TY - JOUR
T1 - Fast char formation induced by POSS confining Co-MOF hollow prisms in epoxy composites with mitigated heat and smoke hazards
AU - Han, Zhengde
AU - Zhang, Wenyuan
AU - Song, Xiaoning
AU - Vahabi, Henri
AU - Pan, Ye Tang
AU - Zhang, Wenchao
AU - Yang, Rongjie
N1 - Publisher Copyright:
© 2023 Elsevier B.V.
PY - 2023/10/15
Y1 - 2023/10/15
N2 - Polyhedral oligomeric silsesquioxanes (POSS) containing transition metals have excellent flame retardant properties. However, the flame retardant obtained by direct coordination of transition metal cobalt (Co) with POSS tends to agglomerate, resulting in unsatisfactory flame retardant efficiency. Herein, a synthetic route was designed to use a water-soluble cobalt-polyvinylpyrrolidone (Co-PVP) complex as the template and cobalt source to first grow cobalt-metal–organic frameworks (Co-MOFs) on its surface, and then an aqueous solution of Na-POSS was used as both a structure-directing agent and an etching agent to load POSS and remove the template synchronously. Finally, a hollow prism with POSS wrapped around the Co-MOF (designated Co-MOF@POSS) was obtained. The hollow structure not only showed an optimized dispersion in the matrix but also exposed more active sites, catalyzing the formation of the carbon layer, and the silica ceramic layer formed by POSS further enhanced the strength of the carbon layer. An excellent flame retardant effect was obtained by adding Co-MOF@POSS to epoxy at 2 wt%. The heat release and smoke release of the epoxy composites were significantly reduced by the synergistic effect of cobalt and silicon, and the addition of Co-MOF@POSS improved the limiting oxygen index to 27.5% and decreased the peak of heat release rate, total heat release, and total smoke production by 34.6%, 16.6% and 23.8%, respectively. This work provides new ideas for the preparation of MOF and POSS-based flame retardants.
AB - Polyhedral oligomeric silsesquioxanes (POSS) containing transition metals have excellent flame retardant properties. However, the flame retardant obtained by direct coordination of transition metal cobalt (Co) with POSS tends to agglomerate, resulting in unsatisfactory flame retardant efficiency. Herein, a synthetic route was designed to use a water-soluble cobalt-polyvinylpyrrolidone (Co-PVP) complex as the template and cobalt source to first grow cobalt-metal–organic frameworks (Co-MOFs) on its surface, and then an aqueous solution of Na-POSS was used as both a structure-directing agent and an etching agent to load POSS and remove the template synchronously. Finally, a hollow prism with POSS wrapped around the Co-MOF (designated Co-MOF@POSS) was obtained. The hollow structure not only showed an optimized dispersion in the matrix but also exposed more active sites, catalyzing the formation of the carbon layer, and the silica ceramic layer formed by POSS further enhanced the strength of the carbon layer. An excellent flame retardant effect was obtained by adding Co-MOF@POSS to epoxy at 2 wt%. The heat release and smoke release of the epoxy composites were significantly reduced by the synergistic effect of cobalt and silicon, and the addition of Co-MOF@POSS improved the limiting oxygen index to 27.5% and decreased the peak of heat release rate, total heat release, and total smoke production by 34.6%, 16.6% and 23.8%, respectively. This work provides new ideas for the preparation of MOF and POSS-based flame retardants.
KW - Epoxy composites
KW - Flame retardant
KW - Hollow structure
KW - Metal-organic framework
KW - POSS
UR - http://www.scopus.com/inward/record.url?scp=85169043681&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2023.145682
DO - 10.1016/j.cej.2023.145682
M3 - Article
AN - SCOPUS:85169043681
SN - 1385-8947
VL - 474
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
M1 - 145682
ER -