Thermosetting acetylene‐terminated polyphenylquinoxalines

Abstract

SynopsisA series of acetylene-terminated phenylquinoxalihe oligomers have been prepared which cure by addition, without the evolution of volatiles. The synthesis utilized the novel terminal acetylene end-capping reagent, 3-(3,4-diaminophenoxy)phenylacetylene. The end-capped oligomers were soluble (20-30%) in low-boiling organic solvents and exhibited a high degree of flow a t their softening temperatures. Thermal analytical data obtained on the oligomers indicated initial softening in the vicinity of 160°C and a strong polymerization exotherm reaching a maximum a t 274OC. Cured samples (8 hr a t 28OOC) exhibited Tg values of approximately 320OC. Mass spectrometry-thermogravimetric analysis of the polymers demonstrated that no volatiles were emitted during cure, and that decomposition of the resins initiated a t 465°C. Synthetic routes to the acetylene terminated phenylquinoxaline oligomers and the end-capping reagent are discussed as well as the physical properties of the oligomer and cured system.

Thermal cure behavior and pyrolysis of methyl‐tri(phenylethynyl)silane resin

“…Kovar et al 18 and Admur et al 19 have discussed the mechanism of the thermal polymerization of phenylacetylenes with and without radical initiators. In the absence of initiators, in general, the observed polymerizations were predominantly initiated by the thermal homolysis of impurities, including peroxides or hydroperoxides formed due to oxygen, present in the monomer.…”

Mechanism of Step-Growth Thermal Polymerization of Arylacetylene

“…Diyne and enyne linear dimers formed from Glaser and Straus coupling reactions might be produced during the first steps of the thermal reaction (14,15). They were implied as reaction intermediates to explain the formation of aromatic dimers and trimers (14,15). Nevertheless, they were not explicitly identified from reaction products.…”

High-Temperature Polymers and Adhesives

“…40 Even though these materials have not been used as adhesives, they are found to have superior high-temperature resistance and excellent processing characteristics as composites. Other thermoplastic materials such as Udel and Radel (Union Carbide) and PEEK (lCI) are widely used for composite applications; however, very few reports are seen in the adhesive field regarding these materials.…”