Synthesis and Rapid Polymerizations of Aryl- and Alkyl-bis(azetidine-2,4-dione)s to Polymalonamide Elastomers

Abstract

Two new synthetic methodologies for making aryl- and alkyl-bis(azetidine-2,4-dione)s have been accomplished in this study. A new family of N,N'-benzophenonyl bis(azetidine-2,4-dione)s (2) has been successfully synthesized through autoxidation of readily available diphenylmethane bis(azetidine2,4-dione)s (1) in 70-80% yields. In addition, the synthesis of N,N'-alkylene bis(azetidine-2,4-dione)s (3) was accomplished through sensitized photocyclization of N,N'-alkylene bis(N-formyl-2-methylacrylamide)s in anew three-step process from alkylene diamines in overall yields of 63-80%. The prepared bis(azetidine-2,4-dione)s were converted to polymalonamide elastomers in two steps by reacting first with a long-chained polyether diamine of 2000 g center dot mol(-1) molecular weight to form the prepolymers. Subsequently, the prepolymers were melt-polymerized with hexamethylene diamine to produce the final elastomeric polymalonamides. The present study further investigated the reactivities of these aryl- and alkyl-bis(azetidine-2,4-dione)s as well as their elastomeric property differences due to structural variations. The study found that the order of the intermediate's reactivity toward amines is (2) > (1) > (3). This implies that aryl azetidine-2,4-diones, (1) and (2), are more reactive than their aliphatic counterpart (3) toward amines in their ring-opening reactions. Furthermore, the ketone-conjugated aromatic intermediates (2) were found to produce the highest molecular weight polymalonamides in short reaction time and result in polymalonamides with overall superior mechanical properties. For the final elastomeric polymalonamides produced, we found that aromatic polymalonamides were mostly amorphous, but aliphatic elastomeric polymalonamides were fibrous semicrystalline. All of the polymalonamides based on aryl bis(azetidine-2,4-dione)s possess temperature-resistant properties of >350 degrees C. The study indicated that the carbonyl activated bis(azetidine-2,4-dione)s, such as (2), can serve as the best candidate intermediates for making elastomeric polyamides via the rapid reaction injection molding (RIM) process similar to those practiced in polyurethanes

Recyclable Thermosets Based on Dynamic Amidation and Aza-Michael Addition Chemistry

“…The lower thermal stability of these networks compared to that of the conventional polyamide could be attributed to the presence of aliphatic malonamide moiety in the structure. Aliphatic polymalonamides are known possess moderate thermal stability up to ∼300 °C . Reasonably high char yields (18–38%) of the samples supported the cross-linked nature of these networks (Table S2).…”

“…Aliphatic polymalonamides are known possess moderate thermal stability up to ∼300 °C. 61 Reasonably high char yields (18−38%) of the samples supported the cross-linked nature of these networks (Table S2). 62 To explore the recyclability of these networks, the effect of different pH conditions on their degradability was studied.…”

Synthesis of a phosphinated acetoxybenzoic acid and its application in enhancing Tg and flame retardancy of poly(ethylene terephthalate)

“…Experimental data show that using KMnO 4 as an oxidative agent cleavage the acetoxy group, and the product is (1) , not (3) (Path 5', Scheme ). However, (3) can be successfully prepared through Path 5 (Scheme ) according to the oxidative procedure reported by Caruso and Lee and Kuo et al A signal of carboxylic acid at 13.0 ppm (Fig. ), and a carbonyl (C 19 ) signal at 167 ppm (Supporting Information Fig.…”

A strategy for preparing spirobichroman dianhydride from bisphenol A and its resulting polyimide with low dielectric characteristic

“…Therefore, acetic anhydride was used as solvent for the oxidation procedure instead of acetic acid. 27,28 Experimental data show that the methyl groups of OMSBC were transferred to carboxylic acids incompletely under standard pressure. Fig.…”