Composition for the controlled release of inhibitors for corrosion, biofouling, and scaling

Abstract

A polymer composite structure, wherein the composition releases an anionic dopant upon application of an electrochemical potential, such as when in contact with a metallic substrate in a corrosive environment. The composite actively inhibits corrosion at the point of contact of the composite with a metal substrate by release of “active” or “smart” corrosion inhibitors which migrate to the corrosion area. Composites having anionic dopants having biocidal or scale-inhibiting properties may be used to inhibit biofouling and scaling wherein the dopants are released upon application of a electrochemical potential.

1 . A composite structure that releases an anionic dopant upon application of an electrochemical potential, said composite comprising: 
 a fibrous material impregnated with a resin matrix, wherein the resin matrix comprises a conducting polymer and an anionic dopant associated with said polymer, wherein said dopant is dissociable from said polymer upon contact with a metal substrate under oxidating conditions.    
     
     
         2 . The composite structure of  claim 1 , wherein said dopant includes a compound selected from the group consisting of monothiols and dithiols.  
     
     
         3 . The composite structure of  claim 1 , wherein said dopant includes the anion of an organic acid.  
     
     
         4 . The composite structure of  claim 1 , wherein said dopant selectively disassociates from said conducting polymer when said conducting polymer becomes more basic than when protonated by said dopant acid or is reduced.  
     
     
         5 . The composite structure of  claim 1 , wherein said dopant becomes associated with said conducting polymer when said dopant acid protonates said conducting polymer.  
     
     
         6 . The composite structure of  claim 1 , wherein the conducting polymer includes polyaniline.  
     
     
         7 . The composite structure of  claim 1 , wherein the fibrous material is selected from the group consisting of glass, metal, minerals, conductive or nonconductive graphite or carbon, nylon, polyaramids.  
     
     
         8 . The composite structure of  claim 1 , wherein the dopant has biocidal properties or is an effective scaling inhibitor.  
     
     
         9 . A corrosion resistant metal article, comprising: 
 a metal substrate galvanically connected to a composite structure, wherein the composite structure comprises    a fibrous material impregnated with a resin matrix, wherein the resin matrix comprises a conducting polymer and an anionic dopant associated with said polymer, wherein said dopant is dissociable from said polymer upon oxidation of the metallic substrate.    
     
     
         10 . The metal article of  claim 9 , wherein said dopant includes a compound selected from the group consisting of monothiols and dithiols.  
     
     
         11 . The metal article of  claim 9 , wherein said dopant includes the anion of an organic acid.  
     
     
         12 . The metal article of  claim 9 , wherein said dopant selectively disassociates from said conducting polymer when said conducting polymer becomes more basic than when acidified by said dopant or is reduced.  
     
     
         13 . The metal article of  claim 9 , wherein said dopant becomes associated with said conducting polymer when said dopant protonates said conducting polymer.  
     
     
         14 . The metal article of  claim 9 , wherein the conducting polymer includes polyaniline.  
     
     
         15 . The metal article of  claim 9 , wherein the fibrous material is selected from the group consisting of glass, metal, minerals, conductive or nonconductive graphite or carbon, nylon, polyaramids.  
     
     
         16 . The metal article of  claim 9 , wherein the metallic substrate is a component of a cooling tower.  
     
     
         17 . The metal article of  claim 9 , wherein the metallic substrate is a component of a radiator cap.  
     
     
         18 . The metal article of  claim 9 , wherein the metallic substrate is a component of an aircraft.  
     
     
         19 . The metal article of  claim 9 , wherein the metallic substrate is a component of a watercraft.  
     
     
         20 . The metal article of  claim 9 , wherein the metallic substrate is a component of a pipeline.  
     
     
         21 . A method for inhibiting corrosion of a metallic substrate, comprising: 
 galvanically contacting the metallic substrate with a composite structure comprising    a fibrous material impregnated with a resin matrix, wherein the resin matrix comprises a conducting polymer and an anionic dopant associated with said polymer, wherein said dopant is dissociable from said polymer upon contact with a metal substrate under oxidating conditions.    
     
     
         22 . The method of  claim 21 , wherein said inhibiting anion is formed from an acid that is able to become associated with said polymer when said acid protonates said polymer.  
     
     
         23 . The method of  claim 22 , wherein said inhibiting anion is disassociable from said polymer when said polymer is made more basic than when it is protonated.  
     
     
         24 . The method of  claim 22 , wherein said inhibiting anion is disassociable from said polymer when said polymer is reduced.  
     
     
         25 . The method of  claim 21 , wherein said inhibiting anion is derived from a molecule selected from the group consisting of acidic thiols and non-acidic thiols.  
     
     
         26 . The method of  claim 21 , wherein said inhibiting anion is formed from dissociation of an organic acid.  
     
     
         27 . The method of  claim 21 , wherein the conducting polymer is associated with the dopant by: 
 doping a cationic polymer with a first anion;    converting the cationic film into an oxidized form; and,    exchanging the first anion with the inhibiting anion from a solution of a salt of the inhibiting anion.    
     
     
         28 . The method of  claim 20 , wherein the dopant has biocidal properties or is an effective scaling inhibitor.  
     
     
         29 . The method of  claim 21 , wherein the step of doping the cationic material comprises: 
 protonating the film with an acid including an acid anion; and,    exchanging the acid anion with the inhibiting anion.