Structure and properties of mono-, di-, tri-, and multiblock segmented copolymers with diamide hard segments

Well-defined segmented block copolymers were studied as the number and position of hard segments in the chain was varied. The hard segments were diamides of uniform length (A), and the synthesized copolymers were mono-, di-, tri- or multiblock using the soft segment (B), poly(tetramethylene oxide), with a molecular weight of 2 900 g mol−1 and extended with terephthalate groups to reach a maximum of 20 000 g mol−1. The diamide segments in the chain displayed very high crystallinities and a ribbon-like structure with high aspect ratio. The copolymer without hard segments was a semi-solid. For the materials with one diamide unit in the chain, the modulus was high but the yield and fracture strengths low. When two or more diamide units were used, both the modulus and values for the yield and fracture strengths were high.