SOLID SCINTILLATION PROXIMITY MEMBRANES-I - CHARACTERIZATION OF POLYSULFONE-INORGANIC FLUOR MORPHOLOGIES PRECIPITATED FROM NMP SOLUTIONS

Solid scintillation proximity membranes were prepared by coagulation o f polysulfone polymer solutions containing cerium-activated yttrium si licate particles (GAYS) as a fluor. Membranes were formed by three dif ferent solidification processes: precipitation of the polymer-rich pha se after liquid-liquid phase separation, vitrification via solvent eva poration, or rapid polymer collapse due to fast exchange between solve nt in the solution and nonsolvent in the coagulation bath. The results indicate that when the coagulation process includes the liquid-liquid phase separation due to nucleation of the polymer-lean phase, the ino rganic fluor particles are expressed out of the polymer-rich phase and separated from the polymer matrix. On the contrary, solidification by the vitrification of the polymer solution through solvent evaporation results in the inorganic fluors being surrounded by the polymer matri x, much like the dispersed state in the solution. In contrast, rapid c ollapse of the polymer also induces entrapment of the fluor in the pol ymer structure. However, fluor impregnation in the polymer matrix is d istinguished from that in the vitrified membrane in that the impregnat ion is due to localized impingement of the fluor on the polymer struct ure rather than envelopment by polymer molecules. (C) 1998 Elsevier Sc ience B.V.