N.N. Glagolev, A.B. Solovyeva, B.I. Zapadinskii,A.V. Kotova, V.A. Barachevskii, P. S. Timashev, V.N. Bagratashvili
Effect of Stabilization of Colored Form of Spiroxazin Photochrome in Polycarbonate Matrix
The impregnation of several thermoplastic polymers (polyethylene, polypropylene, polymethylmethacrylate, polycarbonate) with spiroxazin photochrome (SAO) having a stable unexcited form A, and photoexcited (colored) form B, was performed in supercritical CO2. It is found that, unlike other polimers under study, the supercritical fluid impregnation of polycarbonate (PC) with SAO causes the dramatic stabilization of its colored form B. The bleaching time of SAO in PC after its photoexcitation (900 c) is two orders of magnitude higher than that in polypropylene. Moreover, after supercritical fluid impregnation of PC up to 20 % of SAO is originally formed in colored form, which is not bleachable for 90 days (the whole period of observation), i.e. is extremely stable. The temperature and pressure effects on SAO concentration in different polymer matrixes were measured. At least some part of SAO incorporated into the polymeric matrix forms nanocrystals of ~ 10 ÷ 20 nm size. Possible mechanisms of the observed effect of the colored SAO form stabilization in the polycarbonate matrix are discussed.
Key words: supercritical fluid impregnation, spiroantroxazin, thermoplastic polymers.