Photochromic polysulfones .2. Photochromic properties of polymeric polysulfone carrying pendant spiropyran and spirooxazine groups

Photochromes, bound to polysulfone via carboxyamide bonds and physically blended in a polymeric matrix, were prepared and their physical and photochromic properties investigated. In order to express the photochromic activity, plasticization is required; this is readily achieved by using the swelling solvent, N-methylpyrrolidone (NMP). The photochromic activity is repressed in the presence of carboxylic groups, and this requires complex blocking of any acidity, e.g., by esterification or amidation. The photochromic activity was expressed in membranes made from functional and blended polysulfones, yet the photoresponsive membranes did not produce a significant electroresponse or, if they did, this decayed rapidly. Obviously, membranes with a much higher degree of covalent binding are needed.