SYNTHESIS AND PROPERTIES OF REGULAR STAR POLYBUTADIENES WITH 32 ARMS

A dendrimer carbosilane containing 32 Si-Cl bonds in the perimeter has been prepared and has been used as a coupling agent to prepare 32-arm star polybutadienes. The dilute-solution properties [R(G)2], A2, [eta], and D0 have been measured in one good solvent and in one theta-solvent. The dimensions of the 32-arm star polymers are compared with those of linear polymers at constant molecular weight. It is shown that the 32-arm star polybutadiene has the characteristic properties of a hard-sphere molecule in dilute solution. The equivalent hard-sphere radii calculated from A2, D0 and [eta] are identical and 1. 29 times larger than the root mean-square radius of gyration. The Daoud-Cotton scaling model for stars is also tested.