Convenient approaches for the synthesis and characterization of well-defined linear-dendritic diblock copolymers having a definite number of peripheral primary amino groups: Exact control of numbers introduced and dendritic distribution to enhance co-operative effect

Abstract

Efficient and convenient approaches have been developed to prepare a wide array of well-defined linear-dendritic diblock copolymers having a definite number of peripheral primary amino groups by utilizing linear polystyrenes end-functionalized with a definite number of dendritic benzyl bromide and/or benzyl alcohol functionalities as precursory polymers. Various approaches including modified Gabriel synthesis, Michael addition and alkylation reactions have been developed for their synthesis. The resulting primary amine-end-functionalized copolymers always exhibited SEC profiles showing asymmetric long-tailed distributions and their true molar masses were obtained after the acetylation of their peripheral dendritic amino groups with acetyl chloride. All the resulting copolymers possessed well-defined linear-dendritic diblock architectures, with controlled molecular weights. In these polymer series, the molecular weight of linear polystyrene chains remained almost unchanged ( M n ∼ 19.3 kg/mol), while the dendritic blocks increased in both size and molecular weight as the number of peripheral dendritic end-functional groups was increased. The resulting copolymers were fully characterized by elemental, FT-IR, TLC–FID, GPC, 1H and 13C NMR analyses.