Bioinspired sustainable cellulose-based nanocomposites with remarkable flame-retardant performance

Abstract

Cellulose nanofibers (CNF) have a wide range of applications in daily life, yet their inherent flammability poses potential fire hazards and risks. Enhancing the flame resistance of CNF is a challenging task. Inspired by the layered “brick-and-mortar” architecture of nacre, a novel flame-retardant material was prepared in this work. The process involved modification of cellulose-rich pulp paper with a solution containing phytic acid and urea, creating phytic acid-modified cellulose nanofibers (PA-CNF) through a mechanical shearing technique. Subsequently, PA-CNF and graphene oxide (GO) were utilized as assembly units, with calcium chloride (CaCl₂) serving as a crosslinking agent. A nacre-mimetic film was fabricated via layer-by-layer coating and hot pressing, with GO as “bricks” and PA-CNF as the “mortar”. The flame retardancy of PA-CNF was significantly enhanced following phytic acid modification, and the resultant nacre-mimetic material demonstrated remarkable flame retardancy and mechanical properties, achieving a state of complete non-flammability. The nacre-mimetic structure provides superior insulation against heat, oxygen, and smoke, thereby enhancing safety measures. Moreover, the mixed solution of PA-CNF and GO has potential applications as flame retardant and thermal insulation coatings.