Crown ethers as new curing agents for epoxy resins

What is it about?

Different crown ethers(4-aminobenzo-15-crown-5(4-aminobenzo-15-C5),1,4,10, 13-tetraoxa-7,16-diazacyclooctadecane(diaza-18-crown-6), tetraazacyclododecane-1,4,7,10-tetraacetic acid (H4DOTA) and tetraazacyclododecane-1,4,7,10-tetraacetamide (H2ODDA)) have been used as curing agent for the BADGE, (n = 0). The maximum enthalpy change for all systems, except that formed by the epoxy resin with H4DOTA, corresponds to a stoichiometric ratio, since from this value the reaction enthalpies decrease when the proportion of epoxy increases. Heteropolymerization reaction occurs in all the crown ethers. Etherification reactions occur at temperatures much lower (30 °C less) than for porphyrin systems studied in which a second signal appears at 300 °C. The etherification is evidenced by a slight shoulder in thermograms for H4DOTA and H2ODDA. The systems BADGE, (n = 0)/4-aminobenzo-15-C5 and BADGE, (n = 0)/diaza-18-crown-6 improve the thermal stability of the epoxy resin in 30 °C approximately while the improvement for BADGE, (n = 0)/H4DOTA and BADGE, (n = 0)/H2DOTA is about 60 °C.

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