolecules exhibit the multiscale aggregation features and consequently show the unique memory effect for subsequent re-crystallization. The origin of memory effect was usually related to the survival of crystallization-associated structures after melting, which has a close correlation with molecular architecture. In this work, a series of 1-butene/4-(3-butenyl)toluene (PBBT) copolymers were prepared by dimethylpyridine amine hafnium/[Ph3C][B(C6F5)4] catalyst system to introduce the steric 4-(3-butenyl)toluene co-units with π-π interaction into the poly(1-butene). Differential scanning calorimetry was employed to systematically study the influence of melt temperature, melting time and crystallization temperature on memory effect of PBBT copolymers. The results showed that the presence of 4-(3-butenyl)toluene co-units induced the occurrence of melt memory effect, which accelerated re-crystallization kinetics without changing the formed crystal modification of tetragonal phase. The triggered memory effect exhibits the maximum strength within the intermediate melt temperatures. Interestingly, as the melting duration increased, the exothermic peak value of cooling crystallization in PBBT copolymers moved to high temperature, demonstrating the melting-enhanced strength of memory effect. This development behavior of memory effect in PBBT is significantly different from the customary decaying evolution reported previously. Moreover, it was found that melt memory effect of PBBT copolymers is also strongly dependent on the crystallization temperature and its strength can be enhanced by lowering crystallization temperature.关键词：1-Butene copolymer;Crystallization kinetics;Melt Memory effect
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发布时间：2024-10-08 - 摘要：The stress and structural behaviors of non-entangled comb polymer melts under start-up shear flow were studied by molecular dynamics simulations, and compared with those of linear polymer. It is found that the stress-strain response of the unentangled comb polymer with short branched chain is almost the same as that of the linear polymer under different shear strengths, and only the numerical difference exists. Under weak shear strength, the stress reaches the platform value after short temporary increase, and there is no stress overshoot behavior. Under strong shear strength, the stress first increases rapidly and then decreases to the plateau value. In this process, there is an overshoot peak. In addition, we further studied the structural properties of comb polymers under start-up shear. Under weak shear strength, the main chain of comb polymer has only slight deformation and orientation and the branched-chain is not basically stretched. Under strong shear strength, the main chain of comb polymer is strongly stretched, but the branch chain still has no obvious change. The results show that compared with the main chain of comb polymer, the branched chain is slightly stretched under start-up shear, which indicates that the influence of branched chain on the rheological behavior of non-entangled comb polymer is weak, so that the properties of comb polymer under start-up shear are similar to those of linear polymer. The simulation results in this paper will help to understand the macroscopic mechanical properties and microstructural changes of comb polymer systems, which are of great significance for designing new polymer materials with desired properties.关键词：Comb polymer;Molecular dynamics;Start-up shear
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发布时间：2024-10-08
Research Article
- 摘要：The functional thin films have great application potential in the field of optoelectronic device, fuel cells, energy storage cells, gas separation, microelectronics and biomedicine, thus becoming the research focus of academia and industry. Understanding the mechanism of morphology evolution, controlling the crystallization properties and phase separation structure are critical in improving device performance. However, in most cases, traditional morphology characterization techniques, such as transmission electron microscopy (TEM) and atomic force microscopy (AFM), failed to describe the morphology and phase separation structure of blend films due to the limited resolution. The emergence of advanced X-ray and Neutron scattering techniques can solve this problem well, allowing us to deeply understand the structure-performance correlations and providing constructive instructions to optimize device performance. For example, grazing incidence wide-angle X-ray scattering (GIWAXS) can be used to characterize crystallization behavior, and provide more detailed crystallization information, such as crystallinity, crystal size, crystal orientation and molecular packing. Grazing incidence small-angle X-ray scattering (GISAXS), small angle neutron scattering (SANS), and resonant soft X-ray scattering (RSoXS) are complementary methods for characterizing the multiscale phase separation structures, and providing the information of phase separation size, aggregates size, interfacial molecular orientation and roughness. Meanwhile, in situ GIWAXS and GISAXS techniques can be used to characterize the morphology evolution process from the precursor solution to thin film, which is of great significance to understand the formation mechanism of non-equilibrium morphology and realize controllable regulation of morphology. Here, we systematically summarize the most important characterization techniques, such as GIWAXS, GISAXS, SANS, RSoXS, and in situ GIWAXS/GISAXS, from two aspects: basic principle and application. In the application section, we take some classical cases to show how to characterize morphology and how to analyze data in a rational way. This summary is convenient for chemists and material scientists to quickly understand the principles and functions of various morphology characterization techniques, and provide instructions on how to choose proper method to study thin film morphology.关键词：Thin film photovoltaic;Scattering technique;Micro-nano structure;Crystallization characteristics;Phase separation structure
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发布时间：2024-10-08
Review (Special Topic: Techniques of Polymer Characterization)
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