Comb Copolymers with Polystyrene and Polyisoprene Branches: Effect of Block Topology on Film Morphology

Comblike copolymers with randomly distributed polystyrene (PS) and polyisoprene (PI) branches, i.e., PCEVE-<i>g</i>-(PS,PI), were synthesized by the “grafting onto” technique. The comblike copolymers exhibit a low dispersity, high molar masses, and controlled number of branches. Their characteristics and behavior as isolated objects were investigated as solid molecular deposits, using atomic force microscopy (AFM), and in solution, in a good solvent of the polystyrene and polyisoprene branches, using dynamic light scattering (DLS). AFM experiments show isolated uniform molecules that adopt an ovoïdal conformation whose dimensions are found in good agreement with DLS data. The self-organization of the PS, PI comb copolymers was further studied in the solid state as thin films, using SAXS. The results show that PCEVE-<i>g<b>-</b></i>(PS,PI) combs yield lamellar biphasic morphologies that were compared to those observed for PCEVE-<i>g</i>-(PS-<i>b</i>-PI) combs with PS-<i>b</i>-PI diblock branches and those known for linear PS-<i>b</i>-PI of similar weight compositions.