Carbon aerogels from furan-based polybenzoxazine precursors

Abstract

Carbon aerogels have found applications in energy storage, adsorbents, and as thermal insulators due to their high electrical conductivity, chemical resistance, and the ability to withstand extreme temperatures before degradation. Furan-based polybenzoxazines have been reported to have high char yields, while exhibiting excellent polymer properties including near zero volume shrinkage during cure and high glass transition temperature making them interesting candidates as the precursor network to carbon aerogels. In this study, carbon aerogels were fabricated from a 4-hydroxybenzyl alcohol furan-based benzoxazine (Bz-FA-H) and a bisphenol A furan-based benzoxazine (Bz-FA-BPA). The impact of monomer concentration on physical properties was assessed providing a framework for the fabrication of carbon aerogels from these precursors. A post cure thermal aging step was found to increase char yield of the precursor network and also increase surface area of the carbon aerogels fabricated. Furthermore, evolved gas analysis was utilized to understand the impact that the physical aerogel structure had on the carbonization reaction both before and after this post cure step. Finally, the carbon aerogels were assessed for their mechanical properties and thermal protection capabilities. The carbon aerogel from Poly(Bz-FA-H) precursor had increased surface area (>500 m² g⁻¹) and thermal protection capabilities, while the Poly(Bz-FA-BPA) precursor had increased Young's modulus (221 MPa) developing an understanding that the material properties can be tailored through chemistry.