Dilute solution properties of a polybenzimidazole

• Published in: Journal of polymer science. Polymer physics edition 1980-08, Vol.18 (8), p.1673-1683
• Main Authors: Kojima, Takakazu, Yokota, Rikio, Kochi, Masakatsu, Kambe, Hirotaro
• Format: Article
• Language: English
• ISSN: 0098-1273; 1542-9385
• DOI: 10.1002/pol.1980.180180801

Light scattering and viscometric studies have been carried out on dilute solutions of a polybenzimidazole in N , N ‐dimethylacetamide. The data, which span the molecular weight range 2.9 ≦ 10 −4 M w ≦ 23.3, and the temperature range 290 ≦ T / K ≦343, yield the dependence of the mean‐square radius of gyration 〈 s 2 〉 LS , the second virial coefficient A 2 , and the intrinsic viscosity [η] on molecular weight M w and temperature. The unperturbed mean‐square radius 〈 s 〉 LS was calculated using experimental values of 〈 s 2 〉 LS and A 2 . It was found that excluded volume effects on 〈 s 2 〉 LS are very small. The unperturbed hydrodynamic chain dimension 〈 s 〉 η was estimated by considering draining effects. A small value of the draining parameter was obtained. Analysis of the temperature dependence of A 2 and [eta;] leads to the conclusion that this system approaches a lower theta temperature with increasing temperature. The steric factor σ = 〈 s 〉/〈 s 〉 f , based on the value of 〈 s 〉 f calculated for the polymer chain with free rotation, is nearly unity. Most of these properties can be interpreted in terms of long rotational units within the main chain.