The photochromism and photochromic stability of yellow solid solution of 12-molybdenum phosphoric acid in polyvinylalcohol were studied by ESR, XPS, IR and UV-vis spectroscopy. The results show that the solid solution undergoes a photochemical reaction on irradiation with ultraviolet light to form multivalent molybdenum complex and polyvinylalcohol with partial carbonyl groups, accompanied by a color change from yellow to blue. Because of its spiral structure, the polyvinylalcohol with partial carbonyl groups is able to form inclusion complex with the multivalent molybdenum complex and thus increase the photochromic stability. So the above solid solution is an irreversible photochromic mateiral of both theoretical and practical values.

Key words: POLYVINYL ALCOHOL, PHOTOCHROMISM, STABILITY, CLATHRATES, X-RAY DIFFRACTION ANALYSIS, INFRARED SPECTROPHOTOMETRY, ULTRAVIOLET SPECTROPHOTOMETRY