Photosensitizers, aromatic

The chemical pathways leading to acid generation for both direct irradiation and photosensitization (both electron transfer and triplet mechanisms) are complex and at present not fully characterized. Radicals, cations, and radical cations aH have been proposed as reactive intermediates, with the latter two species beHeved to be sources of the photogenerated acid (Fig. 20) (53). In the case of electron-transfer photosensitization, aromatic radical cations (generated from the photosensitizer) are beHeved to be a proton source as weU (54). 

TSUDA AND oiKAWA Triplet States of Photosensitive Aromatic Azides 425... 

They are crystalline resins with TJs in excess of 140°C and melting points of around 320°C. Their heat deflection temperature can be increased to near their melting point by incorporating glass filler. They have excellent solvent resistance and stability at 200°C and can be heated to near 300°C for short periods with no serious effect on their properties. Like other resins with the photosensitive aromatic backbone, they are not suitable for extended use outdoors. 

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