Method of making a polymer film having a conductivity gradient along its thickness and polymer film so made

Abstract

A polymer film having a conductivity gradient across its thickness is maderom a mixed solution of an insulating polymer, A and a polymer, B that can be made conducting by doping or protonation by a method including the steps of: (A) mixing the solution of the insulating polymer, A and the polymer, B that can be made conducting by doping or protonation, (B) casting the mixed solution together as a solid composite film, and (C) exposing the film to a treating agent that can dope or protonate polymer B and make polymer B conductive and create a conductivity gradient across the thickness of the polymer films.

What is claimed is: 
     
       1. Method of making a polymer film that has a conductivity gradient across its thickness from a mixed solution of an insulating polymer, A, and a polymer, B that can be made conducting by doping or protonation, said method including the steps of (A) mixing the solution of the insulating polymer A, and the polymer, B that can be made conducting by doping or protonation,   (B) casting the mixed solution together as a solid composite film, and   (C) exposing the film to a treating agent that can dope or protonate polymer B and make polymer B conductive and create a conductivity gradient across the thickness of the polymer film.   
     
     
       2. Method according to claim 1 wherein the treating agent is a dopant. 
     
     
       3. Method according to claim 1 wherein the treating agent is a protonator. 
     
     
       4. Method according to claim 1 wherein the treating agent is allowed to diffuse into the solid composite film as a function of time causing the polymer B molecules near the surface region to be converted to the conducting form. 
     
     
       5. Method according to claim 3 wherein the treating agent protonator is HCl gas and polymer B is "POMA" (poly-o-methoxyaniline).