Excluded-Volume Effects on the Mean-Square Radius of Gyration of Oligo- and Polyisobutylenes in Dilute Solution

The mean-square radius of gyration 〈S2〉 was determined from small-angle X-ray scattering and light scattering (LS) measurements for oligo- and polyisobutylenes (PIB) in n-heptane at 25.0 °C in the range of the weight-average degree of polymerization xw from 1.14 × 10 to 2.48 × 103. The model parameters of the helical wormlike (HW) chain for PIB are then determined by analyzing simultaneously the present data for 〈S2〉/xw and the previous data...