Ring‐opening polymerization of unsaturated alicyclic compounds

The ring‐opening polymerizations of cyclooctene, cyclododecene, 1,5‐cyclooctadiene, 1,5,9‐cyclododecatriene, 3‐methylcyclooctene, and 3‐phenylcyclooctene have been carried out by using a two‐component catalyst system composed of ethylaluminum dichloride and tungsten hexachloride. NMR and infrared analyses of the respective polymers indicate structures which are consistent with a ring‐cleavage mode of propagation. No evidence for double‐bond shifts or transannular reactions during the polymerizations of 1,5‐cyclooctadiene, 1,5,9‐cyclododecatriene, 3‐methylcyclooctene, and 3‐phenylcyclooctene was found. The polymerizability of substituted, unsaturated, mediumsized alicyclic monomers suggests a convenient method for synthesis of certain perfectly alternating terpolymers. Since polymerizations occurred rapidly with little evolution of heat, it was concluded that entropy is a substantial contributor to the free energy of the ring‐opening polymerization of medium‐sized, unsaturated alicyclic monomers.