Radical reactions initiated by chelate complexes of transition metals. V. Effect of the system bis‐(–)ephedrine copper(II)chelate/carbon tetrachloride on the degradation and/or crosslinking of polymers

Abstract

AbstractThe reaction system bis‐(–)ephedrine copper(II)chelate/carbon tetrachloride was used as a source of trichloromethyl radicals for degradation and/or crosslinking of various polymers. It was found that this reaction system was little effective in degradation of polystyrene and polyisobutylene and/or crosslinking of polyethylene. The chain scission efficiency for polyisobutylene and polystyrene is of order 10−4 to 10−3 while no detectable quantity of gel was observed in the crosslinking of polyethylene. For the ratio of the rate constant of the reaction between trichloromethyl radicals and polystyrene, kPo1 H, and the rate constant of the reaction between trichloromethyl radicals and chelate, kChel H′ the value kPol H/kChel H = 0.18 was found. Thus trichloromethyl radicals react approximately 5 times more readily with hydrogen atoms of the chelate than with polystyrene. This result may account for the low efficiency of the system chelate/carbon tetrachloride in the degradation and/or crosslinking of polymers.