Calculated heats of formation and strength of bonds in poly(naphthylene sulphides), poly(phenylene sulphides), poly(phenylene oxides) and poly(phenylene ketones)

Abstract

Energy of atomization, energy of formation, and the strength of individual bonds were calculated for poly(naphthylene sulphides), poly(phenylene sulphides), poly(phenylene oxides), and poly(phenylene ketones), using the model of interacting bonds. The naphthalene-based polymers exhibit a stable structure resulting from a polycondensation of naphthalene units without participation of sulphur, followed by crosslinking of the linear chains by sulphidic bridges. Introduction of substituents into the aromatic rings of poly(phenylene sulphides) and poly(phenylene oxides) raises the stability of skeletal bonds, but the opposite is true for poly(phenylene ke ketones). The most pronounced enhancement of stability of CS and CO bonds results from either one substituent in position α or two para-positioned substituents.