Tetrahydrofuran and propylene oxide were copolymerized in the presence of the catalyst boron fluoride ethyl ether, and various co-catalysts, such as 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol. Ethylene chloride was used as a solvent and as an internal reference for analytical purposes. Reactions were carried out at 0 °C and at atmospheric pressure. Monomer concentrations were determined by vapor phase chromatography, and copolymer molecular structure analyses were carried out by physical and chemical methods including infrared spectroscopy, vapor pressure osmometry, hydroxyl end-group analysis, and chemical reduction of unsaturated linkages.The homopolymerization of tetrahydrofuran did not take place, whereas that of propylene oxide proceeded at a rapid rate. In the copolymerization of tetrahydrofuran with propylene oxide, the rate of disappearance of tetrahydrofuran was found to be independent of its concentration, but varied directly with the concentration of propylene oxide. Under similar conditions, the rate of disappearance of propylene oxide was found to be (a) proportional to the square of its concentration, and (b) inversely proportional to the concentration of tetrahydrofuran.Reactivity ratios varied between 1.3 and 1.8 for propylene oxide and between 0.1 and 0.6 for tetrahydrofuran. Molecular weights obtained by vapor pressure osmometry ranged between 460 and 740, and those obtained by hydroxyl end-group analysis ranged between 520 and 1 660. Infrared spectra confirmed the presence of hydroxyl groups and ether linkages in the copolymers prepared. Results on terminal unsaturation were negative.
