The development of highly efficient radical scavengers remains a substantial challenge in materials chemistry. Here, we report defect-rich Mg(OH)₂ nanosheets (d-Mg(OH)₂), synthesized via rapid nucleation within a colloid mill, as a potent multifunctional antioxidant. Compared to commercial Mg(OH)₂ (c-Mg(OH)₂), d-Mg(OH)₂ demonstrates markedly superior scavenging capabilities against a broad spectrum of radicals, including ·O₂⁻, ·OH, ·NO, DPPH·, and ·Cl. Mechanistic investigations and density functional theory calculations reveal a dual-mode scavenging mechanism: hydrogen atom transfer for ·OH, ·NO, and ·Cl, and electron transfer for ·O₂⁻ and DPPH·, with significantly reduced energy barriers on the defect-rich surface. We further demonstrate the material’s practical efficacy in scavenging intracellular reactive oxygen species and enhancing the thermal stability of polyvinyl chloride. This work establishes a defect-engineering approach to activate earth-abundant hydroxides as high-performance antioxidants, with promising applications in biomedicine and polymer stabilization.

Flexible polyurethane foams (FPUF) are commercially used cushioning materials, but severely suffer from fire risks due to their inherent flammability. Surface coating can localize flame-retardant functionality at the polymer-air interface without altering bulk properties. However, developing a facile nanocoating strategy beyond the layer-by-layer technique for FPUF remains challenging. This work reports novel flame-retardant FPUF@PMo-PPy composites, fabricated by uniformly depositing phosphomolybdic acid (H₃PMo₁₂O₄₀, PMo₁₂) clusters encapsulated within polypyrrole (PPy) via in-situ polymerization onto the FPUF skeleton surface, based on electrostatic interactions. The PMo-PPy coating significantly mitigates the fire hazards of FPUF, exhibiting a maximum reduction of 66.7% in peak heat release rate (pHRR) and 73.5% in peak smoke production rate (pSPR). Notably, the maximum smoke density (D_max) and smoke density at 10 minutes (D_10min) were reduced by 55.7% and 60.8%, respectively, accompanied by lower pyrolysis gas toxicity (HCN and CO). This enhancement is attributed to decomposition products—phosphoric acid and MoO₃—generated from the PMo-PPy coating, which improve the stability and compactness of the char layer. This PMo-PPy nanocoating strategy provides a security assurance for cushioning materials in industrial engineering, ensuring the security of life and property.

Appropriate surface modification or functionalization is prerequisite for the application of inorganic nanoparticles. And surface control between organic and inorganic interface plays an important role in constructing organic–inorganic composites. In-situ polymerization has been extensively studied to improve the compatibility and dispersibility of inorganic nanoparticles, but the polymerized nanoparticles tend to concatenate and form large composites, restricting further applications. Herein, uniform and dense polyacrylic acid (PAA) membranes have been grafted on layered double hydroxide (LDH) nanosheets via an in-situ initiating and terminating radical graft polymerization method. With initiating and terminating on the same particle, the size, morphology and density of grafted PAA onto the surface of LDHs can be controlled by adjusting the ratio of initiated sites to terminated sites, the amount of redox initiator or monomer. As a result, with only 17.33% organic grafting ratio, PAA@LDHs with largely improved compatibility can be monodispersed in polyethylene (PE) and polyvinyl chloride (PVC) matrices, which is determined by a fluorescence microscope technique.

Considerable smoke and toxic volatiles generation has compromised the application of thermoplastic polyurethane (TPU) and caused a great threat to human life. Here, nano-MgFe layered double hydroxide (MgFe-LDH) with uniform particle size was synthesized to reduce smoke density and toxic gases of TPU composites using ammonium polyphosphate (APP) as a flame retardant agent. The results show that the combination of 16 wt.% APP and 4 wt.% MgFe-LDH greatly decreased the smoke density (D_20min and D_{s, max}), smoke production rate (SPR) and heat release rate (HRR) of TPU composites. Furthermore, the MgFe-LDH synergist demonstrated high efficiency in decreasing total volatiled products and toxic volatiles evolved, such as the CO, HCN and isocyanates. The reason was mainly attributed to the chemical reaction between MgFe-LDH and APP, which can promote the compactness of char layers with fine microstructure formed in the decomposition process of MgFe-LDH/APP/TPU composites. The protective char layers could act as barriers between combustion zone and matrix to protect the unburned substrate and promote smoke suppression effect.