We show that conductivity measurements on sandwiches of a polymer between normal-metal and superconducting-metal
electrodes can be interpreted in terms of intrinsic superconductivity due to injection of charge into the polymer.
We have observed that films of a polyimide precursor of poly[4,4'-bis(4"-N-phenoxy)diphenyl-sulfone] amid acid of 1,3-bis(3',4-dicarboxyphenoxy) benzene which is called type (1) polymer- or co-poly[4,4'-bis(4"-N-phenoxy)diphenyl-sulfone-α,ω-bis(η-amino propyl)oligodimethylsiloxane]imide of 1,3-bis(3',4-dicarboxyphenoxy)benzene type (2) polymer, placed between two metallic electrodes become highly conducting in a relatively small electric field (E<1 V/cm). If the metallic electrodes (Sn, Nb) in sandwich structures were in the superconducting state an effective resistance of zero was recorded. A typical current-voltage characteristic of an S-P-S structure looks like a Josephson type. We hve experimentally shown that for a S-P-S structure, a point contact between the superconductor and the polymer film plays the role of a weak link.