Radii of Gyration of Ring-Shaped Polystyrenes with High Purity in Dilute Solutions.

Ring polystyrenes (PSs) were synthesized by anionic polymerization technique and purified with preparative size-exclusion chromatography (SEC). Seven ring PSs with their weight-average molecular weight ( M w ) ranging from 17k to 570k were prepared and they were confirmed to have high purities all over 96% by liquid chromatography at the chromatographic critical condition (LCCC) analyses. Their radii of gyration ( R g s) were determined in benzene- d 6 as a good solvent and in cyclohexane- d 12 or cyclohexane- h 12 as Θ solvents by small-angle neutron scattering (SANS) or light scattering (LS). It has been found that R g s of ring polymers are scaled with M w as R g ∝ M w 0.60 in a good solvent and as R g ∝ M w 0.53 in Θ solvents. Moreover it was confirmed that g factors, R g 2 (Ring) / R g 2 (Linear), obtained in Θ solvents are meaningfully larger than theoretically predicted values owing to the topological effect stored in ring molecules.