Structure and Properties of Mono-, Di-, Tri- and Multiblock Segmented Copolymers with Diamide Hard Segments
Araichimani Arun, Konraad Dullaert, Reinoud J. Gaymans
Macromolecular Chemistry and Physics; Volume 210 Issue 1, 2009, p. 48-59
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.
In the cover picture nanosized crystalline ribbons of a diblock copolymer with aramide hard segments can be seen, as were observed by AFM phase angle analysis (5 mm × 3.9 mm). The polymer chains run perpendicular to the ribbon length.