Matrix Doping of ZnO and In<sub>2</sub>O<sub>3</sub> in Para-Aramid via Vapor Phase Infiltration for Enhanced Electronic Properties
Natalia Chamorro, Itxasne Azpitarte, Marta Autore, Hayrensa Ablat, Iva Šarić, Ibán Amenabar, Christopher Tollan, P. Vavassori, Rainer Hillenbrand, Simon D. Elliott, Mato Knez
Abstract
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 .