The solid-state thermal polymerization of bis(p-toluene sulphonate) of 2,4-hexadiyne-1,6-diol. III. An ESR study

Electron spin resonance (ESR) observations of the solid-state thermal polymerization of bis(p-toluene sulphonate) of 2,4-hexadiyne-1, 6-diol at 60°C, 70°C, and 80°C are reported. The weak paramagnetism observed in polycrystalline samples is interpreted in terms of departures of the polymer chain from an equilibrium conformation. Decomposition occurs at 70°C and 80°C during the final phase of polymerization producing additional paramagnetic centers. Lineshape parameters measured during polymerization show changes which we attribute to changes in the delocalization and mobility of the paramagnetic center. We conclude that the nature of paramagnetism in crystalline conjugated diacetylene polymers is a chain defect property characteristic of interband electronic states close to the valence band.