Evaluation of chain rigidity of poly(diisopropyl fumarate) from light scattering and viscosity in tetrahydrofuran

Abstract

Poly(diisopropyl fumarate) (poly(DiPF)) was prepared by radical polymerization in bulk or in benzene with an azo initiator at 60°C, and fractionated with tetrahydrofuran (THF) or methanol as the solvent and water as the non-solvent. The selected nine fractions with a relatively narrow molecular weight distribution were used for the viscometric, light scattering and gel permeation chromatography experiments. The light scattering and viscosity studies using several kinds of solvents revealed that the intrinsic viscosity of poly(DiPF) changed less sensitively to the nature of the solvent used, in contrast with the second virial coefficient which was strongly dependent on the solvent. The Mark–Houwink–Sakurada equation was determined as follows: [η]=5.18×10−4Mw0.98 in cm3/g in THF at 30°C. The persistence length (q) of poly(DiPF) was evaluated from the viscosity data in THF using the Bohdanecký plot. The q and the molecular weight per unit contour length (ML) were 11 nm and 1340 nm−1, respectively. These values were compared with those for typical semiflexible polymers reported in literature.