DNA-based nanocomposite biocoatings for fire-retarding polyurethane foam

Layer-by-layer (LbL)-assembled multilayer thin films of deoxyribonucleic acid (DNA), chitosan (CHI) and montmorillonite (MMT) were studied in an effort to produce fully renewable, bio-based, fire-retardant coatings for flexible polyurethane foam. The polyurethane foam (PUF) biocoatings constructed of ten bilayers (BLs) of CHI/DNA+MMT (16.2 % mass), ten trilayers of CHI/MMT/DNA (8.1 % mass) and five quadlayers of CHI/DNA/CHI/MMT (4.9 % mass) all resulted in a significant reduction in critical flammability metrics, peak heat release rate (pHRR) and average HRR (aHRR). The mix BL, CHI/DNA+MMT, is the best formulation as it resulted in the greatest flammability reduction (51% pHRR and 81% aHRR) with the fastest biocoating growth and the least amount of preparation and waste. This DNA-and MMT-based biocoating is the greatest flammability reduction of PUF reported to date using the LbL process. Constructed of bio-based and non-toxic materials combined with the fast-growing BL approach, which has minimal waste, this is presumably the most environmental and bio-friendly fire-retardant LbL coating on flexible polyurethane foam reported. This article contains supporting information that will be made available online once the issue is published.