Facile in situ preparation of high-performance epoxy vitrimer from renewable resources and its application in nondestructive recyclable carbon fiber composite

Conventional thermosets are built by nonrenewable fossil resources and are arduous to be reprocessed, recycled, and reshaped due to their permanent covalent cross-linking, and their flammability makes them unsafe during use. Here, for the first time, we synthesized a novel Schiff base precursor from abundant and renewable lignin derivative vanillin and produced malleable thermosets (Schiff base covalent adaptable networks (CANs)) combining high performance, super-rapid reprocessability, excellent monomer recovery, and arbitrary permanent shape changeability as well as outstanding fire resistance. The Schiff base CANs exhibited high glass transition temperatures of ∼178 °C, tensile strength of ∼69 MPa, tensile modulus of ∼1925 MPa, excellent flame retardancy with UL-94 V0 rating and V1 rating, and high LOI of ∼30%. Meanwhile, three Schiff base CANs showed high malleability with the activation energy of the bond exchange of 49–81 kJ mol–1 and could be reprocessed in 2–10 min at 180 °C. These Schiff base CAN...

Robust, Fire-Safe, Monomer-Recovery, Highly Malleable Thermosets from Renewable Bioresources

Flammability feature of combustible polymer foam materials often causes massive casualties and property loss, and it is therefore urgent to develop a green and high-efficiency strategy that can reduce or avoid the fire blaze disasters. Here, an extremely simple water-based coating approach is proposed to prepare mechanically flexible, super-hydrophobic and flame-retardant polyurethane (PU) foam nanocomposites with high-efficiency fire warning response. The hybrid ammonium polyphosphate (APP)/graphene oxide (GO) is decorated onto the PU foam surface via electrostatic interactions followed by surface silane functionalization. Interestingly, the silane and APP molecules present selective distributions on the GO and thus form micro-/nano- rough surface with low water affinity to achieve super-hydrophobicity (e.g. water contact angle of ~158.4°). Meanwhile, such hybrid APP/GO/silane coatings produce synergistic flame resistance for the PU foam materials, which is attributed to the formation of compact and uniform P-Si elements co-covered rGO layer on the foam surface. Further, the hybrid coatings can provide high-efficiency fire warning response under complicated conditions, e.g. flame detection response time of only ~2.0 s and excellent fire early warning time in pre-combustion (e.g. 11.2 s at 300 °C). Therefore, this work provides new perspectives to design and develop multi-functional coatings for fire safety and prevention applications.

Water-based hybrid coatings toward mechanically flexible, super-hydrophobic and flame-retardant polyurethane foam nanocomposites with high-efficiency and reliable fire alarm response

A novel phosphorus/nitrogen-containing polycarboxylic acid endowing epoxy resin with excellent flame retardance and mechanical properties

Temperature-responsive resistance sensitivity controlled by L-ascorbic acid and silane co-functionalization in flame-retardant GO network for efficient fire early-warning response

New application for aromatic Schiff base: High efficient flame-retardant and anti-dripping action for polyesters

Bioinspired Color Changing Molecular Sensor toward Early Fire Detection Based on Transformation of Phthalonitrile to Phthalocyanine

The practical problems of insufficient mechanical strength, poor processability, tedious synthesis and flammability facing shape memory polymers have limited their further usage in industrial fields, especially in construction and aerospace. A novel and very simple method of ternary polymerization is presented here to prepare multi-functional copolyesters from general poly(ethylene terephthalate) (PET) through the new well-designed third monomer that features pendent phenylacetylene–phenylimide units. The π–π stacking between phenylacetylene groups as a reversible net-point not only endows the copolyesters with good shape memory and self-healability, but also reinforces the interchain interaction, leading to high tensile strength (79.6–89.6 MPa). Interestingly enough, the phenylacetylene can synergistically crosslink with the unsaturated CN group generated from the phenylimide during burning, resulting in excellent flame retardancy. Thermoplastic smart copolyesters can be designed into fire alarms and can also be used for 3D printing. The printed geometries exhibit good shape memory behaviors, which could be deformed into a small size to save space during transportation/storage and allow manufacturing freedom for space applications.

Lin Chen

Papers

New application for aromatic Schiff base: High efficient flame-retardant and anti-dripping action for polyesters

Bioinspired Color Changing Molecular Sensor toward Early Fire Detection Based on Transformation of Phthalonitrile to Phthalocyanine

3D printable robust shape memory PET copolyesters with fire safety via π-stacking and synergistic crosslinking

Semi-aromatic copolyesters with high strength and fire safety via hydrogen bonds and π-π stacking

Tailoring Schiff base cross-linking by cyano group toward excellent flame retardancy, anti-dripping and smoke suppression of PET