SYNTHESIS AND PHYSICAL-PROPERTIES OF N-SUBSTITUTED POLYIMIDES BASED ON IMIDAZOLE

AB-type monomers based on imidazole for the preparation of polyimides were synthesized by carrying out a substitution at the I-position of 2 -amino-4,5-dicyanoimidazole, followed by hydrolysis. Thus, pendant gro ups such as hexyl and 2,4-dinitrophenyl as an aliphatic long chain and an electron-withdrawing group, respectively, were introduced at the 1 -position of the imidazole monomer. A solid-state polymerization was e mployed to prepare the poly (imidazoleimide) s in the form of a film f rom poly (imidazoleamic acid chloride) s by heating up to 180-200-degr ees-C. The carbonyl stretching peaks of the imide ring appear at 1808 (sym) cm-1 and 1756 (antisym) cm-1. The effects of monomer structure o n reactivity and the degree of imidization were investigated by compar ing the viscosity of the resultant polymers and intensity of carbonyl peak at 1808 cm-1. The difference in the hydrolysis rate between polyi mides having short or long aliphatic pendant groups at the 1-position was observed using FT-IR. The inherent viscosity of the N-hexyl polyim ide was 1.26 dL/g in N-methyl pyrrolidinone (NMP) and 0.22 dL/g in the case of N-2,4-dinitrophenyl poly(amic acid) in methanesulfonic acid a t 30-degrees-C. The structural, physical, and material properties of t he polyimides were characterized by infrared, nuclear magnetic resonan ce, luminescence, viscosimetric methods, differential scanning calorim etry, thermogravimetric analysis, optical microscopy, and wide angle x -ray scattering. Solution properties were also investigated by monitor ing the viscosity as a function of time at 30-degrees-C. Luminescence spectroscopy of the poly(1-methyl imidazole imide) and poly(1-methyl i midazoleamic acid) films shows an emission band centered at 535 and 50 5 nm, respectively. Thermal properties are described comparing the wei ght loss and decomposition temperature as a function of the polymer st ructure and the degree of imidization. (C) 1993 John Wiley & Sons, Inc .