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

The γ‐radiolysis behavior of poly(l‐chloro‐1‐alkynes) \[ [{‐‐} ({ CCI} = { CR}{‐‐} )_n ;{ R} = n ‐ { alkyl}] \] 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‐C4H9) decomposed to oligomers; its Gs value was as large as 5.4. When irradiated in vacuum, this polymer partly gelled. In contrast, poly(l‐chloro‐1‐decyne) (R = n‐C8H17) 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.