Journal of Polymer Science最新文献

AB-type monomers enable a more flexible molecular design of polyurethane synthesis than the conventional methods by the polyaddition of diol and di-isocyanate, that is, various side chain structures can be easily integrated on the former. Meanwhile, the impact of the substituent effect has not been clearly investigated on the synthesis and properties of polyurethanes from AB-type monomers despite its fundamental importance. Herein, we developed four new AB-type monomers exhibiting certain substituents to study the above issue. Interestingly, the introduction of a benzene ring to the side chain moiety did not significantly affect the thermal properties of the polyurethane compared with the corresponding polymer having an n-butyl substituent, while that to the main chain moiety drastically changed the reactivity of the monomer and the thermal properties of the resulting polymer. Moreover, a 2-ethylhexyl side chain structure increased the solubility and flexibility of the polyurethane framework while maintaining the high monomer reactivity at the same time, indicating it would work as a useful comonomer to increase the processability of rigid polymers.

Epoxy resins (EP) have significant application value in the industrial sector; however, their flammability and toxic fume emissions during combustion limit their applications. Bio-based flame retardants provide effective flame-retardant properties, primarily owing to their unique molecular compositions and structural features. In this study, a flame retardant (DAVN) is prepared using vanillin, 5-amino-1H-tetrazole, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). When 6 wt.% DAVN is added to the EP, the EP composite exhibits a residual carbon content of 19.9% at 700°C while achieving a limiting oxygen index (LOI) value of 32.6% and the UL-94V-0 standard. Additionally, compared with pure EP, the peak heat release rate (PHRR), total heat output (THR), total smoke production (TSP), and smoke production rate (SPR) decrease by 49.3%, 44.7%, 35.1%, and 35.1%, respectively. These improvements primarily result from the polyphosphates formed from the DAVN decomposition, which promote the carbonization and cross-linking of EP, thus forming a compact carbon layer that suppresses heat and smoke release. Moreover, the formation of gas during combustion dilutes the combustible gases, thereby enhancing flame retardancy. Additionally, DAVN improves the mechanical properties of EP and increases its tensile strength by 7.1%. This study provides a useful reference for the development of high-performance flame-retardant EP composites.

The replacement of non-recyclable multilayer films with high-performance, monolithic polymer films represents a critical goal for a circular economy. This feasibility study investigates melt mastication (MM), a novel processing technique that utilizes flow-induced crystallization (FIC) to enhance the mechanical and barrier properties of high-density polyethylene (HDPE). The MM process, particularly at low shear rates, fundamentally alters the semicrystalline morphology, increasing the bulk crystallinity to an exceptional level of 85%. This unique, non-spherulitic, granular morphology results in a dramatic enhancement of mechanical properties, with a greater than 240% increase in elastic modulus and a 340% increase in tensile strength compared to conventional controls. A detailed, multi-scale characterization using thermal analysis (DSC), X-ray scattering (WAXS/SAXS), solid-state NMR, and electron microscopy (SEM) elucidates the structure responsible for this performance. The resulting morphology is a direct product of an FIC pathway that occurs above the nominal melting temperature. While the oxygen barrier performance shows a complex dependence on the interplay between crystalline and amorphous structures, the most highly crystalline MM films demonstrate promising properties. This work establishes MM as a powerful pathway for upcycling commodity polymers and provides a model for understanding how chaotic shear can create non-equilibrium structures with enhanced performance.

Smart adsorption material toward both anionic and cationic dyes have been reported rarely, despite bright prospects in dye adsorption. Polyampholyte is a potential ideal candidate. PAAD (copolymer of acrylamide, acrylic acid and [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) is a novel thermo-responsive hydrogel based on polyampholyte, whereas inferior mechanical properties induce fracture during the adsorption process. Herein, we designed a novel cellulose-based crosslinker, which constructs both a robust backbone and reconfigurable physical entanglements in the PAAD-matrix hydrogel to improve the fracture strength and elongation by nearly 195.70% and 360.65%. Meanwhile, the physical entangle is disentangled during deformation and could be re-entangled after deformation, endowing the hydrogel with efficient energy dissipation, fatigue resistance and self-recovery ability, while the highly rigid chemically crosslinked backbone could maintain the shape of the hydrogel under stress. Moreover, the hydrogel can be used as a controllable adsorption material toward both cationic and anionic dyes, which could greatly increase adsorption capacity after reaching UCST due to its temperature-sensitive characteristics.

Thermoplastic elastomers (TPEs) have recently emerged as a class of promising precursors of ordered mesoporous carbons (OMCs) due to their low cost and broad availability. Despite understanding their reaction-induced morphological changes, the fundamental pyrolysis kinetics of crosslinked TPEs remain poorly understood. In this study, we systematically investigate the pyrolysis behavior and pore formation mechanisms of sulfonated polystyrene-block-polybutadiene-block-polystyrene (SBS) using thermogravimetric analysis coupled with mass spectrometry (TGA-MS), nitrogen physisorption measurements, and model-free kinetic analysis. TGA-MS results reveal a multi-stage thermal decomposition process characterized by distinct thermal transitions and volatile product evolution. Nitrogen physisorption measurements demonstrate the development of mesoporosity and surface area with increasing pyrolysis temperature, identifying critical thermal windows for mesopore formation. Furthermore, kinetic modeling of the pyrolysis process was used to determine the apparent activation energies for the cleavage of aromatic and unsaturated moieties. These findings can provide important mechanistic insights for material and process design for producing OMCs via direct pyrolysis of commercially available TPEs.

Novel heterobimetallic polymer-metal complexes (PMCs) based on ferrocenyl-containing polysiloxanes with pyridine-2,6-dicarboxamide moieties coordinated with Co^II, Ni^II, and Fe^II metallocenters (M-PyPMFSs), as well as ferrocenyl-containing polysiloxanes with 2,2′-bipyridine-4,4′-dicarboxamide fragments coordinated with Co^II and Ni^II metallocenters (M-BipyP(MFS-co-DMS)s) were obtained by polymerization, polycondensation, and complexation reactions. The structure of the ferrocenyl-containing polymer ligands and their PMCs was confirmed by NMR, FTIR, UV–Vis, and EDX spectroscopies. The electrochemical behavior of the PMCs was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Both M-PyPMFSs and M-BipyP(MFS-co-DMS)s exhibit multiredox activity due to the presence of two redox active metallocenters (ferrocenyl group and Ni^II, Co^II, or Fe^II coordination cross-links). A comprehensive analysis of the redox properties is conducted to establish the influence of both metallocenter and polymer ligand in the M-PyPMFSs—M-BipyP(MFS-co-DMS)s series. Thus, M-PyPMFSs demonstrate enhanced multiredox performance over M-BipyP(MFS-co-DMS)s, as evidenced by their two intensive well-resolved redox processes in CVs at E _1/2 ≈ 0.1 V (Fc/Fc⁺ couple) and at E _1/2 ≈ 0.8–1.1 V (Co^II/Co^III and Ni^II/Ni^III couples). However, M-BipyP(MFS-co-DMS)s exhibit up to three redox transitions (Fc/Fc⁺, M^II/M^III, and Bipy^•−/Bipy mixed with M^I/M^II). These polymer-metal complexes enable new applications as multiredox silicone materials in polymer engineering, especially for (opto)electronic, adaptive electrochromic, and stimuli-responsive devices.

The CoFe₂O₄@reduced graphite oxide (rGO) was prepared by a one-step solvothermal reaction, and then the Ag nanoparticles were deposited on the CoFe₂O₄@rGO by a green mild reduction reaction to form the novel Ag-CoFe₂O₄@rGO filler, followed by the modification of Ag-CoFe₂O₄@rGO using hexadecyltrimethoxysilane to form the novel H-Ag-CoFe₂O₄@rGO filler. The homogeneous distribution of the Ag-CoFe₂O₄@rGO and H-Ag-CoFe₂O₄@rGO fillers in the polar PVDF plastic polymer and nonpolar SBS elastomer copolymer, respectively, to form the corresponding composites was proved by SEM. The polar crystal content of the PVDF matrix in the Ag-CoFe₂O₄@rGO(10 wt.%)/PVDF composite was 36.13%, while the corresponding value for pure PVDF was 29.38%. The dielectric constant at 1000 Hz of Ag-CoFe₂O₄@rGO(10 wt.%)/PVDF and H-Ag-CoFe₂O₄@rGO(10 wt.%)/SBS composites was 15.54 and 2.78, respectively, while the corresponding values for pure PVDF and pure SBS were 8.39 and 2.05, respectively. Additionally, although both pure PVDF and pure SBS were non-magnetic, the magnetization values of Ag-CoFe₂O₄@rGO(10 wt.%)/PVDF and H-Ag-CoFe₂O₄@rGO(10 wt.%)/SBS composites were 0.83 emu/g and 0.47 emu/g, respectively, at 50,000 Oe. The as-prepared Ag-CoFe₂O₄@rGO/PVDF and H-Ag-CoFe₂O₄@rGO/SBS composites should have the potential for different applications including dielectric capacitors, dielectric elastomers, sensors, EMI shielding, and so on.

In this study, a novel polyamide (PA)/SiO₂/gelatin (GL) in situ hybrid material (PA-Si-GL) was successfully prepared at room temperature by introducing amphoteric biomass, GL, as a reaction substrate into benzoxazine-isocyanide chemistry (BIC)/sol–gel reaction system. The systematic characterization of PA-Si-GL's chemical structure and fundamental properties was implemented subsequently. The in situ integration of GL with diverse N,O-containing segments (amide, phenol OH, and SiOSi) present in PA/SiO₂ fraction could strengthen the affinity between PA-Si-GL and Hg²⁺/dyes. PA-Si-GL's binding for Hg²⁺ was reasonably utilized to realize the probing of this highly poisonous heavy metal. With PA-Si-GL as the active modifier, the modified glassy carbon electrode (GCE) (termed as PA-Si-GL/GCE) exhibited a specific enrichment-enhanced electrochemical response toward Hg²⁺, with a detection limit as low as 2.8 × 10⁻¹⁰ mol/L. Concurrently, PA-Si-GL can remove both anionic (Congo red [CR]) and cationic (methylene blue [MB]) dyes from contaminant water. The maximum adsorption capacities of PA-Si-GL for CR/MB reached 680.1/1001.3 mg/g (298 K), respectively. Mechanistic studies regarding Hg²⁺ probing and dyes adsorption by PA-Si-GL were carried out by the combination of experimental comparison and chemical calculation.