Étude par rayons X de copolymères téléchéliques butadiène acide méthacrylique

The telechelic polybutadiene–methacrylic acid copolymer (Hycar CTB) containing 2 mole percent acid and neutralized (5–100%) by alkali ions, Na+, K+, and Cs+, has been studied by small‐angle x‐ray scattering. Salt groups form clusters, and the average value of the radii of gyration is approximately 8 Å; this value seems to be independent of the nature of the cation and the degree of neutralization. The existence of a low‐angle maximum in the scattering intensity gives evidence of a mean distance of 80 Å between clusters in the fully neutralized sample. This distance increases slightly with a decreasing degree of neutralization. A more precise analysis of the small‐angle scattering curve gives further information on the cluster structure: the ionic groups may form small bilayer disks while the polymer chains maintain a regular distance of 80 Å between the disks.