Microwave absorption and infrared emissivity of helical polyacetylene@multiwalled carbon nanotubes composites

Abstract

Hybrids of polyacetylene (PA) with multiwalled carbon nanotubes (MWNTs) were fabricated by wrapping PA derivatives containing stigmasterol and pivalic acid moieties onto MWNTs walls. The PA derivatives with moderate molecular weights (Mn ~ 24409) were proved to adopt a single-handed helical structure stabilized by asymmetric hydrogen bonding force and stereo-hindrance effect. Convincing experimental results show that PA had been wrapped evenly on the surface of MWNTs without damaging their internal structures. Moreover, the helical structure of PA became more compact and ordered after wrapping around MWNTs. The incorporation of stigmasterol moieties could contribute to enhancing the microwave absorbing properties and decreasing infrared emissivities. PA@MWNTs showed a minimum reflection loss value of −20.65 dB at 9.7 GHz and the bandwidth of reflection loss less than −10 dB (90% absorption) was 3.2 GHz. Meanwhile, PA@MWNTs composites had a much lower infrared emissivity value (e = 0.503) than raw MWNTs. The efficient microwave absorption and low infrared emissivity might result from the synergistic effect of the extraordinary helical structure of PA and π-electronic interactions between the organic substituents and inorganic MWNTs walls, which provides a promising method to prepare materials with low infrared emissivities and excellent microwave absorption properties.