Stable star-structured functional polyolefins and methods of making them, the functional polyolefins comprising a polyolefin bound at any position along its chain length to at least one nucleophile-containing silane of the following formula: wherein Y is a di- or trivalent linker group selected from heteroatoms, C1 to C10 alkylenes, and other groups disclosed herein; Nu is a nucleophilic atom or unsaturation group; R5 is selected from hydrogen, and C1 to C10 alkyls, and other groups as disclosed herein; X is a divalent group selected from linear and branched alkylenes and heteroatom-alkylenes, and other groups as disclosed herein; and PO is a polyolefin having a weight average molecular weight of at least 400 g/mole; with the proviso that at least one of R1, R2, and R3 is selected from the same or different functional polyolefin moieties. Star-structured functional polyolefins are useful as filler dispersive additives in tire formulations and processing aids.