Photochemical crosslinking of poly(phenylquinoxalines) in the presence of aromatic azides

Crosslinking of several poly(phenylquinoxalines), induced photochemically in the presence of 2,6-di(4′-azidobenzal)cyclohexanone, has been studied by EPR spectroscopy, using a paramagnetic probe, and by sensitometry. In some poly(phenylquinoxalines) photochemical crosslinking resulting in a loss of solubility has been found to proceed exclusively within a relatively narrow interval of oxygen partial pressure, delimited by lower and upper critical values. This mode of crosslinking is possible because of the chemical structure of the repeat unit.