Ring‐opening metathesis polymerization of ω‐norbornenyl polystyrene macromonomers and characterization of the corresponding structures

ω‐Norbornenyl polystyrene (PS) macromonomers whose molar masses range from 2700 to 11000 g/mole have been polymerized under living conditions by ring‐opening metathesis, with a Schrock complex as initiator. The samples obtained have been characterized by a multiangle laser light scattering (MLLS) detector connected to the outlet of a size exclusion chromatography (SEC) instrument. The experimental values of the degree of polymerization (D̄P_n) lie in close agreement with the expected ones. The compactness of the various branched species formed, which covers a wide range of segment densities (ρ_S), is found to depend on two factors that are their degree of polymerization and the size of the initial macromonomer. The ratio (g) of the mean‐square radii gyration (<R²_b) of polymacromonomers to those (<R²₁) of linear PS homologues of same molar mass was also determined. Plotting the variation of g vs. the D̄P_n's of polymacromonomers gives an idea of the conformation adopted by these branched structures.