PIN upcycling PET with cobalt MOFs

Post-consumer PET was processed to carbon dots then combined with a cobalt MOF, resulting in a PIN FR for PET. The PET was reacted with ethylene glycol then N,N-dimethylformamide, cobalt nitrate and terephthalic acid to generate carbon quantum dots (CQD) with diameter of 2-5 nm then combined with into a cobalt -PET CQD MOF (metal organic framework). This was tested as a PIN FR at in PET. At 0.4% loading, -22% reduction in pHRR (peak heat release rate) compared to neat PET was achieved, -25% reduction in total smoke release and UL 94 V-2 (3 mm), versus NR for neat PET. Tensile strength and elastic modulus were somewhat reduced, whereas elongation at break was increased. The CQD MOF is considered to accelerate compact char formation in fire and to generate a char structure which inhibits release of smoke and of flammable volatiles.

“Upcycling PET waste into CQDs-MOFs composites: A sustainable strategy for synchronously enhanced flame retardancy and toughened PET”, Y. Wu et al., Polymer Degradation and Stability 252 (2026) 112273, https://doi.org/10.1016/j.polymdegradstab.2026.112273

See also recycling of post-consumer PET to carbon dot PIN FRs, M. Chaohui et al. in pinfa Newsletter 183.