Synthesis and structural analysis of an H-shaped polybutadiene

The synthesis of an H-shaped polybutadiene homopolymer as well as its detai led structural characterization is investigated. Anionic polymerization tec hniques together with chlorosilane linking agents were used for the product ion of the material. After each reaction step samples were taken and analyz ed by size exclusion chromatography (SEC), membrane osmometry (MO), NMR, an d 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 signific ant amounts of differently branched byproducts could be detected. The TGIC analysis however revealed the presence of large amounts of structures, main ly with lower branching degree. We also found that a significant isotope ef fect exists in the TGIC retention between deuterated and hydrogenous polyme rs. In our case, where the H-polymer is partially deuterated, the TGIC anal ysis enabled us to resolve all the side products. Comparison of the differe nt analysis methods indicates that the precise structural analysis of branc hed model polymers such as the H-polymer requires more sophisticated method s than used in the past.