SELF-SUPPORTED PEDT PVC CONDUCTING MEMBRANES FOR 4-PI-BETA SOURCES PREPARATION/

Gold-coated membranes stretched on stainless steel rings are generally used for the preparation of high quality 4 pi beta counting sources. We propose an alternative method for the preparation of such sources b y the use of a low-Z composite conducting polymer; [poly(3,4-ethylene dioxythiophene)/poly(vinylchloride)] (PEDT/PVC). A solution containing an EDT monomer (3,4-ethylene dioxythiophene), an oxidizing agent [Fe( CH3-phi-SO3)(3)], PVC and tetrahydrofuran as solvent is spin-coated on to a glass substrate. After coating, the membrane is dried, removed an d transferred to the surface of a water bath before being deposited on a stainless steel ring. This procedure takes little time in contrast to other methods. PEDT/PVC has a lower electrical conductivity than PE DT alone but the PVC provides the required tensile strength for the me mbrane self-support. Performances of usually used preparation techniqu es are compared. Parameters like beta detection efficiency for Co-60, peak to valley ratio for Cd-109 and aging are also discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.