Matrix Doping of ZnO and In₂O₃ in Para-Aramid via Vapor Phase Infiltration for Enhanced Electronic Properties

In this study, we introduce and alter electrical conduction into para-aramid (aka Kevlar) fibers by utilizing vapor phase infiltration (VPI) to introduce the metal oxide semiconductors ZnO and In 2 O 3, thereby creating a functional hybrid material. VPI leads to an inverted, matrix doping of the introduced semiconductor by the surrounding polymer. The initial insulating para-aramid contains benzenoid rings in its backbone. During infiltration, some of these benzenoid rings transform into quinoid rings, causing a change in the charge density within the polymer chain. This alteration directly affects the bands, photoluminescence, and conductivity of the resulting hybrid fibers. Our findings demonstrate a substantial reduction in electrical resistance of the hybridized para-aramid, surpassing the pristine state by approximately 6 orders of magnitude. Remarkably, exposure to visible light notably enhances the photoconductivity of the ZnO-infiltrated para-aramid, reducing the electrical resistance by 7 orders of magnitude compared to pristine para-aramid. Additionally, we introduce In 2 O 3 as an alternative inorganic compound for VPI, expanding the process’s applicability. The In 2 O 3 -infiltrated para-aramid exhibits even lower electrical resistance, achieving an impressive reduction by 12 orders of magnitude compared to the pristine state, highlighting the advantages of VPI with In 2 O 3 .