Macromolecular Research最新文献

Unconjugated polymer poly(vinylcarbazole) (PVK) was incorporated into poly[{2,5-di(3′,7′-dimethyloctyloxy)-1,4-phenylene-vinylene}-co-{3-(4′-(3″,7″-dimethyloctyloxy)phenyl)-1,4-phenylenevinylene}-co-{3-(3′-(3′,7′-dimethyloctyloxy) phenyl)-1,4-phenylenevinylene}](SY-PPV) as the emissive layer of PLEDs. The unconjugated backbone of PVK effectively restrains the hole transport property of SY-PPV, which is advantaged to realize better charge-transport balance. Subsequently, the blue-lighting polymer poly[(9,9-dioctyl-2,7-fluorene)-co-(dibenzothiophene -S,S-dioxide)](SO10), which has a deep highest occupied molecular orbital, was employed as the hole-blocking layer to further balance the charge transportation of the emissive device. The SO10 can effectively restrict the hole carrier entering into cathode interface, which is instrumental in avoiding exction quenching on the cathode interface. Through optimizing device structure, a maximum luminous efficiency of 13.52 cd A⁻¹ was realized, which is achieved 120% improvement of that of the pristine SY-PPV as emissive layer. These results indicate that incorporating unconjugated polymer and hole-blocking layer is an efficient method to adjust charge-transport balance of hole-type emissive materials.

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Wound infection causes wound chronicity as the presence of pathogens prolong wound healing time. Endotoxins lipopolysaccharides (LPS) are released from Gram-negative bacteria when they are lysed by host phagocytic cells during an immune response. These endotoxins in wounds are shown to be one of the causes of delayed wound healing. The porous activated carbon (AC) can act as an important absorptive material for the elimination of bacterial toxins, which makes it an attractive biomaterial for infected wounds. NCC is also reported to facilitate cell adhesion, proliferation, and migrations. Previously, our laboratory has shown that chitosan (CS) reinforced with Kenaf nanocrystalline celluloses (NCC) possesses vastly improved mechanical properties. This study explores the potential of incorporating AC into NCC-CS hydrogel (AC/NCC), with the aim of eliminating bacteria toxins in wounds as well as the acceleration of wound healing. The AC/NCC hydrogel was characterized in terms of rheological properties, swelling behaviour, fourier transform infrared spectroscopy as well as zeta potential. Then the AC/NCC hydrogel dressings were evaluated in vitro using a cytotoxicity study and toxin removal assay. The results showed that hydrogels exhibit desirable rheological properties with homogenous activated carbon particles. The hydrogels exhibit low cytotoxicity towards the human fibroblast and keratinocytes cells. The hydrogel can remove up to 85% of endotoxins when treated with 0.1 EU/mL of LPS. In summary, this study has shown that AC/NCC hydrogel has a vast potential as an antitoxin dressing for infected chronic wounds.

Graphical Abstract

AC/NCC hydrogel dressing eliminates endotoxin from infected wounds and accelerates wound healing

Three-armed poly(styrene sulfonate) derivatives (PSS-T) was synthesized by atom transfer radical polymerization (ATRP) and used as dopants for the preparation of star-shaped PEDOT:PSS-T composites. From their loosed packing structure, reduced graphene oxide (rGO) was well doped into the PEDOT:PSS-T composites resulted in improved dispersion properties and enhanced electrical performance. The cyclic stability of supercapacitors using PEDOT:PSS-T/rGO composites showed 95.5% capacitance retention after 10,000 charge/discharge cycles which is superior than its devices using of commercial PEDOT:PSS/rGO composites.

Graphical abstract

The structure of star-shaped PEDOT:PSS-T composite and its excellent capacitance stability.

In this paper, rhodamine 6G and carborane were used as raw materials, and four fluorescent polymers were prepared by one-pot method, namely L100-55 fluorescent polymer (L100-55-B), EPO polymer (EPO-B), RS polymer (RS) and RL polymer (RL). The problem of poor water solubility of carborane was solved and the biocompatibility of rhodamine 6G-nido-carborane was improved. By simulating the release of polymers in different gastrointestinal environments, it was found that the release rate of drugs in the four coating materials was slow and controllable, with good bioavailability. Affected by the properties of the resin, L100-55 and EPO coating had the best release effect in the gastrointestinal tract. In the zeta potential test, the absolute potential values of L100-55-B and EPO-B are stable, both up to 30 mV. Transmission electron microscopy revealed that the drug was uniformly dispersed in the drug carrier material and wrapped into nanospheres with particle sizes below 500 nm. Hela cells were imaged in different acidic environments, and the results showed that the polymer had good affinity with target cells and was closely connected to target cells, indicating good biocompatibility and targeting of the polymer. This design not only solves the bioavailability problem of rhodamine 6G-nido-carborane, but also has a good fluorescence targeting effect.

Graphical abstract

Rhodamine 6G-nido-carborane coated by four eudragits, L100-55, EPO, RS, and RL, are released in the gastrointestinal environment. Cell imaging under a microscope shows that L100-55-B and EPO-B have a strong affinity for Hela cells. Four coating pathways, the released rhodamine 6G-nido-carborane targets tumor cells and exerts inhibitory effects.

1. The bioavailability and water solubility of carborane derivatives have been improved.

2. Rhodamine 6G is used to make the complex visible in vivo, which is convenient for monitoring the drug distribution.

3. Acrylic resin coating can change drug release performance.

4. Hela cell imaging experiments display excellent cellular permeability.

Developing a novel approach for the administration of catechin that ensures sustained bioactivity, even at low doses, is crucial. In this regard, hydrogels were synthesized by polyion complexation of carboxymethyl cellulose (CMC) and chitosan (CS) grafted with epigallocatechin gallate (EGCG-g-CS), which can maintain enduring antioxidant activity. We initially synthesized grafted chitosan with various grafting ratios using a free-radical grafting method. Polyionic complexes were formed by ionic bonding of the amino groups in EGCG-g-CS with the carboxyl groups in CMC. After lyophilization, a hydrogel with a porous structure was obtained. Scanning electron microscopy (SEM), thermogravimetric differential thermal analysis (TG–DTA), and Fourier transform infrared (FT-IR) analyses of the gel structures were conducted. The swelling properties and porosity of the hydrogels were affected by the grafting ratio. The hydrogel gradually released EGCG under low pH conditions owing to chitosan solubilization, resulting in hydrogel disintegration. Additionally, the hydrogels demonstrated cell adhesion and viability. This study suggests that bio-based materials have potential as pH-dependent catechin-releasing materials.

Graphical Abstract

Preparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose

The purpose of this study was to characterize the biological activity of konjac glucomannan (KGM) according to its molecular weight change. KGM-degrading bacterial strain, N3 was isolated from soil and named Bacillus aerophilus following 16S rDNA sequencing and homology analysis. KGMase, a thermophilic konjac glucomannan-degrading enzyme, was partially purified by treating the culture supernatant of strain B. aerophilus N3 with 50% ammonium sulfate followed by rigorous heating at 75 °C for 30 min. The molecular weight (MW) of KGMase was determined to be approximately 41,000 by silver staining following sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). The biochemical properties stipulated that KGMase is optimally active at 45 °C and pH 6.5 which shows the high temperature and pH stability of KGMase. Manno-oligosaccharides (MOs) derived from the hydrolysis of KGM by KGMase showed a concentration-dependent increase in tyrosinase activity. MOs are bioactive compounds derived from the hydrolysis of KGM by the thermophilic KGMase of B. aerophilus and the outcomes of our study demonstrated that MOs will be suitable for application in the cosmetics industry.

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The polymer was engineered and synthesized for the fabrication of perovskite solar cells (PSCs). Pyrazine-based polymer is used as a hole transport material (HTM) in PSCs. Pyrazine is suitable for major transport, such as affording high hole mobility and intermolecular enhancement, and has the advantage of being inexpensive. Remarkable results are achieved by polymerizing a pyrazine-based material (PzTBr) composed of thiophene moiety with a short alkyl group on both sides and a BDT-based material (BDTEH) to yield BDTEH–PzTBr. Dopant-free processed PSCs fabricated with BDTEH–PzTBr exhibited a PCE of 13.2% for green solvent and 15.9% for chloroform solvent. Therefore, the pyrazine-based polymer is an appropriate strategy to synthesize and explore as an HTM in PSCs.

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A donor–acceptor (D–A)-conjugated polymer BDTEH–PzTBr was designed and successfully used as a hole transport material in perovskite solar cells. Due to the advantage of the molecular structure, and uniform morphology, the BDTEH–PzTBr-based device achieved a good power conversion efficiency of over 15.9%. High performance is achieved using easy synthesis processes and inexpensive materials.

In this study, the impact of two compatibilizers, ethylene terpolymer (C1) and maleic anhydride grafted polyethylene (C2), on the mechanical, thermal, and tribological properties of 30% glass-fiber-reinforced polyketone (PK) and polyketone/polyamide 6 (PK/PA-6) blend composites was investigated. In the case of 30% glass-fiber-reinforced PK composites, the mechanical test results showed that C2 significantly improves the impact resistance (over 48.8%) and elongation at break (over 13.3%) values due to the enhanced compatibility between glass fibers and the PK matrix, attributed to the maleic anhydride functionality. The tensile and flexural properties of the 30% glass-fiber-reinforced PK/PA-6 blend composites were determined to be between the values of pure PK/GF30 and PA-6/GF30 composites, which were its constituent components. Notably, these blend composites displayed higher impact resistance (19.6 kJ/m²) and elongation at break (4.86%) values than the pure PK/GF30 and PA-6/GF30 composites. The SEM images suggested that C2 creates a better interface between glass fibers and the matrix, resulting in a more cohesive structure. Differential scanning calorimeter analysis revealed two distinct glass transition temperatures, indicating the existence of two phases, and reflecting the immiscibility of the two polymers. Tribological studies showed that the friction coefficients and specific wear rates of PK/PA-6/GF30 composites were improved by increasing PK segment. The PK-25/PA6-50/GF30-C2 sample exhibited a friction coefficient of 0.341 μ and a specific wear rate of 1.15 10^¯6 mm³/Nm. Overall, the C2 proved to be a more suitable compatibilizer than C1, offering valuable insights for tailoring high-performance materials with enhanced properties.

Graphical Abstract

The influence of two compatibilizers, ethylene terpolymer (C1) and maleic anhydride grafted polyethylene (C2), on the mechanical, thermal, and tribological properties of 30% glass-fiber-reinforced polyketone and polyketone/polyamide 6 blend composites was investigated. Based on, mechanical, microscopic, thermal, and tribological results, the C2 was found to be a more suitable compatibilizer than C1 for improving the interface between glass fibers and the matrix

The luminescent properties of conjugated copolymers could be harmed due to thermo-oxidative degradation, limiting their applications. To overcome these problems, incorporating flexible and stable polymers, such as elastomers, is a simple and advantageous approach to obtaining luminescent, flexible, and thermo-resistant films. Thin films based on blends of a luminescent thiophene/fluorene copolymer (PTPF) and two elastomers, nitrile rubber (NBR) and natural rubber (NR) were prepared by a straightforward method, and thermal degradation tests were carried out at different temperatures. Oxidized structures in the PTPF chains can be observed using FTIR, and up to 330 °C for NR and to 395 °C for NBR, no significant changes were observable, however, over these temperatures, the blends also lost their luminescent properties. The characterization of the films at increasing degradation stages points to possible mechanisms associated with the degradation processes suggesting a strategy to guarantee incremented thermal protection to the conjugated material, maintaining its structural and optical properties at higher temperatures than ambient temperature, making these flexible-luminescent films interesting for applications in which the thermal resistance is a key factor to consider.

Graphical abstract

Thermal degradation study and obtention of thermo-resistant luminescent films based on blends of thiophene/fluorene copolymer and nitrile or natural rubber

To prepare a high-stability flexible sensor for body motion monitoring, a conductive warp-knitted fabric (CWKF) with a two-bar tricot structure coated with polyaniline(PANI) was prepared by in situ polymerization, and then a waterborne polyurethane-coated conductive warp-knitted fabric (WPU/CWKF) was prepared using a simple dip-and-dry method. The structure and properties of both CWKF and WPU/CWKF were analyzed, their strain-resistance sensing properties were investigated, and their application in body motion monitoring was discussed. The results indicate that conductive treatment of in situ polymerization can give the polyester warp-knitted fabric good electrical conductivity, with a resistivity of approximately 5 Ω cm. After coating with WPU, the resistivity of the WPU/CKWF increased to approximately 40 Ω cm. Both CKWF and WPU/CKWF showed good strain-resistance sensing performance, but CWKF was more sensitive than WPU/CKWF, whereas WPU/CKWF was more stable than CWKF. Both the CWKF and WPU/CKWF sensors could monitor body motion in real time. Similar to their base materials, the CWKF sensor demonstrated a higher sensitivity for human movement monitoring, whereas the WPU/CKWF sensor exhibited higher stability.

Graphic abstract

Conductive warp-knitted fabric (CWKF) with a two-bar tricot warp-knitted structure coated with polyaniline (PANI) was prepared by in situ polymerisation. After repeated reciprocal stretching, the structure of the PANI conductive layer on the CWKF surface broke down and its conductivity changed, especially under large strains. CWKF sensors enable real-time human motion monitoring with high sensitivity