Imidazoles-Intercalated α-Zirconium Phosphate as Latent Thermal Initiators in the Reaction of Glycidyl Phenyl Ether (GPE) and Hexahydro-4-Methylphthalic Anhydride (MHHPA)

Abstract

Abstract:The capabilities of imidazoles-intercalated α-zirconium phosphate (α-ZrP·imidazole): imidazol (α-ZrP·Im), 2-methylimidazole (α-ZrP·2MIm), and 2-ethyl-4-methylimidazole (α-ZrP·2E4MIm) as latent thermal initiators were examined by the copolymerization of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA) with the imidazoles-intercalated α-zirconium phosphate at varying temperatures for one-hour periods. Polymerization was not observed until the reactants were heated to 100 • C or above. Increasing the temperature, polymerization in the presence of α-ZrP·Im, α-ZrP·2MIm, or α-ZrP·2E4MIm proceeded at 140 • C for 1 h with over 90% conversion. The thermal stabilities of α-ZrP·Im, α-ZrP·2MIm, and α-ZrP·2E4MIm in the reaction at 40 • C for 264 h were tested. With α-ZrP·2MIm, the conversion was less than 15% up to 96 h. In the cases of α-ZrP·Im and α-ZrP·2E4MIm, the conversion reached less than 15% at 264 h. The thermal stabilities of α-ZrP·Im, α-ZrP·2MIm, and α-ZrP·2E4MIm at 40 • C were superior to those of the commercially available thermal latent initiators: HX-3088 and HX-3722.

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

“…The conversion for the reactions of GPE with TBD and α‐ZrP∙2MIm over 1 h for the temperature range from 60 °C to 100 °C are presented in Figure . At 80 °C for 1 h, the conversion value was 12% for TBD with α‐ZrP∙2MIm (α‐ZrP∙2MIm‐T), whereas a reaction did not occur in the presence of α‐ZrP∙2MIm alone . At 100 °C, the conversion value drastically increased to 93%, thus confirming the remarkable differences in reactivity as a result of TBD addition.…”

“…In addition of TBD with α‐ZrP∙2MIm, the enhancement effects in the reaction of GPE were observed under heating conditions. We have already reported the reaction of GPE and MHHPA with α‐ZrP·2MIm . Therefore, we investigated the enhancement effects of TBD in the copolymerization of GPE and MHHPA as shown in Scheme .…”

“…The conversion of GPE after 1 h as a function of temperature during reaction with α‐ZrP·2MIm (□) and α‐ZrP·2MIm‐T (Δ).…”

“…Zr(HPO 4 ) 2 ∙H 2 O (CZP‐100) was purchased from Daiichi Kigenso Kagaku Kogyo Co., Ltd. GPE (99%) was purchased from Aldrich Chemical Co., Inc. TBD (98%), MHHPA (98%), and 2,2‐bis(4‐glycidyloxyphenyl)propane (DGEBA, 85%) were purchased from Tokyo Chemical Industries, Co., Ltd. The intercalated compound α ‐ZrP∙2MIm was prepared by a reported method . The chemical composition of α ‐ZrP∙2MIm was Zr(HPO 4 ) 2 ∙0.95C 4 H 6 N 2 ∙0.91H 2 O.…”

“…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 .…”