Electromagnetic Interference Shielding Performance of Poly(styrene-<i>co</i>-butyl acrylate)/Carbon Nanotube Nanocomposites Fabricated by Latex Technology

Abstract

With the increase in electronic devices emitting radio and electromagnetic waves, it has become increasingly crucial to improve electromagnetic interference (EMI) shielding properties. In this study, to provide efficient shielding performance, copolymer/carbon nanotube (CNT) nanocomposites were fabricated using latex technology with colloidal monodisperse copolymer particles and surface-modified nanofillers. The copolymer was synthesized using styrene and butyl acrylate to enhance impact resistance, and thus, colloidal resin having a low glass transition temperature was obtained. The nanofiller, i.e., CNT, was surface-modified by wrapping it with two types of hydrophilic polymers, poly(styrenesulfonate) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), to improve the dispersibility of CNT in aqueous colloidal suspensions. After investigating the morphological, thermal, and rheological properties of the matrix resin, the EMI shielding effectiveness (SE) of nanocomposite films was analyzed by varying the nanofiller type and content and the number of film layers. The degree of reflection and absorption shielding effects of the nanocomposites were compared at the frequency range of 50 MHz–1.5 GHz using the measured S-parameter. Wrapping hydrophilic and electrically conductive polymers on CNTs improved their dispersity in the aqueous suspension, thereby enhancing the SE. With the same thickness, the performance was improved as the number of stacked layers increased. In particular, the absorption shielding of the nanocomposites was more dominant than the reflection shielding. These copolymer/surface-modified CNT nanocomposites can be employed in various applications that require EMI shielding performance