Bio-based layered double hydroxide nanocarrier toward fire-retardant epoxy resin with efficiently improved smoke suppression

Aiming to alleviate the low-temperature sublimation of ferrocene toward efficiently smoke-suppression epoxy resin (EP), the ferrocene molecule was inserted into the nanocavity of sulfonated cyclodextrin intercalated layered double hydroxide (LDH-CD) via host-guest chemistry. Adequate characterizations verified the targeted structure with one ferrocene molecule included into one cyclodextrin cavity. The resulting LDH-CD-Ferr formed a more uniform dispersion in EP matrix than LDH-CD. The comparative experiments demonstrated that 6 wt% LDH-CD-Ferr reduced the peak smoke production rate and total smoke production of EP matrix by 43% and 42% respectively due to the effectively shifted working temperature of ferrocene. The insightful mechanism investigation unveiled the condensed-phase behavior associated with higher-quality chars from catalytic charring reaction by retained ferrocene and the dominant vapor-phase behavior involved in the promoted combustion of smoke intermediate (soot). Additionally, 6 wt% LDH-CD-Ferr imparted EP matrix with increased limiting oxygen index (LOI) and reduced peak heat release rate by 5% and 36%. EP/6LDH-CD-Ferr was able to pass V-1 in UL-94 test relative to no rating of its counterparts. Also, in comparison to the simple mixture of LDH-CD and ferrocene, LDH-CD-Ferr presented the superiority in weakening the impact of ferrocene on the thermal stability of EP. In prospective, the host-guest chemistry offered an efficient approach to industrially utilizing ferrocene.