Figure 1: A hierarchical structure of wood from macro to nano (a), reprinted from Isogai et al. [10]. The molecular structure of cellulose showing the β-D-glucopyranose molecule connected through β-1,4-glycosidic bonds. The inter- and intra-chain hydrogen bonds are shown by red and blue solid lines, respectively (b) Adopted from Thiruvengadam and Vitta [11].