CONFORMATIONAL PROPERTIES OF POLY-P-PHENYLENE-1,3,4-OXADIAZOLE MOLECULES IN SULFURIC-ACID

Hydrodynamic and dynamo-optical properties of samples of poly-p-phenyl ene-1,3,4-oxadiazole (POD) with molecular weights from 4.6 x 10(3) to 100 x 10(3) in dilute solution in 96 and 100% sulphuric acid have been investigated. Molecular-weight dependence of intrinsic viscosity for POD in 96% H2SO4 was established by light scattering and viscometry me thods as [eta]96 = M(w)2BAR(52 + 0.77 x M(w)1/2BAR)-3. Weak charge eff ects were detected in the diffusion phenomenon of POD molecules in 100 % H2SO4. The data on flow birefringence and diffusion-viscometric anal ysis show the absence of aggregation of POD molecules in 100% H2SO4 an d increase in the degree of expansion of the POD molecules in solution with increasing H2SO4 concentration up to 100%. This increase is equi valent to an increase of several times in the Kuhn segment length. The possible causes of this effect are discussed.