Dynamic birefringence and non-linear rheology of diblock copolymer micellar solutions

Abstract

Dynamic viscoelasticity, dynamic birefringence, and non-linear rheology of styrene-ethylenepropylene diblock copolymer, SEP, in isotridecyl isononanoate solution were examined in order to clarify the rheology-structure relationship for block copolymer micellar solutions. SAXS experiments at room temperature indicated formation of the BCC super-lattice of the micelles, composed of S chain core and EP chain corona. The complex strain-optical coefficient, being the complex ratio of birefringence to strain in dynamic measurements, changed its sign with angular frequency, u, and exhibited a very complicated u dependence, indicating that the stress relaxed through several relaxation mechanisms. Assuming the stress-optical rule for each mechanism, the complex shear modulus was separated into three components. The three components could be assigned to the reorientation of corona chains, reorientation of core chains, and deformation of the lattice. Steady shear viscosity, h, showed strong thinning behavior. Shear rate dependence of h and the first normal stress difference were described well with the BKZ constitutive equation composed of the above three mechanisms having different damping parameters.

Dynamic Viscoelasticity and Birefringence of Poly(ionic liquids) in the Vicinity of Glass Transition Zone

“…Rheo-otical method with the simultaneous measurement of stress and birefringence is a useful technique to characterize the molecular origin of stress because birefringence has a strong correlation with the stress. − For example, the stress-optical rule, SOR, holds valid for rubbery materials . The proportionality coefficient, stress-optical coefficient, reflects the molecular origin of the stress.…”

Control of the Orientation of Symmetric Poly(styrene)-block-poly(d,l-lactide) Block Copolymers Using Statistical Copolymers of Dissimilar Composition

“…Because of their nanoscale morphology, block copolymers have been identified as having a range of different potential applications, which include membranes, − antireflective coatings, , organic photovoltaic devices, high density storage media, photonic materials, , and nanolithography . The nanolithography applications in particular, which typically involve the directed self-assembly (DSA) of block copolymer thin films with lithographically prepared physical or chemical templates, have shown exceptional promise for integration into lithographic processes, where it has been used for generation of high density repeating patterns, − as well as reducing the critical dimension/repairing or smoothing the roughness of lithographically printed features.…”