Extended‐chain polyamides: Polyoxamides and polyfumaramides

Abstract

The synthesis of polyamides from short‐chain aliphatic diacids, such as oxalic and fumaric acids, is difficult because of the thermal instability and volatility of the intermediates and side reactions with the polymerization media. A variety of synthetic routes to these polymers has been explored. Several aromatic polyoxamides with high molecular weight were obtained in high yield by an acid chloride vapor‐solvent‐water interfacial process. Polyoxamides of intermediate molecular weight also were obtained by preparation of oligomers from diamines and oxalic diesters and condensing these oligomers further in a thermal polymerization step. Aromatic polyfumaramides and terephthalamidefumaramides were prepared by modified solution procedures in amide solvents. Another route to polyfumaramides was the synthesis of N,N′‐bis(4‐aminophenyl) fumaramide and its use as a diamine with diacid chloride. The 1,4‐phenylene and benzidine polyfumaramides and oxamides have extended‐chain structures in solution in sulfuric, chlorosulfonic, and fluorosulfonic acids. Some of the polymers were soluble enough to yield liquid crystalline solutions. High‐tenacity high‐modulus fibers from poly(1,4‐phenylene fumaramide/terephthalamide)s are described.

Structure and Morphology of Odd Polyoxamides [Nylon 9,2]. A New Example of Hydrogen-Bonding Interactions in Two Different Directions

“…This value suggests equilibrium between polymerization and decomposition rates. In fact, it is well-known that the limited thermal stability of polyoxamides has been a major problem in obtaining high molecular weight polymers …”

Sequential poly(ester amide)s based on glycine, diols, and dicarboxylic acids: Thermal polyesterification versus interfacial polyamidation. Characterization of polymers containing stiff units

“…The polymer, which precipitated during polymerization, was isolated by filtration and successively washed with ethanol, water, ethanol, the polymerization solvent for the organic phase, and ethyl ether before drying in a vacuum desiccator at 60 °C. Polymerizations with oxaloyl dichloride were discarded as a result of the rapid hydrolysis of the diacid chloride 14. Table I summarizes the used solvents and yields of polymerization, whereas intrinsic viscosities are reported in Table II.…”

Oxalamides as a hydrogen bonding motif in thermoplastic elastomers

“…The melting temperatures of aliphatic polyoxalamides (nylon-X,2) 105,109-111,119 and copolyoxalamides (nylon-X,2,X,P) 106,117 are in between 200 and 400 (Figure 2.9a). By increasing the chain length of the diamine (X) or the diacid (P), the melting temperature decreases.…”

“…Furthermore, the insolubility of most polyoxalamides in conventional solvents prevents the formation of high molecular weight polymers in solution polymerization, whereas interfacial polycondensation has not been useful because of the rapid hydrolysis of oxalyl chloride 106,108 .…”

“…Polyoxalamides cannot be easily prepared by regular polymerization techniques as used in the synthesis of polyamides since the melting temperatures are mostly close to their thermal decomposition temperatures [105][106][107] . Melt polycondensation of oxalic acid with diamines is accompanied by thermal degradation of oxalic acid as well as the polymer.…”