Photolysis of poly-α-methylstyrene

✍ Scribed by Stokes, Suzanne ;Fox, R. B.

• Publisher: John Wiley and Sons
• Year: 1962
• Weight: 525 KB
• Volume: 56
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1962.1205616422

✦ Synopsis

Abstract

The photodegradation of thin films of poly‐α‐methylstyrene by near ultraviolet radiation has been studied in vacuum at 27 and 115°C. Changes taking place during photolysis were followed by a determination of monomer formation by ultraviolet spectroscopy, residue molecular weight through a measurement of intrinsic viscosity, and volatile products by mass spectroscopy. Gross features of the photolysis include random chain scission in the polymer with subsequent depolymerization of the radicals formed to yield small amounts of monomer; the kinetic chain length is on the order of 15 in the temperature range studied. Quantum yields at 27°C. for chain scission and monomer formation are 1 × 10^−3^ and 7 × 10^−3^, respectively. At 115°C. the quantum yields are 2 × 10^‐2^ and 0.5. Small quantities of hydrogen, CO~2~, CO, and a number of hydrocarbons were liberated during irradiation. An approximate one‐to‐one correlation between the number of main chain scissions and CO~2~ + CO molecules evolved was found, suggesting the occurrence of chain scission at weak linkages involving oxygen.