Stereoblock vs Stereoblend: Orchestrating Competing Living Coordination Chain Transfer Polymerizations for the One-Pot Production of New Viscoelastic Grades of Poly(4-methyl-1-pentene)

By exerting control over two populations of coexisting cyclopentadienyl, amidinate (CPAM) group 4 metal active species that possess different stereoselectivities for chain growth propagation during the living coordinative chain transfer polymerization (LCCTP) of 4-methyl-1-pentene, controlled production of grades for poly(4-methyl-1-pentene) (PMP) materials that display a tunable range of viscoelastic properties can be achieved in "one-pot" fashion. Analytical and spectroscopic investigations reveal that these differences in viscoelastic properties are associated with formation of atactic/isotactic PMP stereoblends, rather than a stereoblock chain architecture. These results serve to establish the ability of low molar mass atactic PMP to function as an effective property modifier for commercially important isotactic PMP, which in its pure form is highly brittle with low tensile strength. The further outcome of these studies is extension of multistate LCCTP as a tool for expanding the range of accessible grades and properties of polyolefins that can be produced from the limited small set of industrially significant olefins.