Phosphorous waterborne polyurethanes/single-walled carbon nanotube composites as flame retardant building materials and their application in architectural design

Abstract

Development of building materials with high flame retardancy and electromagnetic interference (EMI) shielding is an urgent issue. Given the superior advantages of single-walled carbon nanotubes (SWCNTs) including excellent thermal/electric conductivity and low percolation threshold as fillers, novel phosphorous/SWCNTs/waterborne polyurethanes (P/SWCNTs/WPUs) were fabricated by an in situ polymerization, in which SWCNTs with small bundle (8.32 nm of average diameter) were prepared via a floating catalyst chemical vapor deposition. Multiple characterization results including composite morphology, increasing ratio of emerging covalently bonding of nitrogen/phosphorous revealed the successful phosphorous-containing composite of P in matrix. Composite with 15 wt% SWCNTs exhibited excellent flame retardant including 4.6 cm of damage length and 34.1% of limiting oxygen index without obvious destroy of original morphology. Superior electrical conductivity (4.52 S cm⁻¹) and EMI shielding (21.8 dB) were exhibited. More obvious rising trend of reflection values (4.6–19.3 dB) than that of absorption values (4.9–9.6 dB) indicated that the improvement of reflection derived from the conductivity enhancement with higher SWCNT content. Moreover, an excellent EMI shielding durability with 1.8% of reduce was achieved after 1000 times of bending. The applications of P/SWCNTs/WPUs in the building design for walls were discussed. This study provided a new insight in the usage of SWCNTs in flame retardant and EMI polymers.