Linear diblock (SB) styrene-butadiene block copolymer

linear triblock [ (SB) 2]and star-shaped four-arm triblock [ (SB) 4 ] poly (styrene-block-butadiene-block-styrene) copolymers were respectively dissolved in tetrahydrofuran (THF) and cyclohexane (CH)

and then their intrinsic viscosities were measured.The obtained viscosity radii (Rη) of the polymers in those solvents were calculated by a modified Einstein equation.The radii of gyration (Rg) of the polymers dissolved in each solvent under different temperatures were obtained from static laser light scattering measurements.Due to the similarity between Rη and hydrodynamic radius (Rh)

the characteristic parameter ρ (= Rg/Rh)

which can be used to describe the morphology of a polymer chain in solution

can be calculated by ρ = Rg/Rη.The ρ value of (SB) 4 in THF is 1.51

but is 0.76 in CH

showing flexible chain and hard sphere morphology

respectively.The ρ values of (SB) 2 are 0.97 and 0.81 in THF and CH

which are located in the region of hollow sphere morphology.However

the ρ values of SB are greater than 1

showing flexible chain morphology in both solvents.Therefore

the molecular architecture of a polymer has great influence on the morphology.