hydrophylic polyacids , such as macromolecules of polyitaconic acid and polyacrylic acid , where such macromolecules have molecular weights & gt ; 50 , 000 as primers between a polymeric top coating , such as polyurethane , and an oxidized aluminum or aluminum alloy . a near monolayer of primer is used in polymeric adhesive / oxidized aluminum adhered joint systems in 0 . 05 % primer concentration to give superior results in standard peel tests .