SYNTHESIS AND CHARACTERIZATION OF RIGID-ROD POLY(P-PHENYLENES)

The polymer PP, which consists of a poly(p-phenylene) backbone with su lfonate eater and dodecyl side groups, is synthesized by a Pd-catalyze d coupling of the 1,3-propanediol diester of 2-dodecyl-5-methyl-1,4-be nzenediboronic acid with -tert-butylbenzenesulfonato)-4-4'-dibromobiph enyl. Polymers with various molar masses are obtained, which are solub le without aggregation in conventional organic solvents. The good solu bility of this rodlike polymer allows the accurate determination of th e molar mass by light scattering, osmometry, and SEC with universal ca libration. The dependence of the intrinsic viscosity [eta] on the mola r mass is determined from both the Mark-Houwink-Sakurada equation and the wormlike chain model. The low value of the persistence length (13 nm) indicates that these polymers are relatively flexible. It is shown that an approximate value of the persistence length, together with th e parameters of the Mark-Houwink-Sakurada equation and the wormlike ch ain model, can be determined using only a single polydisperse sample.