Abstract:Bisphenol A diglycidyl ether (BADGE)
is cured thermally using phthalic
acid anhydride (PhA) or hexahydrophthalic anhydride (HHPA) as hardener
in the presence of different protected N-heterocyclic
carbenes (NHCs), from which the catalytically active NHCs are generated
in situ upon heating. It is found that the curing reactions proceed
in a well-defined manner, delivering highly cross-linked, high-T
g-thermosets using low catalyst loadings (0.1–1
mol % of NHC precursor). The polymerizations can be conducted unde… Show more
“…Epoxides have recently also been copolymerized with anhydrides, using thermally generated NHCs as curing agents . Bisphenol A diglycidylether (BADGE) and hexahydrophthalic anhydride (HHPA) were converted this way to duroplastic material, importantly without the need for protective reaction conditions.…”
“…Epoxides have recently also been copolymerized with anhydrides, using thermally generated NHCs as curing agents . Bisphenol A diglycidylether (BADGE) and hexahydrophthalic anhydride (HHPA) were converted this way to duroplastic material, importantly without the need for protective reaction conditions.…”
“…These catalysts can initiate polymerization under external impetus such as thermal or photo irradiation. Various kinds of latent catalysts are used in the polymerization reaction such as sulfonium salt [1][2][3][4], phosphonium salt [5], pyrazinium salt [6], N-heterocyclic carbene [7], aminimide [8], and sulfonate [9]. We have previously reported that primary alkylamines intercalated with α-zirconium phosphate (α-ZrP) can serve as latent thermal initiators in the reaction of glycidyl phenyl ether (GPE) [10] and that intercalation compounds of 1,4-diazabicyclo(2,2,2)octane (DABCO) and 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU) with α-ZrP: α-ZrP·DABCO and α-ZrP·DBU show good performance as latent thermal catalysts in the reaction of GPE with hexahydro-4-methylphthalic anhydride (MHHPA) [11].…”
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.
“…[ 10,16,19,20 ] For the synthesis of poly(ε-caprolactam) and poly(ε-caprolactam)-co -poly(lauryllactam) by the action of protected NHCs and their properties, refer to refs. [9 , 13] To obtain melt spun poly-LL-co -poly-ε-CL fi bers, 3 g (75 wt%) of CL, 1 g (25 wt%) of LL, and 5 wt% of 6-Cy-CO 2 were mixed in a mortar inside a glove box.…”
The copolymerization of lauryl lactam (LL) with ε‐caprolactam (ε‐CL) initiated by the latent, CO2‐protected N‐heterocyclic carbene‐based initiators 1,3‐dicyclohexyl‐3,4,5,6‐tetrahydropyrimidinium carboxylate (6‐Cy‐CO2), and 1,3‐dimethyl‐3,4,5,6‐tetrahydropyrimidinium carboxylate (6‐Me‐CO2) has been explored. The temperature‐dependent exchange of the protecting group in 6‐Cy‐CO2 and 6‐Me‐CO2 with 13C‐labeled CO2 is studied to gain knowledge about the onset of CO2 release from the carbene. Under exclusion of moisture, a storable batch containing 75 wt% ε‐CL, 25 wt% LL, and another 5 wt% 6‐Cy‐CO2 can be prepared. This batch is successfully used in the in situ melt spinning of poly(ε‐CL)‐co‐poly(LL)‐based single‐filament fibers.
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