Synthesis and Structural Analysis of an H-Shaped Polybutadiene

The synthesis of an H-shaped polybutadiene homopolymer as well as its detailed structural characterization is investigated. Anionic polymerization techniques together with chlorosilane linking agents were used for the production of the material. After each reaction step samples were taken and analyzed by size exclusion chromatography (SEC), membrane osmometry (MO), NMR, and temperature gradient interaction chromatography (TGIC). According to the characterization by SEC, MO, and NMR, the H-polymer showed a high degree of structural uniformity after purification by fractionation, and no significant amounts of differently branched byproducts could be detected. The TGIC analysis however revealed the presence of large amounts of structures, mainly with lower branching degree.We also found that a significant isotope effect exists in the TGIC retention between deuterated and hydrogenous polymers. In our case, where the H-polymer is partially deuterated, the TGIC analysis enabled us to resolve all the side products. Comparison of the different analysis methods indicates that the precise structural analysis of branched model polymers such as the H-polymer requires more sophisticated methods than used in the past.