Reactive & Functional Polymers最新文献

As humanity faces growing water scarcity in many parts of the world, innovative solutions are imperative to achieve equitable access to safe drinking water for all. Atmospheric water harvesting (AWH) is a highly promising solution to water scarcity, comprising water adsorption directly from air using hydrophilic adsorbents, followed by collection upon desorption. Porous organic polymers exhibit distinct advantages for AWH, including broad tailorability, desirable porous properties, and outstanding chemical and thermal stability. This perspective outlines the current state-of-the-art in porous organic materials for AWH, distinguishing between reticular and amorphous materials, to discern key properties and outline future design principles. We also outline key performance metrics and provide a guide for the characterisation of such porous organic materials for those seeking to enter the field of AWH.

2,5-furandicarboxylic acid is an extremely appealing renewable chemical building block because of its potential to replace the petrochemical and industrially widespread terephthalic acid via the synthesis of poly(alkylene 2,5-furanoate)s (2,5-PAF). The recent interest in its structural isomer, 2,4-furandicarboxylic acid (2,4-FDCA), opened the study of poly(alkylene 2,4-furanoate)s (2,4-PAF). In this work, 2,4-FDCA was polymerized with linear glycols of increasing chain length, via a solvent-free polycondensation reaction, obtaining high molecular weight 2,4-PAF. Namely, poly(trimethylene 2,4-furanoate) (2,4-PTF), poly(pentamethylene 2,4-furanoate) (2,4-PPeF) and poly(hexamethylene 2,4-furanoate) (2,4-PHF). These polyesters were compression molded into films and subjected to NMR, GPC, WAXS, PLOM, TGA and DSC analyses. The functional properties for food packaging applications were evaluated by mechanical and gas permeability tests. 2,4-PAF had tunable mechanical properties, depending on the glycol used, and in some cases, the mechanical behavior of a thermoplastic elastomer and shape recovery after break. In particular, 2,4-PPeF had outstanding gas barrier properties, while DSC analyses on 2,4-PHF showed an endothermic phenomenon attributed to the isotropization of a partially-ordered phase: it was possible to demonstrate that this phase was disrupted during tensile tests and slowly recovered over time, at room temperature. Overall, the results offer new insights into the structure-property relationships of poly(alkylene 2,4-furanoate)s and display their great potential for the production of biobased, monomaterial, easily recyclable and sustainable food packaging.

Incorporating zwitterions into the blood-contacting materials has been demon-strated an effective and convenient strategy to minimize protein adsorption and platelet deposition, but is frequently detrimental to the mechanical properties. Herein a feeding 29.0 mol% sulfobetaine (SB) siloxane poly(carbonate urethane urea) (SSiPCUU) was synthesized and evaluated. Although the equilibrium water uptake ratio was increased to 1.20% markedly depressing the hydrolytic degradation resistance and mechanical properties after the zwitterionic modification, its maximum tensile stress and tear strength in the wet state still kept the highest among all the tested samples because the urea groups created therefrom gave rise to the formation of bifurcating hydrogen bonds making a significant contribution to the mechanical properties alongside the unique ion clusters formed from pendant SB species. As a consequence of zwitterionic incorporation, it exhibited an extremely low friction coefficient indicating an excellent lubricity in a wet environment without any post-treatment. Accordingly, both the nonspecific protein adsorption and platelet adhesion were evidently decreased. Moreover, it also depicted a good transparency. The high lubrication performance is desirable for lessening the damage to human blood vessels and a good transparency is favorable to the visualization of the flow of liquid in the catheter. These results illustrated the great potential of the zwitterionic SSiPCUU used in the preparation of balloon catheters, artificial blood vessels, stent coverings and other blood-contacting medical implants and devices.

Cycloaliphatic epoxy resin exhibits excellent comprehensive properties suitable for application in electrical/electronic materials. However, its combustibility issue is more difficult to be handled in nature than aromatic epoxy resins and has not yet well addressed currently. The synergistic effect of multiple structures is the efficient way to solve this problem. Therefore, a novel cycloaliphatic epoxide monomer containing both imide and phosphate groups was designed via imidization and epoxidation in this study. The epoxide monomer BEMP with high purity was obtained by discussing the epoxidation conditions. Using 4-methyltetrahydrophthalic anhydride (MHHPA) as a hardener, the cured epoxy resin BMEP/MHHPA demonstrated inherently outstanding flame retardancy with a high limited oxygen index (LOI) value of 36.5% and achieved UL-94 V-0 rating. Additionally, BMEP/MHHPA showed a significant reduction of 70.5% in heat release rate (HRR) and 57.7% in total heat release (THR) compared to commercial ERL-4221/MHHPA. The synergistic effect of imide and phosphate groups contributed to strong charring ability and intumescent flame-retardant action, resulting in effectively isolating heat and oxygen, and inhibiting the production of volatile flammable components. This approach provides an efficient method for developing highly fire-safe cycloaliphatic epoxides for use in electrical/electronic applications.

The aerospace industry demands a resin matrix with excellent thermal oxidation resistance for advanced composites. A series of poly(carbosilane arylacetylene)s (PCSAs) resins with high silicon content were synthesized via arylacetylene Grignard reagents with polychlorocarbosilane polycondensation in this study. The cured PCSAs were obtained by heating at 150 °C for 2 h, 170 °C for 2 h, 210 °C for 2 h, and 250 °C for 4 h. The temperature at which PCSAs lose 5% weight (T_d5) is approximately 600 °C under a nitrogen atmosphere. The cured PCSAs do not exhibit a glass transition temperature in the range of 50 °C ∼ 450 °C. The cured PCSAs demonstrate outstanding thermal oxidation resistance, with a T_d5 of approximately 560 °C under the air atmosphere. The cured PCSA with high silicon content can retain up to 75% of its weight when exposed to flowing air for 480 h at 300 °C. The retention of mechanical properties of carbon fiber cloth reinforced PCSAs composites (CF/PCSAs) improves with increasing silicon content after 100 h of thermal aging under flowing air at 300 °C. The increase in silicon content is beneficial for reducing surface cracking of cured resins and preventing internal matrix oxidation. Moreover, cured PCSAs can serve as a precursor to be pyrolyzed at 1500 °C to form β-SiC crystal. These results suggest that PCSAs are suitable as a heat-resistant matrix for advanced composites.

The synthesis and properties of side chain polysiloxane hydroxamic acids have been described. The N-p substituted phenyl hydroxamic acids were synthesized by reacting p - allyloxy benzoyl chloride and acryloyloxy sebacoyl chloride with N-arylhydroxylamines in toluene medium, rendered basic with aqueous suspension of sodium bicarbonate at 0 °C or lower. The synthesized N-phenyl substituted hydroxamic acids were attached to poly(methylhydrosiloxane) via hydrosilylation reaction in the presence of platinum catalyst The polysiloxane hydroxamic acids were characterized by melting point, FT – IR, NMR and Mass spectral techniques. The liquid crystalline behaviour of the side chain polysiloxane hydroxamic acids with allyloxy and acryloylsebacoyloxy spacer have been studied by optical.

polansed microscopy and differential scanning calorimetry. Side chain liquid crystalline polysiloxane hydroxamic acids with allyloxy spacer (N-p substituted phenyl p-[(3-polysiloxane propyloxy) benzo] hydroxamic acids, (PHA – 1 to PHA −4) show nematic phases, while the second series with acryloylsebacoyloxy spacer (N-p-substituted phenyl (3-polysiloxane propanone) octyl carbonyloxy hydroxamic acids, (PHA – 5 to PHA – 8) show nematic as well as smectic phases. The liquid crystalline behaviour of the side chain polysiloxane hydroxamic acids with allyloxy and acrylsebacoyloxy spacer have been studied.

Polydimethylsiloxanes with improved mechanical properties that can be processed by 3D printing are in high demand for scientific and practical applications. In our article, we proposed the synthesis of new PDMS copolymers with urethane and triazole fragments using the CuAAC reaction mechanism, as well as 3D printing with the obtained copolymers. Two types of copolymers, with molecular weights of 3000 and 6000 Da of PDMS block length, were prepared and characterized by GPC, IR spectroscopy, TGA, DSC, TMA, SAXS, and rheological measurements to determine their physicochemical properties. The synthesized copolymers were found to be suitable for processing by extrusion 3D printing. This demonstrated the ability to 3D print macroscale models of varying shapes and complexity. The resulting materials retained their printed shape over time.

Epoxy/carbon fiber composites are widely used as structural materials in the aerospace field. Improving the ablation resistance of epoxy/carbon fiber composites is of great importance for the fabrication of highly integrated structural-thermal protection materials. In this study, a silicon-modified epoxy/carbon fiber composite was prepared by a hyperbranched structural design approach. By taking advantage of the excellent antioxidant properties of the silicone compounds generated by the pyrolysis of hyperbranched silicone structures, a dense char layer is rapidly constructed on the surface of composites. The characterization and thermal pyrolysis behavior of hyperbranched silicone-modified epoxy resins are analyzed. In the simulated aerodynamic environment of a high-speed vehicle (where the heat flow is 160 kW/m²), compared with epoxy/CF composites, the value of the mass loss rate of modified composites underwent a reduction exceeding 80%, accompanied by a 60.3 °C decrease in the maximum back-surface temperature. More significantly, the post-ablation mechanical properties were evaluated through a three-point bending test, revealing that the modified composites retained over 95% of their initial flexural strength and modulus after simulated pneumatic heating. This approach offers a new approach to manufacture structurally simple, integrated structure-thermal protection systems.

Effective uptake of radioactive steam waste in the fission process is of great vital for the safe use of nuclear energy. Nitrogen-rich polyethylenepolyamine provides effective adsorption sites for the capture of iodine, but triethylenediamine (TEDA)-impregnated activated carbon has the disadvantages of easy sublimation, poor safety, and poor regeneration capacity. Herein, we report five polyethylene polyamine-based (PEPA-based) flexible COFs for the first time which were synthesized by Schiff base polymerization reactions with the flexible knot [2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (TPT–3–CHO)] and flexible linkers (PEPA). The PEPA-based flexible COFs possess large surface areas and strong iodine adsorption capacity, which can be reused. With the increase of the linker lengths, their BET-surface areas decreases, but their adsorption of iodine increase. When dispersed in polar organic solvents, the PEPA-based flexible COFs can fluorescently sense iodine through the electron transfer mechanism and the energy transfer mechanism.