Polymerization of 1-methylthio-1-alkynes and polymer properties

Polymerization of 1-methylthio-1-alkynes (MeSC?CR; R = Et, n-Bu, n-C₆H₁₃, and n-C₈H₁₇) was studied by use of transition metal catalysts. A 1 : 2 mixture of MoCl₅ and Ph₃SiH provided polymers having M?_w over 1 × 10⁵ in 30–50% yields from these monomers. The length of the alkyl group hardly affected the polymerization. The monomer, MeSC?C-n-C₆H₁₃, showed low reactivity in homopolymerization, but higher reactivity than that of MeC?C-n-C₅H₁₁ in copolymerization. Poly(1-methylthio-1-alkyne)s were colorless solids, and those with long alkyl pendants (R = n-C₆H₁₃, n-C₈H₁₇) were soluble in various organic solvents. The present polymers were thermally more stable than poly(2-alkyne)s, the corresponding hydrocarbon polymers.