Enhancing char formation of flame retardant epoxy composites: Onigiri-like ZIF-67 modification with carboxymethyl β-cyclodextrin crosslinking

Qianlong Li, Zhengde Han, Xiaoning Song, Ye Tang Pan*, Zhishuai Geng, Henri Vahabi, Vera Realinho, Rongjie Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

To enhance char formation of flame retardant epoxy (EP) composites, carboxymethyl β-cyclodextrin (CM-β-CD) is employed as an etchant for or ZIF-67 derivatives. In the early stage, etching plays a dominant role. The mismatch in size between CM-β-CD opening and ZIF-67 pore leads to the stacking of carboxyl cobalt complexes on the shell. When the reaction time is prolonged, crosslinking occurs between carboxyl and hydroxyl groups. Crosslinked CM-β-CD weakens and eventually stops the etching process. Triethyl phosphate (TEP), an additive to improve flame retardancy, is also absorbed on the shell in this one-pot synthesis. Herin, the synthesis of metal-organic framework (MOF) derivatives can impart multiple functions to MOF. This novel nanohybrid significantly improved flame retardancy of EP composites with only 2.0 wt% loading. The peak heat release rate (pHRR) and total smoke production (TSP) were reduced by 54.8 and 46.9%, respectively. The integrated multi-element system resulted in an expanded and reinforced char layer. This study proposes a simple and precise method for controlling the structure of MOF-carbohydrate hybrids through competition between chemical reactions.

Original languageEnglish
Article number121980
JournalCarbohydrate Polymers
Volume333
DOIs
Publication statusPublished - 1 Jun 2024

Keywords

  • Carboxymethyl β-cyclodextrin
  • Crosslinking
  • Epoxy composites
  • Flame retardant
  • Metal-organic framework

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