Application of Dithiol Compounds in Supercritical Carbon Dioxide to Improve the Adhesive Properties of Copper-Plated p-Aramid Fibers

Supercritical carbon dioxide (scCO2) has been used to impregnate the organometallic complexes in a synthetic polymer prior to electroless copper plating. However, this method has not been applied to highly crystalline and highly oriented polymers, such as p-aramid fibers. In this study, triazine dithiols were used to create a network that consisted of Kevlar® fibers, the organometallic complex palladium (II) hexafluoroacetylacetonate [Pd(hfa)2], and a metal layer. This network improved the adhesion of a copper layer that was added by electroless plating. Three triazine thiols were used, two of which were soluble in scCO2 and one of which was soluble in water. Pretreatment of the Kevlar® fibers comprised two steps : 1) impregnation with a thiol compound, using sc-CO2 or the thiol-water solution ; and 2) impregnation with an organometallic metal complex using sc-CO2. Electroless plating was performed to coat the treated Kevlar® fibers with a layer of copper. By changing the experimental conditions (i.e., pressure, temperature, thiol concentration, and order of impregnation), we found that the triazine thiol improved the electrical resistivity and adhesion of the copper layer.