Design, Synthesis, and Characterization of Novel Sulfur-Containing Polyacetylenes

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The present project has dealt with the molecular design of novel sulfur-containing- polyacetylenes, the exploitation of methods for synthesizing high molecular weight polymers, and the characterization of the polymers obtained. The results are summarized as follows:1. Synthesis and Properties of Poly(1-n-alkylthio-1-propynes) 1-n-Alkylthio-l-propynes (CH_3CXICSR; R = Me, Et, n-Bu, n-C_6H_<13>, n-C_8H_<17>, and n-C_<10>H_<21>) polymerized in good yields (50 - 80%) in toluene at 80 ﾟC in the presence of MoCl_5-Ph_3SiH(1:2) catalyst. The corresponding W, Nb and Ta catalysts were effective. The product possessed weight-average molecular weights (M^^-___w up to 1x10^5 - 2x10^5, higher than any other sulfur-containing polyacetylenes so far synthesized. Spectroscopic data supported the polymer structure, (-CCH_3=CSR-)_n. Except poly(1-methylthio-1-propyne), the present polymers totally dissolved in common solvents such as toluene and CHCl_3. They were colorless, film-forming, thermally fairly stable in air, electrically insulating, and moderately permeable to gases.2. Polymerization of 1-Methylthio-1-alkynes and Polymer Properties Polymerization of 1-methylthio-1-alkynes (MeSCXICR; R = Et, n-Bu, n-C_6H_<13>, and n-C_8H_<17>) was studied by use of transition metal catalysts. A 1:2 mixture of MoCl_5 and Ph_3SiH provided polymers having M^^-___w over 1x10^5 in 30 - 50% yields from these monomers. The length of the alkyl group hardly affected the polymerization. The monomer, MeSCXIC-n-C_6H_<13>, showed low reactivity in homopolymerization, but higher reactivity than that of MeCXIC-n-C_5H_<11> in copolymerization. Poly(1-methylthio-1-alkynes) were colorless solids, and those with long alkyl pendants (R = n-C_6H_<13>, n-C_8H_<17>) were soluble in various organic solvents. The present polymers were thermally more stable than poly(2-alkynes), the corresponding hydrocarbon polymers.Further, polymerization of several sulfur-containing aromatic acetylenes was examined.