# A Top-Down Approach to the Fabrication of Flame-Retardant Wood Aerogel with In Situ-Synthesized Borax and Zinc Borate

## TL;DR

This paper describes a method to create flame-retardant wood aerogels using a top-down approach with in situ-synthesized flame-retardant compounds.

## Contribution

The novel contribution is the in situ synthesis of borax and zinc borate during the fabrication of flame-retardant wood aerogels.

## Key findings

- The NaOH treatment created a layered wood structure with uniformly distributed flame-retardant particles.
- The flame-retardant aerogel achieved a UL-94 V-0 rating and an LOI exceeding 90%.
- The PHRR and THR were significantly reduced compared to control samples.

## Abstract

In this study, a top-down approach was employed for the fabrication of flame-retardant wood aerogels. The process involved the removal of lignin and the removal of hemicellulose utilizing NaOH concomitantly with the incorporation of ZnO and urea. Subsequently, an in situ reaction with boric acid was conducted to prepare flame-retardant wood aerogels. The morphology, chemical composition, thermal stability, and flame retardancy of the samples were studied. The results show that the NaOH treatment transformed the wood into a layered structure, and flame-retardant particles were uniformly distributed on the surface of the aerogel. The peak heat release rate (PHRR) and total heat release (THR) of the flame-retardant aerogel were significantly reduced compared with the control samples. Meanwhile, its vertical burning test (UL-94) rating reached the V-0 level, and the Limiting Oxygen Index (LOI) could exceed 90%. The flame-retardant wood aerogel exhibited excellent flame retardancy and self-extinguishing properties.