Transparent, electrically conductive composite films were obtained by vapor-phase polymerization of pyrrole into a poly(viny1 chloride) (PVC) matrix containing FeC13. The effects of water and of organic solvents on the polymerization were investigated. It was found that the conductance of the films increases in the presence of both water vapor and of good solvents or swelling agents for PVC. The conductivity of the films rises with reaction time and so does the rate of increase with higher FeCI3 concentration. The production of HCl was monitored by two methods, the precipitation of AgCl in an aqueous solution of silver nitrate and the increase in conductance of an aliquot of distilled water which had been placed into the reaction ch.smber. On the basis of our experimental results, we propose a reaction mechanism that explains the observed increase of conductance with time. A universal kinetic formula has been *Permanent address:

The results of this study may explain the higher incidence of hypoglycemic episodes observed in patients with type 2 diabetes when taking ACE inhibitors together with sulfonylureas or insulin. ACE inhibitors may cause a temporary increase of the insulin sensitivity, which leads to an increased risk of hypoglycemia under these conditions.

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