Nanofiber Production Equipment| Facile scalable fabrication of triazine-basedflexible covalent organic framework fiberfilm with multifunction at roomtemperature

Dalian Institute of Chemical Physics, CAS: Shi Quan & Kou Yan - Room-Temperature Large-Scale Preparation of Flexible Triazine-Based COF Fiber Membranes

With the growing demand for functional materials in energy conversion and electronic device safety, flexible covalent organic framework (COF) membranes have emerged as highly promising functional materials due to their unique molecular structures and self-supporting properties. However, conventional solvothermal methods for COF preparation typically require high temperatures (≥80°C) and prolonged reaction times (≥48 hours), with the resulting products mostly being powders that are difficult to process into desired forms, significantly limiting their practical applications. The key research challenge in this field lies in achieving rapid, mild preparation of COF materials while endowing them with multifunctional characteristics.

Researchers Shi Quan and Kou Yan from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences recently published their latest findings titled "Facile scalable fabrication of triazine-based flexible covalent organic framework fiber film with multifunction at room temperature" in the Journal of Energy Chemistry.The research team developed a self-supporting COF fiber membrane using an "electrospinning + sacrificial template" room-temperature synthesis strategy. This method requires no dehydration or deoxygenation, with reaction times as short as 3 hours (minimum 0.5 hours), capable of producing large-area films up to 20 cm × 30 cm in size, while demonstrating excellent flexibility and patternable processing characteristics.The researchers first prepared polyacrylonitrile (PAN)/2,5-dihydroxyterephthalaldehyde (DHBD) fiber membranes via electrospinning technology. These were then immersed in a solution containing triazine-based monomer (TTA) and catalyst for room-temperature reaction. After removing the PAN template through solvent extraction, COF fiber membranes with hierarchical pore structures were obtained.By adjusting monomer concentration, the membrane's microstructure could be controlled: low TTA concentrations produced rough fibers approximately 300 nm in diameter, while high concentrations generated complex network structures with 50 nm side branches, significantly increasing specific surface area (930.09 m²·g⁻¹) and mechanical strength (tensile strength 4.21 MPa).

Figure 1: Morphology and patterning design of COF fiber membrane

The triazine-based COF membrane's π-π conjugated structure and suitable bandgap (2.01-2.10 eV) enabled excellent photocatalytic hydrogen peroxide (H₂O₂) production under visible light. The triazine rings, as core structures, possess strong UV absorption capacity that promotes photogenerated carrier separation and migration, enhancing charge transfer efficiency.The COF membrane achieved a production rate of 594.72 μmol·g⁻¹·h⁻¹ with outstanding cycling stability (<5% efficiency decrease after three cycles). Its self-supporting membrane structure addresses the challenges of powder catalyst agglomeration and difficult recovery, allowing direct integration into flow reactors or optoelectronic devices while avoiding the loss and secondary pollution common with traditional powders. Seawater sterilization tests showed 100% bacterial inactivation after 3 hours of illumination.

Figure 2: Optical and photocatalytic properties of COF membrane

When used as porous carriers to load n-docosane (C22) forming composite membranes (C22@COF), they cleverly combined the flame-retardant properties of triazine-based materials with the thermal regulation capabilities of phase-change materials. During combustion, the triazine structure releases inert gases to dilute oxygen and forms a carbonized layer to block heat, reducing peak heat release rate (pHRR) by 64.97% compared to pure C22, effectively inhibiting flame spread and melt dripping to meet electronic device requirements for flame-retardant materials.Simultaneously, C22's phase-change characteristics endowed the membrane with stable thermal management capabilities, maintaining >95% enthalpy retention after 500 heating-cooling cycles, effectively controlling temperature fluctuations in electronic devices.

Figure 3: Flame-retardant and thermal management performance of C22@COF

This research marks the first successful room-temperature large-scale preparation of multifunctional, large-area COF fiber membranes, solving the processing difficulties of traditional powder COFs and providing new pathways for applications in photocatalytic reactors and electronic device thermal safety management. It also offers a new strategy for room-temperature rapid synthesis of COF materials on a large scale. By regulating COF pore structures and functional groups, potential applications could expand to energy storage, separation, and other fields.

Article link: https://doi.org/10.1016/j.jechem.2025.04.061