Reactive & Functional Polymers最新文献

Liquid crystal polyesters (LCPs) have been employed in various applications, however, their sustainability of the replacement of petroleum-based materials by biomass resources remains a challenge. In particular, using low-cost, readily available bio-based monomers to synthesize LCPs is rarely explored. Herein, vanillic acid and ferulic acid as easily accessible plant-derived phenolic acids are used to prepare bio-based LCPs. Liquid crystal behaviors of the as-prepared LCPs can be observed through a polarized optical microscope, and their polymerization kinetics are studied by thin-film polymerization technique to reveal the relationship between the copolymerization composition and liquid crystal (LC) behaviors. The formation of LC for the as-prepared LCPs can be promoted by the increase of vanillic acid composition but inhibited by the increased ferulic acid composition. The prepared bio-based LCPs show high thermal stability with high glass transition temperatures of over 80 °C and high decomposition temperature of about 300 °C. This work develops two available bio-based monomers for preparing LCPs, showing a good promise in sustainability.

The separation efficiency of pressure-driven filtration membranes is primarily dictated by the membrane pore size. Membranes with larger pores typically demonstrate high flux but low or zero rejection when it comes to separating small molecules. In protein separation, ultrafiltration (UF) membranes with pore sizes smaller than the molecular dimensions of target proteins are commonly used for size rejection. Taking inspiration from the separation mechanism of nanofiltration (NF) membranes, we hypothesize that introducing charged groups into membranes of appropriate pore sizes could significantly enhance the electrical interaction between membrane charges and protein charges. This enhancement, occurring at the nanoscale distance when protein molecules approach or pass through charged nanoscale membrane channels, may enable the rejection of proteins substantially smaller than the pore size. Using membranes with relatively large pore sizes could lead to an increase in flux. To test this hypothesis, we conducted experiments involving the modification of polyvinylidene fluoride (PVDF) membranes with suitable pore sizes, using polyamidoamine (PAMAM) dendrimers to introduce negative charges to the membranes. The performance of the PVDF membranes and the modified membranes were investigated in the separation of whey proteins. To evaluate the contribution of steric and electrical hindrance to the solute separation, filtration experiments were performed using polyethylene oxide (PEO) and polyacrylic acid (PAA). The membranes were characterized using techniques such as attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results indicate that the modification enhances the rejection efficiency of whey proteins. The whey protein rejection and permeate flux for PVDF membranes were 58.9% and 15.3 LMH, respectively. Following alkaline treatment or PAMAM-G3.5 dendrimer modification, the whey protein rejection increased to 97.3% and 98.8%, respectively. However, alkaline treatment and PAMAM-G3.5 dendrimer modification resulted in a reduction of permeate flux to 5.6 LMH and 2.3 LMH, respectively. This suggests that increasing membrane charge effectively enhances the separation ability of filtration membranes in charged macromolecule separation.

At present, gauze compression and hemostatic powder are commonly used in first aid to stop bleeding. However, the hemostatic effect of gauze compression is poor, and the hemostatic powder is easy to block blood vessels and causes thrombosis. Therefore, developing hemostatic materials with rapid hemostatic function and biosafety remains a challenge. In this article, a double layer hemostatic dressing based on silicone rubber (SR) was prepared. Among them, sponge layer was modified with polydopamine (PDA), and connected to the hydrophilic polymer polyvinylpyrrolidone (PVP) by strong hydrogen bonding. The synergistic synergy of the blood cell affinity of the catechol group and the water absorption of sponge enhanced the hemostatic ability. For the SR layer, ZnO was grown in situ by hydrothermal method as an antimicrobial layer (SRZ). SRZ/PDA-PVP dressing has good mechanical properties, antibacterial properties, coagulation ability and excellent biocompatibility, providing a new idea for the development of hemostatic materials.

With the enhancement of sustainable development concepts and environmental protection awareness, replacing fossil resources with biomass to prepare unsaturated polyester resins is an essential approach to achieve green chemistry. In this study, a bio-based unsaturated polyester (ERM) was synthesized using epoxidized soybean oil and castor oil acid as raw materials. The reinforced modification of two fast-growing woods, Cunninghamia lanceolata (Chinese fir) and Pinus sylvestris var. mongolica (Pine), was investigated. The structure and molecular weight of the polyester at various stages were detected through infrared spectroscopy, proton nuclear magnetic resonance, and size exclusion chromatography. It was found that compared to the original wood, the density of the modified Cunninghamia lanceolata (Chinese fir) and Pinus sylvestris var. mongolica (Pine) increased from 0.36 g/cm³ and 0.45 g/cm³ to 0.9 g/cm³ and 0.78 g/cm³, respectively. Their compressive strength increased from 30.1 MPa and 32.1 MPa to 73.9 MPa and 73.8 MPa, respectively. The water absorption rate decreased from 167.3% and 103.8% to 16.86% and 16.59%, respectively, and thermal stability also showed a significant improvement.

Polymer brushes have proven to have great potential in oil-water separation but it remains a long-standing challenge to improve their operational stability and service endurance. In this work, we sequentially grafted polydimethylsiloxane (PDMS) and poly (N-isopropylacrylamide) (PNIPAM) brushes on the cotton fabric to prepare a durable and self-reparing oil-water separation film (Co@PDMS/PNIPAM). The grafting of liquid PDMS brushes significantly improved the antifouling performance through its lubricating effect thereby improving the durability. The hydrophilic and thermoresponsive PNIPAM was synthesized through a surface-initiated atom transfer radical polymerization (SI-ARGET ATRP). Co@PDMS/PNIPAM shows high flux in various oily water and bio-solution. More remarkably, Co@PDMS/PNIPAM exhibited intelligent self-repairing characteristics, and this further enhances its stability and service endurance in the application of oil-water separation. The results provide pathways to the preparation of antifouling and durable membranes in the application of water treatment, and resource recovery.

Hybrid coating based on hyper-branched polyurethane and elemental sulfur was synthesized by in-situ polycondensation and urethane reaction. The effect of Sulfur in the hydrogen bonding, thermo-mechanical properties and surface morphology of HBPU-Urea-Sulfur hybrid coating at 2 wt% concentration was notable objective of this work. Deconvolution studies confirmed that more hydrogen bonding interaction happened in HBPU-Urea coating. HBPU-Urea coating indicated better young's modulus and tensile strength compared to HBPU-Urea-Sulfur hybrid coating. Interestingly, the elongation percentage increased from 12% for HBPU-Urea to 18% for HBPU-Urea-Sulfur hybrid coating. Thermal stability of the coatings was examined by thermogravimetric analysis (TGA) depicted a 10 °C decrease in thermal stability for 2 wt% sulfur filled hybrid coating. Dynamic mechanical thermal analyzer (DMTA) analysis showed lower glass transition temperature and crosslinking density after addition of sulfur nanoparticles. The HBPU-Urea-Sulfur hybrid coating displays a smooth surface because the size of the sulfur nanoparticles is reduced, leading to uniform dispersion and achieve good compatibility. The HBPU-Urea-Sulfur hybrid coating possess superior antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antibacterial activity of coating is dependent on the presence of sulfur in the coating.

Superhydrophobic materials can solve the problem of oil pollution in water resources. In this paper, superhydrophobic PDMS-SiO₂ with macro-micro-nano multi-level structures was prepared by impregnation method. The superhydrophobic PDMS-SiO₂ material has good physical and chemical stability, and retains its superhydrophobicity after sandpaper abrasion, tape peeling, water immersion, acid or alkali immersion, and high temperature baking. The superhydrophobic PDMS-SiO₂ material has a high oil-water separation efficiency, with the highest oil-water separation efficiency reaching more than 99%, and the oil-water separation efficiency of different oils all exceeding 96%. The preparation of superhydrophobic PDMS-SiO₂ material is simple, inexpensive and environmentally friendly, which can achieve fast and large-area preparation, with good engineering application prospects.

Bone defects are one of the main causes of disability worldwide. Due to the disadvantages associated with autografts, the latest advances have been focused on tissue regeneration approaches that use injectable hydrogels or 3D printed hydrogel-based structures that could refill appropriately the bone gap area without the need for external fixatives, leading to bone formation in the long term. Injectable hydrogels could be applied in extrusion-based 3D printing as inks; in this sense, double-crosslinking hydrogels appear as ideal candidates. In this work, injectable and printable double crosslinkable hydrogels based on oxidized xanthan gum (XGox) and methacrylate polyaspartylhydrazide (PAHy-MA) were produced. The formation of dynamic hydrazone bonds, occurring between aldehyde groups on the polysaccharide backbone and hydrazine moieties of PAHy-MA, induced an instant gelation, conferring, also, injectability and self-healing properties to the hydrogels. The presence of methacrylic moieties on the synthetic polymer allowed further crosslinking upon UV irradiation that stabilized the hydrogel shape and mitigated its susceptibility to hydrolytic degradation. Obtained hydrogels showed pseudoplastic behaviour and good recovery of viscoelastic properties over time. The physicochemical and rheological characterization highlighted increased stability and higher viscoelastic moduli after photo-crosslinking. The hydrogels also showed good printability, cytocompatibility and the early formation of a bone-like matrix when osteosarcoma-derived cells (MG-63) were cultured in the scaffolds for 21 days, with an increased collagen I deposition, mineralization and the expression of characteristic osteogenic markers.

This research examines the influence of relative humidity and a model salt concentration present in the electrospinning process on the diameter of nanofibers composed of hydrophilic polymers by modifying relative humidity and the salt concentration in the polymer solution, we aim to better understand the mechanisms controlling the modulation of nanofiber diameter.

A mathematical model was established using a central composite design (CCD)-response surface methodology (RSM). It was validated by statistical tests and compared with experimental data. The model accurately represents the specific behavior and diameter of each polymer in relation to relative humidity and salt concentration, and is capable of predicting fiber diameter. Thus, it was found that there is no significant interaction between environmental parameters and added salts causing alterations in the diameter of the fibers produced, except for polyethylene oxide (PEO). At high values of both humidity and salt concentration, a synergy between the factors causes a decrease in fiber diameter.

Despite great advances in bactericidal therapy, it is still hard to achieve satisfactory therapeutic effects using the single antibacterial modality nowadays, especially the emergence of drug-resistant bacteria. To address such challenge, a light-induced synergistic therapeutic platform was facilely constructed by incorporating sodium nitroprusside (SNP) into a biocompatible ionic covalent organic framework (COF), denoted as TD-COF, to combat the bacteria infection. Upon 638 nm laser irradiation, the positive charged therapeutic agents (TD-COF-SNP) with strong affinity to the negatively charged bacterial membrane could realize the photothermal-driven cascaded multimodal synergistic treatments, in which the local high temperature could not only induce the controllable generation of nitric oxide (NO), but also significantly accelerate the formation of reactive oxygen species (ROS) via the photodynamic therapy (PDT), destroying the pathogen structure, and killing pathogenic bacteria. Meanwhile, both the in vitro and in vivo assay revealed the synergistic NO/PTT/PDT/cationic triggered by laser irradiation was also highly effective for the treatment of infected wounds caused by bacteria. This work paves an avenue for the delicately design of COF-based solid state therapeutic agents toward bacteria infection treatment.