Journal of Polymer Science最新文献

In electrohydrodynamics, the regulation of the morphology and structures of electrospun nanofibers is crucial for tuning the properties of the final product. In the electrospinning process, the uniform and smooth morphology of polyvinylidene fluoride (PVDF) nanofibers can be obtained by controlling experimental parameters, environmental parameter, and system parameters. However, there is inadequate research on the effect of polymer addition on the morphology enhancement of PVDF nanofibers and the underlying mechanisms. In this study, the effects of the polyvinylpyrrolidone (PVP) molecular weight and content on various process parameters (i.e., Taylor cone length, straight fluid jet length, and spray angle) are evaluated. The obtained electrospun PVDF/PVP nanofibers were further characterized by SEM, EDS, FTIR, and XRD. The results indicate that the solution viscosity, which was controlled by varying the molecular weight and content of PVP, was linearly correlated with the process parameters. As the PVP molecular weight and content increased, the nanofiber diameter increased and the nanofiber morphology became smoother. The EDS results revealed that the nanofibers consisted of PVDF encapsulated by PVP. The FTIR and XRD results indicated that hydrogen bonding between PVP and PVDF weakened the crystallization of PVDF, leading to the formation of smooth PVDF/PVP nanofibers.

Due to the lack of effective physical reprocessing or chemical recovery capabilities, thermosetting polymers face long-term post-disposing problems. The introduction of dynamic covalent bonds can effectively combine reprocessing ability with typical robust properties of thermosetting polymer. However, after multiple reprocessing treatments, thermosets often suffer significant decrease in mechanical properties, so the chemical recycling and reuse is crucial and necessary for the sustainable development of thermosetting polymers. Herein, a series of polyesters PβMδVL-TA with mono- or bis-terminal cyclic disulfide bond was first synthesized via esterification between terminal hydroxyl of PβMδVL and carboxyl of thioctic acid (TA). Then, the thermosetting elastomer with both physical reprocessability and chemical recyclability was prepared by simple UV-triggered ring-opening polymerization of cyclic disulfide. By regulating cross-linking sites and the molecular weight of the mono- or bis-PβMδVL-TA, such polyester elastomers exhibit good tensile strength and elasticity with elastic recovery can reach 98% after 10 cycles. Furthermore, the dynamic reaction of disulfide bonds induced by hot pressing and UV light enables multiple reprocessing of cross-linked elastomers. Remarkably, the efficient chemical recycling of the elastomers was achieved to recover pristine βMδVL monomer with 90% yield in the presence of ZnCl₂ as the catalyst at 130°C.

Ferrocenyl-containing Fe(II)-bipyridinedicarboxamide polysiloxane complexes with two redox metal centers were obtained by anionic ring-opening polymerization, polycondensation, and complexation reactions utilizing various Fe^II:Bipy molar ratios of 1:(3–12). The polymer ligand was characterized by liquid-state NMR, FTIR, and gel permeation chromatography (M _n  = 8800). The structure of the polymer-metal complexes (PMCs), that is, the presence of ferrocenyl groups and [Fe^II(Bipy)₃] coordination cross-links with Fe^II–N_Bipy bond formation, was confirmed by solid-state NMR, FTIR, UV–vis, and EDX. The PMCs exhibit multiredox activity showing three redox waves at E _1/2  ≈ −1.3, 0.2, and 1.0 V related to Fc/Fc⁺ couple, [Fe(Bipy)₂]⁺/[Fe^II(Bipy)₃]²⁺, and [Fe(Bipy)₃]²⁺/[Fe(Bipy)₃]³⁺ transformations. The PMCs possess electrochromic properties resulting from the reduction–oxidation of ferrocenyl (Fc/Fc⁺) and [Fe^II(Bipy)₃] fragments and leading to changes in intensity of bands at 628, 542, and 380 nm in the UV–vis spectra (coloring efficiency reaches 13.4 cm²·C⁻¹). The PMCs are flexible, stretchable, and mechanically strong silicone materials with elongation at break, tensile strength, and Young's modulus reaching 110%, 3.5 MPa, and 21.8 MPa, respectively, with self-healing ability at 100°C. The described properties expand applications of PMCs as multiredox materials in polymer engineering for fabrication of (opto)electronic devices and protective coatings with a long service life compared to previously reported multiredox polymers.

The advancement of communication technology has significantly promoted the development of dielectric polymers. However, the quantitative prediction of dielectric constant for rapid material screening is hard due to the low precision of existing theories. In this paper, a new model was developed to calculate the dielectric constants of organic materials through theoretical deduction correlating to the dielectric and polar Hansen solubility parameter (HSP) functions ($�\; ��\; �\epsilon �\; �=�\; �K_z�\; �{\delta }_p^2�\; �+�\; �B_z��$). This model treated the permanent dipole moments as the primary function determining the dielectric constant and the corresponding polar HSP, which was demonstrated to be in good agreement with experimental data and produced reasonable fitting for organic solvents, thermoplastic polymers, and thermoset polymers, yielding R ² of 0.7488, 0.8104, and 0.7450, respectively, and it demonstrated better fitting with R ² of 0.9043 when applied to organic solvents having low hydrogen bonding component ($�\; ��\; �{\delta }_h��$, < 12.5). This new correlation produces the highest accuracy of prediction when compared to the existing models and provides a better mathematical tool to help design and screen dielectric polymers.

Restoring alveolar bone defects in patients with diabetes poses a significant challenge in the treatment of oral disease. This study involved the fabrication of porous composite hydrogel scaffolds composed of photo-crosslinked chitosan/nanohydroxyapatite via extruded 3D printing. Additionally, glucose oxidase (GOx) and catalase (CAT) were immobilized onto the composite scaffold through EDC/NHS covalent cross-linking to develop a novel 3D-printed glucose-sensitive scaffold utilizing an enzyme cascade reaction. The 3D-printed porous composite scaffolds had high drug encapsulation efficiency (91.94% ± 1.69%). After co-immobilization of GOx and CAT on the scaffolds, the activity of GOx was increased due to the ability of CAT to scavenge H₂O₂, which is a by-product of the glucose-catalyzed reaction. The results showed that dual enzyme scaffolds with co-immobilized GOx/CAT produced better swelling behavior than the single immobilized GOx enzyme scaffolds. Meanwhile, with the increase of glucose concentration, the release of Met also increased, indicating that the dual enzyme scaffolds possess favorable glucose sensitivity. Additionally, the dual enzyme-immobilized 3D-printed scaffolds facilitated cell adhesion and proliferation and exhibited good biocompatibility. Finally, in vitro cellular experiments revealed that the scaffolds effectively promoted MC3T3-E1 osteogenic differentiation in a high-glucose environment. This study demonstrates that novel glucose-sensitive 3D-printed composite hydrogel scaffolds based on enzymatic cascade reaction may provide a feasible new strategy to enhance diabetic alveolar bone repair.

The application of sodium alginate (SA) in the field of hydrogels has attracted much attention. However, it remains challenging to fabricate sodium alginate-based biocompatible hydrogels with improved strength, high elasticity, porosity, and extraordinary adhesiveness. Herein, a hydrogel is constructed by SA and a copolymer of acrylic acid (AA) and meth acrylic acid (MAA), was synthesized via a free-radical polymerization (FRP) and reinforced by using dynamic cross-linker (Fe²⁺/Fe³⁺) with their carboxylate groups (COO⁻) like a chelating complex. The XPS validates the presence of dynamic Fe²⁺ (711 eV)/Fe³⁺ (714 eV) ions in the hydrogel scaffold. Porous structure contributes to improving the swelling rate (400%) which assists in drug delivery (80%) applications. The hydrogel has a well-interconnected network with a crossover point (G′ = G″) at 120 Pa with 8.52% strain and various factors viz. frequency temperature and time sweep study affect the gelation. The hydrogel exhibits a substantial surface area (25m²/g), pore depth size up to 350 nm, and height distribution histogram average size of 394 nm. The poly(AA-co-MAA) copolymer found actively targeting breast cancer MDA-MB-231 cells and exhibited biocompatibility against HEK-293 cells and useful in water soluble controlled drug delivery.

In this study, a series of poly(butylene terephthalate-co-2,6-naphthalate) (PBTN) copolymers was synthesized via a one-step polycondensation process. These PBTN copolymers demonstrate excellent thermal stability and semi-crystalline behavior, with the enthalpy of melting values exceeding 17 J g⁻¹. Crystallization kinetics analysis revealed that the copolymers exhibit significantly higher crystallization rates than neat poly(butylene terephthalate) (PBT) and poly(butylene naphthalate) (PBN), making them well-suited for fiber production. The copolymers were melt-spun, followed by a post-drawing process at a ratio of 2.0, to enhance fiber strength. By adjusting the 2,6-naphthalene dicarboxylate (NDC) content, the mechanical properties and crystallinity of the PBTN fibers were fine-tuned. Tensile testing revealed that the copolymer fiber containing 50 mol% NDC, post-drawn at a ratio of 2.0, exhibits superior toughness, with maximum tenacity and elongation values of 3.13 g den⁻¹ and 69.3%, respectively.

Nanomaterials offer great potential in cancer treatment, particularly in drug delivery, where their unique properties allow for targeted therapy, increasing treatment efficacy while minimizing side effects. Dendrimers, with their highly branched structure, are ideal candidates for drug delivery. However, polyamidoamine (PAMAM) dendrimers, despite their versatility, exhibit cytotoxicity. Modifying PAMAM dendrimers with cholesterol through p-nitrophenyl chloroformate (NPC) mediation enhances their biocompatibility and targeting ability, especially toward cancer cells. In this study, PAMAM G3.0 was successfully synthesized and conjugated with cholesterol to form G3C nanogels, with a nanoscale size of 83.8 ± 21.9 nm. The study of cholesterol conjugation revealed that at 25% surface functionalization of G3.0, G3C exhibited stable behavior in PBS buffer for up to 8 days. The system's capacity to load single or dual drugs was also explored, demonstrating controlled drug release for over 96 h. Moreover, cholesterol modification on G3.0 significantly enhanced cell compatibility. The G3C@QU/PTX system exhibited improved targeting toward HeLa cancer cells in vitro compared to healthy fibroblast cells. This research provides a strong foundation for developing nanomaterials for targeted cancer treatment.