Electrospinning has been recognized as a simple and versatile method for fabrication of polymer nanofibers. Various polymers that include synthetic, natural, and hybrid materials have been ...successfully electrospun into ultrafine fibers. The inherently high surface to volume ratio of electrospun fibers can enhance cell attachment, drug loading, and mass transfer properties. Drugs ranging from antibiotics and anticancer agents to proteins, DNA, RNA, living cells, and various growth factors have been incorporated into electrospun fibers. This article presents an overview of electrospinning techniques and their application in drug delivery.
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Idiopathic pulmonary arterial hypertension (IPAH) is a progressive vascular disease with high mortality and heritability. Pyroptosis is a novel form of programmed cell death, and it is closely ...associated with IPAH. However, the roles of pyroptosis-related genes (PRGs) in IPAH are still largely unknown. In this study, we identified KIF23 as the most relevant gene for IPAH and pyroptosis, and its expression was significantly increased in pulmonary arterial smooth muscle cells (PASMCs) of IPAH. Besides, the pyroptosis level of PASMCs was also considerably upregulated in IPAH. Knockdown of KIF23 in PASMCs could significantly suppress the PASMCs' pyroptosis and proliferation and then alleviate the increase in pulmonary arterial pressure, right ventricular hypertrophy, and pulmonary vascular resistance in IPAH. KIF23 regulated the expression of Caspase3, NLRP3, and HMGB1, and they were all involved in the PI3K/AKT and MAPK pathways, indicating that PI3K/AKT and MAPK pathways might participate in regulating PASMCs pyroptosis by KIF23. In conclusion, our study suggests that KIF23 may be a new therapeutic target for IPAH, which can alleviate the symptoms of IPAH by inhibiting the pyroptosis and proliferation of PASMCs.
There has been a broad demand for materials with high thermal stability and low dielectric constant in the field of microelectronic devices and communication technology. In this paper, a novel ...fluorinated poly(aryl ether) (FPAE) was prepared by S
N
2 nucleophilic polycondensation. FPAE was demonstrated to possess a favorable dielectric constant of 2.68 at 1 MHz and its dielectric relaxation behavior at various temperatures and frequencies was analyzed. The resin performed excellent thermal stability and heat resistance, with a 5% mass loss temperature of 514 °C and a glass transition temperature of 260 °C. FPAE exhibits high solubility in N, N-dimethyl-formamide, acetone, ethyl acetate and other solvents. Excellent solubility gives FPAE good film formation and processability. The tensile strength and tensile modulus of FPAE were 67.0 MPa and 2.1 GPa, displaying decent mechanical properties. Attributed to the characteristics of the fluorine atoms, FPAE demonstrated a certain hydrophobicity with a water contact angle of 97.9°, as well as satisfactory water absorption (0.17%) and a low surface energy of 21.71 J/mm
2
. These data indicate that FPAE is expected to be used as low-dielectric material in microelectronics and communication technology.
In this study, through blending solutions and followed by electrospinning with hot press technique, poly(aryl ether nitrile ketone), boron nitride and silicon carbide (PEK-CN/BN/SiC) composites were ...fabricated. Functionalized boron nitride (BN) with different sizes by Octadecyltrimethylammonium Bromide (OTAB) and surface-modified silicon carbide (SiC) by γ-(2,3-epoxypropoxy) trimethoxy silane (KH560) were performed as the fillers. The results herein indicate that under the same condition and size of the fillers, the thermal conductivity coefficient (λ) of PEK-CN/BN/SiC composites with incorporating functionalized BN and SiC were both higher than the composites with unfunctionalized BN and SiC. When the condition of the fillers were 20wt% OTAB-BN (12,500 mesh) and 10wt% KH560-SiC, compared with the pure PEK-CN, the glass transition temperature (T
g
) of the composites was increased from 228.1 ℃ to 232.4 ℃. A rise in the thermal conductivity coefficient (λ), from 0.251 W/mK to 0.812 W/mK was observed. Moreover, the thermal stability of PEK-CN/BN/SiC composites was enhanced likewise.
Though phenolphthalein poly(aryl ether ketone) (PEK-C) has gained attention as a special engineering plastic materials by virtue of its good thermal stability and favorable mechanical properties, its ...applications are limited due to its wide PDI during polymerization, which result in poor mechanical properties of PEK-C. In order to investigate the effect of molecular weight and polydispersity index (PDI) on PEK-C, an incremental poor solvent fractionation method was used to fractionate PEK-C. The process produced a series of grades with decreasing molecular weight and PDI. The LCP (linear cloud point) equation was combined with the grading method to find the optimal PEK-C/DMAc/ Non-solvent additives (NSA) system, which can be used to improve the grading efficiency. The obtained results showed that the incremental poor solvent fractionation method with the PEK-C/DMAc/EA system made the molecular weight distributed in the range of 25 ~ 113 kDa, PDI mostly distributed in the range of 1.1 ~ 1.4, and the narrowest PDI to reach 1.13, which could not be obtained through the condensation reaction. Meanwhile, we can also achieve expanded production. By fractionation, the elastic modulus of PEK-C film could be increased by up to 22.6%, elongation at break by up to 38.3%, the fracture strength by up to 38.2%, and impact strength of the sheest by up to 41.2%, while the polymer still maintained good thermal and UV shielding properties. This unique Polymer/Solution/NSA system can yield an effective design strategy for controlling its molecular weight and PDI and improving its mechanical performance.
Graphical abstract
PEK-C (NM01) was fractionated by incremental poor solvent fractionation. Due to the weak pr ecipitation strength of EA to PEK-C, a large number of grades can be obtained by expanding the classification. Through the method of adding precipitant, NM01 was fractionated into two parts with different molecular weights and PDIs. The impact strength of these grades could be improved well.
High molecular weight biobased polyester PEF with satisfactory appearance and faster crystallization rate was obtained by metal zinc powder as an efficiently in-situ catalyst.
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•PEF ...with high Mn (5.40×104gmol−1) and close-to-white appearance was successfully prepared by metal zinc powder as catalyst.•The in-situ catalytic system of zinc metal was efficient and can efficaciously inhibit the coloration of furan-based polyester.•The metal zinc catalytic system acted as nucleating agent and promoted the crystallization rate of PEF, compared with that of PEF-tin.
In pursuit of poly(ethylene 2,5-furandicarboxylate) PEF materials with high molecular weight, satisfactory appearance and faster crystallization rate, its preparation from dimethyl furan-2,5-dicarboxylate (DMFD) with ethylene glycol (EG) in the trace presence of metal zinc was performed via transesterification method. Optimization of the main polymerization parameters enabled Zn-catalyzed PEF to gain high molecular weight (Mn, 5.40×104gmol−1) and low content of diethylene glycol furandicarboxylate unit (DEGF, 2.91%). On the basis of experimental phenomena and high performance liquid chromatography (HPLC), the actual catalytic active species of metal zinc in the polymerization was speculated to be a salt of 2, 5-furandicarboxylate derivative (Zn(II)). The in-stiu catalyst can efficaciously inhibit the influence of by-product FDCA on the color of PEF, which displayed quite better appearance (close to white). Differential Scanning Calorimetry (DSC) showed that the in-stiu catalytic system acted as nucleating agent (NA) and the crystallization half-time (t1/2) of PEFs-Zn was only 1/4 of that of PEF-tin. Additionally, series of high molecular weight furan-based polyesters from DMFD and diols with different methylene (3, 5, 6 and 8) were obtained by zinc powder as in-stiu catalyst, which further evidenced it to be efficiency and universality.
In this study, a series of poly(propylene naphthalate-co-propylene 2,5-thiophenedicarboxylate)s (PPNTFs) copolyesters were synthesized. The properties of these copolyesters were fine-tuned using ...2,5-thiophenedicarboxylic acid (TDCA). For example, poly(propylene naphthalate) (PPN) and poly(propylene 2,5-thiophenedicarboxylate) (PPTF) were semi-crystalline polyesters. However, the melting peaks and melt crystallization peaks in PPNTF23, PPNTF50, and PPNTF76 were not observed because the comonomers destroyed the chains’ regularity. With the increase in the TDCA content, the glass transition temperature gradually decreased. PPN, PPTF, and PPNTFs had excellent thermal stability over 350 °C and good ductility (εb: 130%–320%). High tensile strength (>57 MPa) was observed in PPN, PPNTF23, PPNTF50, and PPNTF76. However, the lowest tensile strength (45.1 MPa) and the highest elongation at break (320%) were observed in PPTF due to the lowest glass transition temperature (36.1 °C). PPTF and PPNTFs exhibited lower processing temperatures than PPN.
•A series of bio-based copolyesters have been successfully synthesized from TDCA, 2,6-NDCA and 1,3-PDO.•The effects of composition on microstructure and properties were investigated.•With the increase of the TDCA content, the glass transition temperature gradually decreases.•PPNTF76 was found to exhibit attractive properties, including good mechanical properties and UV-protection properties.
With the rapid development of 5G technology, low dielectric constant materials present a widespread application prospect in microelectronic devices. Poly (aryl ether) resins have been widely used in ...this field due to their excellent thermal stability, mechanical properties and electrical insulation properties, however, reducing its dielectric constant remains a challenge. In this study, novel phenolphthalein poly (aryl ether ketone) containing isopropyl groups and fluorene groups was successfully synthesized with high molecular weight via SN2 aromatic nucleophilic polycondensation reaction. At lower frequencies ranging from 10 Hz to 1 MHz and higher frequencies from 10 GHz to 42 GHz, the films exhibit the intrinsic dielectric constant in the range of 2.4–2.7. The resin has good thermal stability, mechanical properties and insulation properties. Thus, the functional poly (aryl ether ketone) possesses attractive potential applications in the field of high-performance flexible electronic packaging materials.
The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed ...using X-ray, calorimetric, magnetic, and 57Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time.
Abstract
Aiming at the special needs of transmission lines for repelling birds, this article conducted stress experiments on various bird repellent spices, selected and compounded highly effective ...bird repellent spices; PVDF particles were used as the main carrier material, and dry-wet phase conversion technology was adopted. Supplemented by various functional agents, we have researched and developed a new type of high-efficiency solid bird repellent with slow release, weather resistance and long-term effect. The real-time monitoring results show that the bird repellent has a strong odor and has an obvious repellent effect on birds. It can prevent the birds from approaching the iron tower containing the bird repellent or even returning to the nest. It is environmentally friendly, efficient and long-lasting, easy to install and use, good weather resistance, etc., superior to the existing similar bird repellent products used in the power system, and meets the bird repelling requirements of the power system.
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