Transparent, flame‐retarded, self‐healable, mechanically strong polyurethane elastomers: Enabled by the synthesis of phosphorus/nitrogen‐containing oxime chain‐extender

Abstract

Polyurethane (PU) elastomer has been widely used due to its excellent mechanics, acid and alkali resistance, abrasion resistance, and other properties. However, obtaining simultaneous mechanically strong, flame-retarded, transparent, and efficient self-heal ability of PU elastomer is of great challenge due to the structural design. Here, a phosphorus/nitrogen-containing Oxime chain extender (PSK-2) was introduced into the synthesis of PU elastomers to obtain a transparent, flame-retarded, self-healable, mechanically strong PU elastomers. The PU elastomers exhibited high tensile strength of ~23.3 MPa, breaking strain of ~1693%, good flame retardancy with high LOI of ~29.2%, and UL-94 V1 rating with the addition of 4.67 mmol (mass fraction 1.37 wt%) PSK2. Furthermore, the PUPSK2 elastomer material also had good healing ability up to 60% at room temperature and good transparency of 83.7% at 350-800 nm visible.

Dynamic covalent polymers enabled by reversible isocyanate chemistry

“…A phosphorus-containing aldoxime crosslinker was introduced into networks (0.97 wt%) for the development of flame-retarded POU CANs with a high limiting oxygen index (LOI) value of ∼29%. 129 Chen et al 130 exploited a kind of POU CANs synthesized from p -quinone dioxime, HDI trimer, and Jeffamine D230, which possessed photothermal properties resulting from the conjugated structures of quinone dioximes. The surface temperature of POUs could reach 115 °C when irradiated for 35 s with an 808 nm NIR laser.…”

Reducing High-Molecular-Weight Oligomers in Biobased Pentamethylene Diisocyanate Trimers

“…The basic building block of PU is the carbamate group, which is formed through the additional polymerization of isocyanates with diols or polyols . Owing to their excellent wear resistance, toughness, mechanical strength, corrosion resistance, and processability, − they are widely employed in various fields, including coatings, , adhesives, , fibers, , thermoplastics, , thermosetting materials, , biomimetic materials, , and nanocomposites. , Commonly used polyisocyanates include aromatic and aliphatic isocyanates, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI), which are derived from fossil feedstocks. − However, with the increasing global demand for PU, traditional polyisocyanates are facing challenges caused by decreasing fossil resources and increasing environmental pollution. New biobased isocyanates have attracted widespread attention from researchers and industries because of their high biochar content.…”

Mechanical property-enhanced thermally conductive self-healing composites: preparation using designed self-healing matrix phase and hyBNNSs

“…12 Currently, the most commonly used method is to introduce dynamic chemical bonds into the polyurethane structure, such as the introduction of reversible covalent bonds [ e.g. , Se–Se bonds, 13 S–S bonds, 14 D–A (Diels–Alder) reaction bonds, 15 oxime–carbamate bonds, 16 boronic ester bonds, 17 CN bonds, 18 and urea chemistry bonds 19 ] or dynamic non-covalent interactions 20 [ e.g. , hydrogen bonds (H-bonding), 21 π–π stacking, 22 metal–ligand bonds, 23 host–guest interactions, 24 and ionic interactions 25 ].…”