Radiation effects on poly(1‐chloro‐1‐alkynes)

Abstract The γ‐radiolysis behavior of poly(l‐chloro‐1‐alkynes) \[ [\rlap{‐‐} ({\rm CCI} = {\rm CR}\rlap{‐‐} )_n ;{\rm R} = n ‐ {\rm alkyl}] \] greatly changed with the length of alkyl group and with the presence or absence of oxygen. When γ‐irradiated in air, poly(l‐chloro‐1‐hexyne) (R = n ‐C 4 H 9 ) decomposed to oligomers; its G s value was as large as 5.4. When irradiated in vacuum, this polymer partly gelled. In contrast, poly(l‐chloro‐1‐decyne) (R = n ‐C 8 H 17 ) partly gelled even by irradiation in air. A high‐dose irradiation of this polymer in vacuum resulted in the quantitative formation of a gel. The polymers irradiated in air contained carbonyl and hydroxyl groups, indicating the participation of oxidation reaction. Comparison with their thermolysis leads to a conclusion that these Cl‐containing polyacetylenes are radiation‐sensitive irrespective of their high thermal stability.