The morphology studies of this bio-inspired coating technique (LbL assembly) were conducted by the SEM (Scanning Electron Microscopy. Pristine PUF and PUF coated with 5 BLs (bilayers) of flame-retardants via LbL assembly were examined (see figure below). The porous structure and internal skeleton of the PUFs were clearly revealed in the figure (a) to (e). Pristine PUF in (a) (low magnification) & (b) (high magnification) showed that the surfaces of uncoated PUF are neat and smooth. Moreover, figure (c). (d) and (e) (5 BL coated PUF) illustrates that the bio-inspired coated techniques maintained the inner wall structure of the PUF without any deformation after the coating procedure. Higher magnification images ((d) and (e)) revealed that with the coating on the PUF, the internal surfaces of the skeleton become rough. However, no-gaps or cracks were found in the images indicates that coating flame-retardants on the PUF using bio-inspired technique (LbL) assembly render the substrate a uniform and compact coating without any flaws.
