Studies on structure and viscoelastic properties of diblock and triblock copolymers

Abstract

Characteristic rheological properties of block copolymers related with flow-induced alignment of lamellae for diblock copolymers and effects of bridge, loop, and dangling end conformations of B component in ABA triblock copolymers are reviewed. In the flow-induced alignment phenomena, perpendicular alignment became dominant at high shear rates. Concentration and shear rate regions in which parallel alignment coexists become narrower when the viscosity ratio of components is close to 1. Relationship between elasticity and bridge, loop, dangling end fractions in B phase of sphere-forming ABA tribrock copolymers are examined by using series of model copolymer systems having almost the same microdomain structure but different bridge, loop, dangling end fractions. Elasticity was proportional to the bridge fraction and there was no practical difference between the effects of loop and dangling ends. © 2009 The Society of Rheology, Japan.