Plant bio-inspired laminar cellulose-based foam with flame retardant, thermal insulation and excellent mechanical properties

Plastic foam has received extensive attention as a potential thermal management material for energy-efficient buildings. However, manufacturing an environmental cellulose-based foam material with excellent mechanical properties, flame retardancy, and low thermal conductivity remains a great challenge. In the present work, we developed a novel and facile method to fabricate a cellulose-based foam from pulp fibers, cellulose nanofibrils (CNFs), and borates, in which borates acting as both flame retardants and crosslinkers build a strong porous and laminar structure with fibers. The resulting foam exhibits ultralow density (12.1 mg cm(-3)), high flame retardancy, outstanding thermal insulation ability (with a thermal conductivity of 48.6 mW mK(-1)), and excellent mechanical properties (with a specific modulus of 15.3 MPa cm(3) g(-1) in the X direction). This work paves a new way for the synthesis of flame retardant insulation foam materials with great potential for practical applications in energy-efficient buildings.