Novel Electroactive Polymers as Environmentally Compliant Coatings for Corrosion Control

The objectives of this SERDP program WP 1148 have been completed successfully. The synthesis, scale-up and characterization of new monomers based on a bis-amino derivative of poly-p-phenylene vinylene PPV called poly2,5-bisN-methyl-N-hexylaminophenylene vinylene, BAM-PPV and oligomers of polyaniline have been completed. These polymers have been thoroughly characterized using advanced spectroscopic and analytical methods. The details regarding the EAP synthesis has been published in the literature for duplication including potential industrial use. BAM-PPV pretreatment coating on Al 2024-T3 processed from different solvents passed 336 hours neutral salt fog exposure. This test is required for new pretreatment coatings on aluminum alloys. Additional pretreatments were also studied including trivalent chromium pretreatment TCP. BAM-PPV coatings in several cases exceeded the 336 hour requirement. BAM-PPV has also been incorporated into full military coating systems that include non-chrome primers and topcoats. These coatings have been tested against known controls such as chromium primers and TCP pretreatment with non-chrome primer and topcoat. BAM-PPV performed as well as the TCP pretreatment with non-chrome primer and topcoat. However, in both cases, each coating did not pass the 2000 hours neutral salt fog exposure test. When BAM-PPV was used with chromium primer and topcoat, this coating system lasted over 4000 hours in a neutral salt fog chamber. Studies by ENM, SVET and XPS showed evidence that BAM-PPV provides more than simply barrier protection to corrosive environments and may passivate the metal surface.