O‐Fmoc‐protected 3‐hydroxy‐2‐butenoate derivatives as thermal latent curing agents for thermosetting epoxy resins

Abstract

To improve the stability of epoxy resin‐imidazole compositions, the authors have developed O‐Fmoc‐protected 3‐hydroxy‐2‐butenoate derivatives to generate an imidazole via thermal deprotection and subsequent β‐elimination reactions. The latent curing agents have good compatibility toward epoxy resins. It was found that high reactivity of the agents with epoxy resins is accomplished after their thermal decomposition reaction and that the composition shows long‐term storage stability at room temperature.

Acceleration effects of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene with 2‐methylimidazole‐intercalated α‐zirconium phosphate as a latent thermal initiator in the reaction of glycidyl phenyl ether and hexahydro‐4‐methylphthalic anhydride

“…To avoid the need for high-temperature curing, we examined the enhancement effects of bases with 2MIm intercalated α-ZrP (α-ZrPÁ2MIm) as a potential latent thermal initiator in the acceleration of the reaction with GPE. 24 We first confirmed the storage stability of GPE with bases of . Among those bases, only TBD showed storage stability at 40 C in GPE.…”

“…However, latent curing agents having high reactivity under low temperature and excellent storage stability are under development. To avoid the need for high‐temperature curing, we examined the enhancement effects of bases with 2MIm intercalated α‐ZrP (α‐ZrP∙2MIm) as a potential latent thermal initiator in the acceleration of the reaction with GPE . We first confirmed the storage stability of GPE with bases of 1,1,3,3‐tetramethylguanidine (TMG), 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), 7‐methyl‐1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (MTBD), 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), and 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN).…”

“…We have previously reported that primary alkylamines intercalated with α‐zirconium phosphate (α‐ZrP) may serve as latent thermal initiators in the reaction of glycidyl phenyl ether (GPE) and that intercalation compounds of 1,4‐diazabicyclo[2,2,2]octane (DABCO), 1,8‐diazabicyclo[5,4,0]undec‐7‐ene (DBU), imidazole (Im), 2‐methylimidazole (2MIm), 2‐ethyl‐4‐methylimidazole (2E4MIm), and benzimidazole (Bim) intercalated with α‐ZrP show good performance as latent thermal initiators in the reaction of GPE with hexahydro‐4‐methylphthalic anhydride (MHHPA) . Latent thermal initiators of imidazoles have been developed for curing of epoxy resins . However, latent curing agents having high reactivity under low temperature and excellent storage stability are under development.…”

“…[17][18][19][20][21] Latent thermal initiators of imidazoles have been developed for curing of epoxy resins. [22][23][24][25] However, latent curing agents having high reactivity under low temperature and excellent storage stability are under development. To avoid the need for high-temperature curing, we examined the enhancement effects of bases with 2MIm intercalated α-ZrP (α-ZrPÁ2MIm) as a potential latent thermal initiator in the acceleration of the reaction with GPE.…”

Construction of excellent thermal latent system for the synthesis of networked epoxide polymers by sulfonium salts

“…So far, a wide variety of thermal latent initiators have been developed. The recent examples involve N ‐acylimidazoles, adducts of carbenes with CO 2 , hydroxy amides, derivatives of 4‐aminopyridine, and metal xanthates . Besides, onium salts have been most frequently used because of the easy preparation and the resultant structural diversity that allows appropriate choice of initiator from the libraries .…”