Influence of hierarchical porous structures on the mechanical properties of cellulose aerogels

Aerogels of cellulose exhibit remarkable mechanical properties as a function of density. Modifying the pore volume in classical cellulose aerogels using sacrificial template methods provide scaffold like microstructure. In the present study, we have developed aerogels of cellulose scaffolds having almost same density values but differ in microstructure and analysed the influence on the mechanical properties of bulk materials. This study can give an insight into the materials design for advanced engineering materials. Employing four surfactants having difference in hydrophilic-lipophilic balance (HLB), namely polyoxyethylene tert-octylphenyl ether (PT), polyoxyethylene (20) oleyl ether (PO), polyoxyethylene (40) nonylphenyl ether (PN) and polyoxyethylene (100) stearyl ether (PS), the cellulose scaffolds with hierarchical porous structures were developed. The mechanical properties of cellulose scaffolds were compared with classical pure cellulose aerogels. The results indicate that the solid fraction of cellulose nanofibers per unit volume of cell walls of scaffolds plays an important role in determining the elastic properties and strength. As the nanofibrils support the cell walls of scaffolds, Young’s modulus can be improved if the concentration of cellulose nanofibers is high at the cell walls or cell wall thickness is larger. The scaffold materials of this kind could be used as supporting materials with desired properties for filter, catalysis and biomedicine.