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New investigation of 1‐substituted imidazole derivatives as thermal latent catalysts for epoxy‐phenolic resins
Author(s) -
Wong Fung Fuh,
Chen KunLung,
Lin Chun Min,
Yeh MouYung
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26002
Subject(s) - imidazole , chemistry , catalysis , polymer chemistry , medicinal chemistry , organic chemistry
Novel 1‐substituted imidazole derivatives ( 4 – 10 ) were synthesized by imidazole and the corresponding substituted reagents (chloromethylpivalate, diphenylphosphinicchloride, di‐ tert ‐butyldicarbonate, 1,1′‐oxalylchloride, pyrazine, phneylisocyanat, and p ‐toluensulfonylchloride). Polymerization of diglycidyl ether of bisphenol A (DGEBA) with 1‐substituted imidazole derivatives, two commercial available catalysts (imidazole and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole) and N ‐benzylpyrazinium hexafluoroantimonate were investigated as model reactions of epoxy resin systems with respect to the thermal latency and storage stability of the catalysts. The catalytic activity of 1‐substituted imidazole derivatives 4 – 10 depended on the steric and withdrawing electronic effect of the substitution groups. To characterize the cure activation energy and the viscosity‐storage time, the order of thermally latent activity is 1‐tosylimidazole ( 6 ) > 1,1′‐oxalyldiimidazole ( 8 ) > N ‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) > 1‐tritylimidazole ( 9 ) > N ‐phenyl‐imidazole‐1‐carboxamide ( 5 ) > 3‐(diphenylphosphinoyl)imidazole ( 7 ) > tert ‐butyl‐1 H ‐imidazole‐1‐carboxylate ( 4 ) > 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole (2E4MZ, 2 ) > 1‐[(pivalyloxy)methyl]imidazol ( 10 ) > imidazole ( 1 ). In comparison with commercially available catalysts imidazole ( 1 ) and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole ( 2 ) and a cationic latent catalyst N ‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) as the standard compounds, in addition to 1‐[(pivalyloxy)methyl]imidazole ( 10 ), the 1‐substituted imidazole derivatives ( 4 – 9 ) revealed better thermal latency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007