Although the production of electro-conductive aramid fibers is efficient, the method needs to be modified before it can be applied to aramid films. Whereas impregnation of an aramid film with a metal complex using supercritical CO 2 is achievable, the relatively low adhesion strength of the metal layer applied using electroless copper plating is problematic. To solve this problem, thermal treatment was conducted before, after, or both before and after electroless plating. The rationale for using thermal treatment to improve the adhesiveness of the plated layer was based on the findings that (1) an aramid film contains a significant amount of water (about 3.5 % w.o.f.), which might have a negative impact on adhesion; and (2) because an impregnated metal complex liberates metal catalyst by thermal decomposition during impregnation, a supplementary thermal action might liberate more catalyst and thereby improve adhesion. We found that thermal treatment improved adhesion of the metal layer to the aramid film. Moreover, we discovered that with respect to electroless copper plating, a short time-lag was crucial to obtaining a thin and homogeneous metal layer with strong adhesion. In addition, we demonstrate the affinity of an aramid film for Pd(acac) 2 .

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.

For over 50 years, plastic materials have been replacing metals in many different fields (automobiles, housing, safety and computers). Indeed, polymers are more versatile and can thus be modeled to exactly fit their new specific usages such as intelligent fibers or nano fibers. However, until recently, scientists faced the problem of the non-conductivity of polymers. Hence, they developed various metallization processes 1-3 to create smaller and lighter electrical devices. With the realization that industrial waste leads to environmental problems 4, new techniques have been developed to comply with new ecological legislation 5, 6. Supercritical carbon dioxide (sc-CO2) is a widely used medium because of its intrinsic properties. Sc-CO2 is completely recyclable, does not generate waste water and is an efficient replacement for many organic solvents 7. Moreover, it has high diffusivity, low viscosity and high thermal conductivity, and is available at low cost. Sc-CO2 addresses safety considerations as well, since it is nonflammable and non-reactive under most conditions. Due to those properties, sc-CO2 is a valuable medium in the fields of extraction 8, dyeing 9 and impregnation 10. In the case of polymer impregnation, sc-CO2 plasticizes the matrix and swells it, thereby providing the room necessary to for the impregnation of solutes with relatively large molecular weights, such as organometallic