Synthesis and characterization of hydroxy‐terminated poly(alkylene oxides) by condensation polymerization of diols

Acid‐catalysed condensation polymerization of 1,6‐hexanediol, 1,8‐octanediol and 1,10‐decanediol was carried out in the 150–190°C temperature range in the presence of sulphuric acid or Nafion‐H resin, and the polymerizations were monitored by size‐exclusion chromatography. The products were identified as hydroxy‐terminated poly(alkylene oxides) by 1 H and 13 C NMR and IR spectroscopy. The polymers were obtained in 66–81% yield from both catalysts in the polymerizations of 1,8‐octanediol and 1,10‐decanediol. With 1,6‐hexanediol the polymer yields were 30 and 42‐56% in the presence of Nafion and sulphuric acid, respectively. These low yields were due to the formation of oxepane as confirmed by gas chromatographic analysis of volatile condensation products. Vapour pressure osmometry showed the number‐average molecular weight of polymers to be in the range 700‐2400, depending on the reaction time and temperature. The hydroxy functionality of the poly(alkylene oxides) was 2.0 as determined by vapour pressure osmometry and 1 H NMR spectroscopy.