The inclusion and polymerization of the diene monomers 2,3-dimethylbutadiene, isoprene, trans-piperylene, trans-2-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, chloroprene, 1,3-cyclohexadiene, 2,3-dimethylbutadiene/isoprene, isoprene/trans-piperylene, and isoprene/butadiene within the tunnels of clathrates formed by tris(o-phenylenedioxy)cyclotriphosphazene have been achieved. The polymerizations were accomplished by Co-60 gamma-irradiation. All the polymers obtained by this technique resulted from 1,4-addition. Specifically, 1,4-trans-poly(dimethylbutadiene), 1,4-trans-poly(isoprene), isotactic 1,4-trans-poly(trans-piperylene), isotactic 1,4-trans-poly(trans-2-methyl-1,3-pentadiene), 1,4-trans-poly(4-methyl-1,3-pentadiene), 1,4-trans-poly(chloroprene), atactic 1,4-poly(cyclohexadiene), 1,4-trans-poly(isoprene/dimethyl-butadiene), 1,4-trans-poly(isoprene/trans-piperylene), and 1,4-trans-poly(isoprene/butadiene) were formed. The stereoregularity is explained in terms of monomer packing arrangements in the tunnels.