Polymerization of Cycloolefins

III. Polysulfone of 1, 3-Cyclohexadiene

Abstract

Copolymerization of 1, 3-cyclohexadiene (1, 3-CHD) with sulfur dioxide was studied. 1, 3-CHD copolymerized with SO₂ without initiator even at-78°C. Copolymers obtained from the heterogeneous copolymerization systems were white powder and soluble in phenols and in SO₂ below about-35°C, on the other hand, copolymers obtained from the homogeneous systems were ivory-like and insoluble in ordinary solvents.
The composition of the copolymers was alternating (1.3-CHD: SO₂=1: 1) and the structural unit consisted of the cyclohexene ring substituted with SO₂ at the 3-and 6-positions.
The initial rate of copolymerization (R_po) showed a maximum value at about-35°C and decreased above this temperature. It was assumed that this dependence of R_po on the temperature was related to the change of miscibility of the components in the copolymerization system and of the solubility of the copolymers at about -35°C. The apparent over-all activation energy of the copolymerization was 4.7 kcal/mole below-40°C. R_po was second order with respect to the initial concentration of 1, 3-CHD and third order with respectto SO₂ at-40°C, but at 0°C, second order with respect to the both components.
The copolymer began to pyrolyze at about 180°C and was also decomposed by aqueous alkali or by liquid ammonia. It was considered from the measurement of X-ray diffraction that polysulfone was partly crystalline.